Nightside: Cosmic Beings and General Cosmology

Table of Contents
-The Outside and the Outsiders
-Limbo and the Overworld
-Heaven, Hell, Angels and Demons
-Transient Beings

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The Outside and the Outsiders

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A brief explanation regarding the nature of Outsiders:

“Do you know the kind of Things from Outside we’re talking about?” I said carefully. “They exist in dimensions far from ours, far from reality, as we understand it. They’re not even life, as we understand it. They hate life, and destroy it wherever they find it. They want to destroy the Light, until there’s nothing left but the Darkness they hide in.”

“You’re saying they’re evil?” he said politely.

“They’re so different from us they’re beyond simple labels like Good and Evil. Those are human beliefs, human concepts. They’re bigger than that, beyond that, monstrous beyond anything we can imagine because our concept of evil isn’t big enough to encompass the things they do. We call them Outsiders because they’re outside anything we can understand or accept: outside morality, or sanity, maybe even Life or Death.” -A Hard Day's Knight

Another statement regarding the Outside:

“The destruction of hundreds of dimensional gateways might be enough to fracture reality and blast open other doors. The kind that lead to places we like to think of as Outside our reality. The kind of door we’ve done everything but barricade and nail shut from this side. You know the kind of dimensions I’m talking about, John. Where Things from Outside have been waiting for millennia, just for a chance to force their way in and destroy every living thing in creation. Do I really need to say the Names?” -A Hard Day's Knight

Outsiders exist outside of time:

And once I was locked on to that terrible place, the angel tore me loose from the Present, and sent me rocketing forward through Time. The world speeded up around me, Time flashing by impossibly fast. Days became months became years, piling up behind me. I saw the Nightside fall, its great buildings crashing down, crumbling like sand castles in the path of an oncoming tide. I saw the great oversized moon in the night sky explode, its pieces raining down like fiery meteors. And I saw the stars start to go out, one by one by one.

There were Voices all around me, growling and muttering and howling, outside of Time. Strange Presences, all speaking at once in no human tongue, yet still I could understand the gist of it. Slowly they became aware of me, then the Voices began to cajole, to warn, and to threaten. I think they were frightened of me. I refused to listen, making myself concentrate only on my destination, until finally Time slammed to a halt again, and I was spilled out into the dark future I’d visited before. The dead end of the Nightside, and maybe all of history.

And all of it my fault. -Sharper Than a Serpent's Tooth

This time it didn’t feel like falling through Time but more like being flung from a catapult. A rainbow exploded around us, punctuated by exploding galaxies and the cries of stars being born, while from all around came the screaming and howling of Things from Outside, crying Let us in! Let us in! in languages older than the worlds. Suzie Shooter and I finally dropped out of the chronoflow and back into Time, slamming back into the world like a bullet from a gun. -Paths Not Taken

Both higher and lower-dimensional beings are implied/stated to come from Outside:

And that was when I noticed something ... odd. Despite all the tension and chaos, and the threat of imminent violence on all sides, I was humming the tune of an old song from the seventies. It was "Bridget the Midget the Queen of the Blues"; one of those comedy novelty singles by Ray Stevens. Hadn't thought of it in years. Even stranger, most of the people nearest me were humming the same tune. Some had even broken off bidding to sing along, though their expressions suggested they didn't know why. I got chills up my back, as I realised the song was spreading through the crowd. In the Nightside, coincidence and compulsion often meant something. And what it usually indicated was interference from Outside.

And then even Grave stopped taking bids and rubbed hard at her forehead, as though bothered by some intrusive thought. Sandra Chance and the Painted Ghoul were both on their feet, looking confusedly about them. A growing murmur of unease ran through the crowd. The song's moment had passed, but we could all feel something—a growing sense of pressure from a direction none of us could name. More people rose to their feet, looking round wildly. No-one new had come into the Hall, but we all knew we weren't alone any more.

"Something's coming," said Sandra Chance. "Something bad."

A few people protested at the interruption of the bidding, but were quickly shouted down. Pretty much everyone was on their feet now, looking around for threats but seeing nothing. Various weapons appeared in nervous hands. The teddy bears huddled together, hints of claws appearing on their padded paws. The Hall grew silent and tense. There was a growing pressure on the air, like a gathering storm, like the moment before lightning strikes. And suddenly, all around the Great Auction Hall, wards and protections that had stood for centuries broke and blew apart in coruscations of vivid energies, shattered by a growing presence they were never meant to contain or keep out—a living presence, vast and inhuman, seeping into our reality like poison into a clear spring.

I knew what it was, what it had to be. I recognised the signs. A psychenaut; a traveller from some higher or lower dimension. An intruder that could not be stopped or turned aside because it was either too real or not real enough to be affected by human powers. I'd had some experience with psychenauts, back when I apprenticed with old Carnacki, the Ghost Finder. It didn't seem fair that I should have to face something so awful twice in one lifetime. I would have run, but I knew I'd never make it. -Hex and the City

Sandra Chance's aboriginal pointing bone forces several psychenaut (read: Outsider) animating forces "out of the material world", but they're able to come back as long as the psychenaut itself is still present within the material world:

Sandra Chance's magics were mostly useless, being concerned primarily with the dead, not elementals, but she was still fighting back. She stood proudly in a shimmering circle of protection, magnificently angry, forcing back the psychenaut intrusions by sheer force of will. She had an aboriginal pointing bone, and in whichever direction she trained it the animating forces were thrust out of the material world. But only for a while. They always came back. -Hex and the City

A higher-dimensional psychenaut appears, and is stated to be too large and "too real" for normal Space-Time. Its mere presence in the material world causes an entire host of horrific things to happen to everything around it:

And Sandra Chance said, in a heartbreakingly matter-of-fact voice, "Something else is coming."

It was another psychenaut. A traveller from a higher dimension this time. We could all feel it coming, could feel Something unbearably vast descending into our reality. Something so impossibly big it had to compress itself to fit into our narrow Space/Time continuum. Everyone's first impulse, including mine, was to run, but the sheer force of the approaching Presence held us helpless where we were, like mice in the gaze of the serpent, or insects caught in the heat focussed through a magnifying glass. Something finally materialised in the Great Auction Hall with us, so huge and powerful it hurt our minds even to think about it, drawing everything towards it like a massive gravity well. It was too Real for our limited reality; so Real it sucked everything else into it.

The Presence settled heavily into our world, spreading out in directions we couldn't even name; something Huge and Vast downloaded from a higher dimension. Its thoughts smashed into everyone's minds, as harsh and merciless as a spotlight, searching for the single significant thing that had brought it to this petty, limited place. It didn't take a genius to realise it must be looking for the chaos butterfly. The only truly unique thing at the auction. The psychenaut couldn't seem to locate it exactly for the moment, presumably because of the stasis field holding the butterfly temporarily outside of Time and Space. And so the Presence sank deeper into people's minds, forcing their very selves away in its search for knowledge. All around me people were crying out in pain and shock and horror, shrieking Get it out of me! Even the major players were on their knees, sobbing and shaking. The only one left mostly unaffected in the Hall was me, and I didn't want to think why.

The psychenaut wasn't used to thinking in only three dimensions, but eventually it would locate the chaos butterfly, if only through a process of elimination. The pull of the gravity well was growing steadily stronger. Details of this world's reality were being stripped away and sucked in, absorbed by the Presence. Not because it chose to, but just because of what it was. The teddy bears lumbered towards it, drawn by some inexorable summons, only to fall one by one to the floor, reduced to just toy bears again. Terrible changes swept through those people closest to the Presence. Suddenly, some could only be seen from the back, no matter which way you looked at them. Faces lost their individuality, becoming blank and generic. Details of clothing disappeared as though smoothed away by an unseen hand, then lost their colour. People became black-and-white two-dimensional photographs, and finally just chalk drawings, until all they were was sucked into the gravity well. Stripped of everything that made them real.

I made myself ignore the screams and howls of the damned around me, thinking hard. The charm of Banishing wouldn't work on anything as powerful as this. Hell, nothing I had would even touch it. Powers as significant as this hardly ever gave a damn about lower dimensions like ours. -Hex and the City

Some Outsiders' attempt to superimpose their own reality upon the material one results in...this:

The whole room was full of flaring bright lights, sharp and incandescent, acutely painful to the human eye. Great clouds of flailing energies boiled this way and that, discharging violently against anything they touched. One whole wall had become wet and sticky, all the shades of red, pulsing like the insides of something alien. The ceiling seemed to be miles overhead, and the floor felt untrustworthy under my feet. Walking into the Ward was like pushing against a fierce wind, an almost solid intervention of some Outside will. I could feel Space itself stretched taut by some unimaginable influence. I stopped, despite myself, struggling to get my bearings. There were too many directions, too many dimensions inside Ward 12A now, too many ways to look, too many options to deal with. Another reality had been added to ours, superimposed on it, making the world heavier and more complex than it was ever supposed to be. The red wall was full of something like maggots, writhing and twisting. There were dark holes in the floor, dropping away forever. And rising over everything, a horrible feeling, a terrible conviction, that something was coming.

Far-away, from Outside or beyond our universe, I could hear something screaming, an endless howl of rage and hate. Drawing steadily, remorselessly closer.

And right there before me, hanging in mid air, was patient John Doe X 47, or what was left of him. His Humanity had been ripped away. His body was gone. He had been subtracted from the world and made into something else, and now he was a living tear in reality. A human gap, a human shape full of something that hurt my eyes to look at. A way in for whatever wanted in. I forced myself to look away, to check on what had happened to the other patients trapped in Ward 12A. I knew Julien would want to know. I could see all the beds, and the patients in them; but they all seemed far-away, distant, on the other side of the world. Looking across the Ward, across all its hideously stretched Space, was like looking across the universe. Trying to concentrate on the patients was like trying to look in a new direction, one I could sense but not make sense of. They’d been pushed aside by what was happening, forced out of the way to make room for what was pushing in. I was pretty sure the patients were still alive. But I couldn’t tell if they were still human any more. -The Bride Wore Black Leather

While the first book was written before the concept of the Outside had been properly established, The house-abomination on Blaiston Street which appears in said book is retroactively confirmed to have been an Outsider:

"The house is a predator," I said. "An alien thing, from some alien place, far outside our own space, where life has taken very different forms. It makes itself into what it needs to be, taking on the colour of its surroundings, hiding in plain sight, calling its prey to it with a voice that cannot be resisted. Its prey is the lost and the lonely, the unloved and the uncared for, the discarded flotsam and jetsam of the city that no-one ever misses when it washes up here, on Blaiston Street. The house calls, in a voice that no-one ever disbelieves, because it tells them just what they want to hear. It even sucked in a few supposedly important people, people perhaps a little too susceptible for their own good. Being important doesn't necessarily protect you from the secret despairs of the hidden heart." -Something from the Nightside

“You might remember a certain creature from Outside that pretended to be a house on Blaiston Street. It called people to it, then consumed them. After Taylor destroyed it, I had my people collect scrapings of the alien cell tissues and preserve them for analysis. As a result of what they discovered in their labs, I was eventually able to grow a new house, in a setting of my own choice. I had it lobotomized, of course, so it would only eat what I chose to feed it. Never know when you’ll need a secret weapon to use against your enemies.” -Sharper Than a Serpent's Tooth

Said being hid its heart inside of "a bare plain that stretched out to infinity in all directions", which is later confirmed to be another dimension of reality:

The nothing was replaced by something. An in-between place. I was standing on a bare plain that stretched out to infinity in all directions. It was a grey place, soft and hazy and indistinct. Not a real place, but real enough. A place to make a stand. Suzie and Cathy were there with me. Suzie was wearing silver armour, studded with vicious spikes. Cathy looked like she had in her old photo, only mad as hell now. I didn't look down to see how I appeared. It didn't matter. Not too far away there was another presence, too faint to be clearly seen, but I knew who it was. Who it had to be. We were all shining brightly now, luminous beings in a grey world. Together we formed a wide circle around a column of swirling darkness, shot with vivid blood-red traces, that towered endlessly up into the featureless sky. From it came the voice of the house, beating against us like hammer-blows, harsh and inhuman. -Something From the Nightside

"Where were we?" she said abruptly. "The grey place. What was that?"

"The house was only vulnerable through its heart," I said, urging her towards the place in the wall where the door had been. "So, the house hid its heart in another place. Another dimension of reality, if you like. It's an old magical trick. But I can find anything."

"Are you sure it's dead?" said Suzie. "All the way, not coming back in the last reel, dead? I mean, it's still here, and we're still trapped inside it."

"It's dead," I said. "And from the smell and general state of things, I'd say its body is already starting to decay. It never really belonged in our world. Only its augmented will allowed it to survive here. Suzie, make us a door."

She looked at me. "You might remember, my gun didn't work too well, last time."

"I think you'll find it will now." -Something from the Nightside

The Primal, a collection of blatantly higher-dimensional beings who appear in Nightingale's Lament, originate from the Outside:

We were almost half-way across the hall before we got our first glimpse of what was waiting for us. At the far end, in the darkest of the shadows, barely illuminated by the light of the swirling mists, were five huge figures. The corpsicles. Thawed from unimaginable cold, revived from the dead, reanimated by abhuman spirits from Outside, they didn't look human any more. The forces that possessed the vacant bodies were too strong, too furious, too other for merely human frames to contain. They had all grown and expanded, forced into unnatural shapes and configurations by the pressures within, and now they were changed and mutated in hideous ways. It hurt to look at them. Their outlines seethed and fluctuated, trying to contain more than three dimensions at once. Mere flesh and blood and bone should have broken down and fallen apart, but the five abominations were held together by the implacable will of the creatures possessing them. They needed these bodies, these vacant hosts. The corpsicles were their only means of access to the material world. I kept wanting to look away. The shapes the bodies were trying to take were just too complex, too intricate for simple human minds to deal with. -Nightingale's Lament

They state that they're purely conceptual beings who predate the material, and that they've existed for as long as Time itself:

One of the shapes leaned forward. It was twice as tall as a man, and almost as wide, its pale, sweating skin stretched painfully tight. A head craned forward on the end of a long, extended neck. Bloody tears fell constantly, to hiss and steam on the hall floor. Bone horns and antlers thrust out of the distorted face, and, when it spoke, its voice was like a choir of children whispering obscenities.

"We are The Primal. Purely conceptual beings, products of the earliest days of creation, before the glory of ideas was trapped and diminished in the narrow confines of matter. Kept out of the material worlds, to protect its fragile creatures of meat and mortality. Ever since Time was, we were. Waiting and watching at the Edge of things, searching eternally for a way in, to finally show our contempt and hatred for all the lesser creations, that dare to dream of being more than they are. We are The Primal. We were here first. And we will be here when all the meat that dares to think has been stamped back into the mud it came from." -Nightingale's Lament

Lilith can apparently travel between the material plane and the Outside through portals. When we see this, the portal leading to the Outside is described as leading "in a direction (John) couldn't identify, which had nothing to do with left and right, up and down":

But almost immediately another presence forced its way into the bar, slamming through Merlin’s defences. A door appeared in a wall where there had never been a door before, a ragged hole in the brickwork like a mouth or a wound, and stretched out beyond it was a narrow corridor, impossibly long. It led off in a direction I couldn’t identify, which had nothing to do with left and right, up and down, that my mind couldn’t deal with or accept, except simply as Outside. And down that awful corridor, slowly but inexorably, a single figure came walking. It was too far off in that unacceptable distance to see clearly, but I knew who it was, who it had to be. Lilith knew what we were up to, and she was coming to stop us. -Sharper Than a Serpent's Tooth

As seen with Kid Cthulhu, beings from Outside are capable of bonding with normal people as a means of growing through them, and do so in order to birth themselves a new form capable of existing within the material plane:

A new spotlight stabbed down from overhead, revealing Kid Cthulhu sitting on a huge reinforced chair, right in the centre of the open space. He looked like a man, but he wasn’t. Not any more. You could tell. You could see it, feel it. There was a taint in the man, all the way through. He had been touched, and changed, by something from Outside. Kid Cthulhu was a large man, he had to be, to contain everything that was in him now. He was naked, his skin stretched taut and swollen, as though pushed out by pressures from within. He was supposed to be about my age, but his face was so puffed out no trace of human character remained in it. He sat slumped in his oversized chair, like King Glutton on his throne. His bare skin gleamed dully in the mercilessly revealing spotlight, colourless as a fish’s belly, while his eyes were all black, like a shark’s.

They say he broke men’s bones with his bare hands. They say he ate the flesh of men, breaking open the bones to get at the marrow. They said there was something growing within him, or perhaps through him, from Outside. And right then, I believed every word they said. -The Unnatural Inquirer

I called up my gift, and looked at Kid Cthulhu with my inner eye. If I couldn’t fight the man, maybe I could fight what was inside him. I used my gift to find the taint, the inhuman corruption deep within his flesh, the thing from Outside that was slowly suffusing his human form. And having found it, it was the easiest thing in the world to rip the taint right out of him.

Kid Cthulhu screamed; and for the first time, he sounded human. He fell to his knees, no longer able to sustain his massive weight once the taint from Outside was gone. He fell forward onto his face, his flesh moving in great ripples of fat. And beside him stood the taint, a horrid twisting shape that made no sense at all in only three spatial dimensions. It howled its fury, in a voice I heard more with my mind than my ears. It didn’t belong in this world, stripped of the host it had been transforming into something suitable to birth its new form. I wondered briefly what that might have been. Nothing like Kid Cthulhu, certainly. It hurt just to look at the taint. Like a colour too vile for our spectrum, a shape like a living Rorschach blot that suggested only nightmares. Its very presence in this world was like fingernails scraping down the blackboard of my soul. -The Unnatural Inquirer

The "Entities from Beyond" who appear in The Bride Wore Black Leather are confirmed to be Outsiders at the end of the book. When John opens a gateway to their world, this is what he sees:

And I raised my gift one last time and reached out with my mind, to find the Entities from Beyond, the Aquarians, or whatever the hell they really were. It took everything I had left, every last bit of hoarded strength. Blood coursed down my face, from my eyes and my nose. It ran from my ears, and spilled from my slack lips. I could feel things bleeding and breaking inside me, important things. I’d pushed myself and my gift further than I ever had before. Too far. No coming back from this. But after everything I’d done, after my lack of faith in those who’d loved me most, how could I not? It needed doing, so I did it. That’s always been my job. My legs started to buckle, and Cathy and Suzie moved quickly in on either side to hold me up. They were both speaking to me, saying urgent things, but I couldn’t hear them. I pushed past all the pain, refusing to be beaten by my own weakness, and concentrated on my gift. And I found my way to the Entities from Beyond and the world where they lived.

And once I’d done that, the greater power in St. Jude’s rose and bound all of us, everyone in the church, together; and used us as a focus to open a door between the Nightside and the other place. I couldn’t have done it on my own, but I wasn’t alone. My good friends were with me. In St. Jude’s, where prayers are answered, and miracles can happen.

The gateway lay before us, a great circle cut in the air itself, through which the other reality could be seen. Don’t ask me where it was. Outside; that’s all I can tell you. Not simply another world but another reality. A harsh light blasted into the church through the gateway, thick and foul and somehow spoiled. Far worse than the few drops of light that had spilled through before, pulled through by the Sun King’s presence. This was an alien light, from an alien place, never meant for human eyes. And through that light, that gateway, I could see the other place, so alien as to be almost beyond human comprehension. Think of a whole world, a whole universe, made up of insects crawling over a ball of dung, forever and ever. That’s as close as I can some to describing what I saw there. -The Bride Wore Black Leather
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Limbo and the Overworld

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Lilith provides some information on the nature of Limbo:

"Creating the Nightside, on Earth but not of it, stable but entirely separate, seriously weakened me. My power was much diminished, and the rising major players of that time, some human but mostly not, seized the opportunity to band together and thrust me back out of this reality, and into Limbo. So that they could be truly free, even from my intentions. I don't bear them any malice. Not really. I've outlived nearly all of them. And Limbo wasn't the worst place to be exiled to. Limbo is a place, or not-place, where things only exist in potential. Ideas without form."

"Like the Primal?" I said, just to show I was paying attention.

"Oh, please. They're just chalk-drawings, compared to me. But as an idea without shape or form, I was helpless to do anything. I was trapped in Limbo, unable to open a door into any other realm. Until someone here created an opening I could use. They were trying to incarnate a female principle into physical existence, a part of the Babalon Working, and it was easy for me to push the Transient Being aside and imprint myself upon the summoning. Someone in that group hadn't done his homework properly. He'd left all kinds of openings for a determined mind to take advantage of. And once I'd left Limbo behind, they couldn't keep me out. All the Powers and Dominations that ever were couldn't have stopped me then. -Hex and the City

John's mind is pulled into the "overworld" by the angels from Above and Below, and during the process, he feels "a sensation that might have been flying or falling":

So I sat there in the deep dark shadows, my back pressed against the wall, breathed deeply, and closed my eyes, concentrating. And opened the eye deep in my mind; my third eye, my private eye. Energies swirled within me, rough and roaring, then flowed out of me, rushing off in all directions, lighting up the night so I could See everything. The thunder of a million voices descended upon me, not all of them in any way human, and I had to struggle to focus, to narrow my vision to the one thing I was searching for. The bedlam died away, and already I could begin to sense a direction, and the beginnings of distance. And then Something reached down out of the overworld, snatched my mind right out of my body, and bore it away. There was a sensation that might have been flying or falling, as the alley and the material world disappeared. And I was somewhere else.

The overworld is described as being "the boundaries of the immaterial", from which both Heaven and Hell can be seen:

This time, it was my turn to stand in the spotlight. A light stabbed down from somewhere above me, brilliant and blinding, holding me in place like a bug transfixed on a pin. I felt horribly naked and exposed, as though the light showed up everything inside me, the good and the bad. All around me there was only darkness, a deep concealing darkness, and somehow I could tell it was there to protect me, because I was not worthy or strong enough to see what lay beyond my small pool of light. But I could sense that I was not alone, that to either side of me there were vast and powerful presences, two great armies assembled on an endless unseen plain. There was a feeling of restless movement, and what might have been the fluttering and flapping of wings. My mind, or more likely my soul, had been hijacked. Brought into the overworld, the boundaries of the immaterial. The overworld wasn’t Heaven or Hell, but it was said you could see them both from there.

A voice spoke to me from one side, and it was a harmony of many voices, like a crowd chanting in syncopation, a choir that sang only in descants. My skin crawled at the sound of it. I’d heard such a voice before, in St. Jude’s. It was a powerful, imperious voice, steeped in ancient, unanswerable authority.

“The dark chalice is loose once more, travelling in the world of mortal men. This cannot be permitted. It is too powerful a thing to be abandoned to merely human hands, and so it has been decided that we shall descend from the glory plains and walk in the material world again.”

A second harmonied voice spoke from the other side, rich and complex and full of discords. “Too long has the Unholy Grail wandered at random in the world of mortal men. The sombre chalice, the great corrupter. It must be placed in the right hands and allowed to fulfill its purpose. Its time has come round at last. And so it has been decided that we shall ascend from the infernal plains and walk in the material world again.”

All I could think was Oh shit… -Agents of Light and Darkness

Using the remaining years of John's life, Dead Boy is able to send both himself and John into "the borderlands we pass through between this life and the next", effectively the void between the mortal world and the afterlife which is likely to be the same overworld mentioned above:

"You can still rescue Rossignol, John. I can use your life force to power a magic, to send both of us after her. Into the dark lands, the borderlands we pass through between this life and the next. When I died and came back, the door was left open a crack for me. I can go after her, but only a living soul can bring her back again. I won't lie to you, John. You could die, doing this. We could all go through that final door and never return. But if you're willing to try, if you're willing to give up all your remaining years in one last gamble, I promise you, we have a chance." -Nightingale's Lament

Time within said void is either frozen or nonexistent altogether, as Dead Boy states that the two of them will return to the mortal plane at the exact moment they leave:

"You can really do this?" I said.

"I told you," said Dead Boy. "I know all there is to know about death."

"Ah, hell," I said. "I never let a client down yet."

"An attitude like that will get you killed," said Dead Boy.

"What if the Cavendishes attack us while we're gone? Destroy our bodies, so there's nothing left to come back to?"

"We'll be back the same moment we left. Or we won't be back at all."

"Do it," I said.

Dead Boy did it, and we both died. -Nightingale's Lament

When we see said void for ourselves, it is described as being "the absence of everything", and contains suspicious similarities to Limbo. Namely, John exists within the void as nothing but a presence without shape or form, speaking without a voice and hearing without sound:

Powered by all the remaining years of my life, Dead Boy and I went into the dark together, and for the first time I discovered there is a darkness even darker than the Nightside. A night that never ends, that never knew stars or a moon. The coldest cell, the longest fall. It was the absence of everything, except for me and Dead Boy. I was just a presence, without form or shape, a scream without a mouth to limit it, but I calmed somewhat as I sensed Dead Boy's presence. We spoke without voices, heard though there was no sound.

There's nothing here. Nothing ...

Actually there is, John, but you're still too close to life to be able to appreciate it. Think yourself lucky. -Nightingale's Lament

John perceives no directions while in this void, and has to think of the darkness as a tunnel leading towards a light in order to make sense of where he's going and approach the afterlife alongside Dead Boy:

Where's Ross?

Think of the darkness as a tunnel, leading us to a light. A way out. This way...

Yes. . . How can there be a direction when there's nothing. . .

Stop asking questions, John. You really wouldn't like the answers. Now follow me.

You've been this way before.

Part of me is always here.

Is that supposed to make me feel better? You're a real spooky person, you know that?

You have no idea, John. This way. . .

And we were falling in a whole new direction. It did help to think of the darkness as a tunnel, leading somewhere. We were definitely approaching something, though with no landmarks it was impossible to judge our speed or progress. I should have been scared, terrified, but already my emotions were fading away, as though they didn't belong there. Even my thoughts were growing fuzzy round the edges. But then I began to feel there was something ahead of me, something special, calling me. A speck of light appeared, beautiful and brilliant, all the colours of the rainbow in a single sharp moment of light. It grew unhurriedly, a great and glorious incandescence, yet still warm and comforting, like the golden beam from a lighthouse, bringing ships safely home through the long lonely nights. And then there was another presence with us, and it was Rossignol. -Nightingale's Lament

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Heaven, Hell, Angels and Demons

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As shown in the quotes regarding Limbo, angels exist in Heaven and Hell, both of which are located beyond material space and are visible from the overworld. When John, Dead Boy and Julien Advent attempt to summon an angel using a ritual, it's revealed that Heaven is beyond every level/dimension of reality in a direction that can only be described as "above, in all senses of the word" and that an angel has to undergo a process of "downloading itself into a mortal frame" in order to interact with the material world:

Julien helped me clear away the throw cushions and the rugs to reveal the bare floor-boards beneath, while Dead Boy went downstairs, and came back with a bucket full of the Beadle’s blood. He handed it over sulkily, muttering something about how he’d been saving that blood, to make blood pudding and stock later. I ignored him and had Julien prick his thumb and add a few drops of his own blood to the bucket, to purify it. (Working on the principle that some trace of the drug that brought out his best elements was still in his system.) I then used the blood to draw a really big restraining circle, surrounded by every protective symbol I knew. It took a long time and used up most of the bucket of blood.

“I don’t even recognise some of the languages you’re using,” said Julien.

“Think yourself lucky,” said Dead Boy, and I had to agree.

Finally, it was done. It looked pretty impressive, even if it did smell really rank. The three of us sat down together, inside a second smaller protective circle, holding hands; and that was it. No chanting, incense, dead chickens, or waving your hands around. In the end, most magic is really primarily a matter of will and intent. The signs I’d so carefully daubed were the spell’s address, along with a few extra things to get the recipient’s attention, and a few safeguards so the recipient couldn’t simply wipe us all out for interrupting them at a particularly inconvenient moment. You’d be surprised how many demons screen their calls these days. Everything else was down to me, Julien Advent, and Dead Boy, and our combined will and determination.

“Something’s happening,” said Dead Boy, after a while. “I can feel energies forming all around us. I can See… I can See avenues opening up, levels of reality unfolding like the petals of a flower, more levels, more and more… I can See further than I ever could before… and I don’t like it. It scares me. It’s too big…”

“Look away,” I said sharply. “Shut down your Sight and reinforce your mental barriers. Concentrate on the summoning.”

“I can feel something,” said Julien.

“Don’t,” I said.

Dead Boy and Julien both had their eyes squeezed shut now, beads of sweat standing out on their strained faces. I kept my eyes open. One of us had to, and I was more used to Seeing the unseen realms. I still kept my mental barriers firmly in place. There were things none of us could afford to see, if we wished to remain in the mortal world. The glory of the shimmering plains is not for mortals. By now we could all feel Something approaching, from a direction we all instinctively recognised but couldn’t identify. It felt like above, in all senses of the word. Something was coming into our world, Something impossibly large and powerful, downloading itself into a mortal frame that wouldn’t blow all the fuses in our merely human minds. -Sharper Than a Serpent's Tooth

Meanwhile, Hell is described as "the place beneath all places":

“Hurry!” howled Jeremiah, fighting to be heard over Hobbes’s screams. “He’s coming!”

I could feel it. Something huge and unspeakable was rising inexorably from the place beneath all places, come to claim what was his. We had to get out while we still could. Between us, Melissa and I got the others moving. The stone floor was rocking and breaking apart under our feet. A terrible presence was beating on the air, and none of us dared look back. Jeremiah was still laughing, and Mariah was screaming in horror. I pushed the Griffin family through the cellar door. And suddenly we were standing in the courtyard, outside the front door of Griffin Hall, and there was Sister Josephine with the Hand of Glory held out before her. -Hell to Pay

After John's gift is shut down by an outside force, he states that only a being from Heaven or Hell would be powerful enough to perform such a feat:

I concentrated, opening up my inner eye, my third eye, my private eye, and my Sight came alive as my gift manifested, showing me all the things in the conference room hidden from everyday gaze. There were ghosts all over the room, men and women reliving the moments of their murders over and over again, trapped in endless loops of Time. Jeremiah had been busy here. I grabbed his hand so he could see them, too, but his face showed no emotion. There were other creatures, too, not in any way human, but they were only passing through, using our dimension as a stepping-stone to somewhere else. They’re always there. And finally I got a glimpse of Melissa, running through the conference room. I couldn’t tell if she was running to someone, or from someone. Her face was cold, focused, intent.

And then my Sight was blocked and shut down by some outside force.

I staggered backwards, and almost fell. My Vision of the greater world was gone, closed off from me. I fought to force my inner eye open again, to See Melissa again, and was shocked when I discovered I couldn’t. This had never happened to me before. Only some incredibly powerful force could shut down my gift, like one of the Powers or Principalities. But that would mean the involvement of Heaven or Hell; both of whom were supposed to be barred from intervening directly inside the Nightside. -Hell to Pay

While still unbelievably powerful, angels are mentally diminished by the act of becoming material:

I'd seen this kind of limited thinking before, back during the angel war. Angels of either House were always much diminished by being made material. They were still unutterably powerful, and their very nature made them unwavering in their purpose, but you couldn't argue or reason with them. Even when conditions had clearly changed so much that their original purpose was no longer relevant. -Paths Not Taken

Angels take their forms directly from the minds of those who view them:

"We want you," said the angel of light. Its words rang in my head like silver bells.

"We want you to stop Lilith. We can help you," said the dark angel. Its words stank in my head like burning flesh.

"I am Gabriel."

"I am Baphomet."

"This is not how we really are," said Gabriel. "We found these images in your heads."

"Comfortable fictions," said Baphomet.

"Designed to make you comfortable with our presence."

"But not too comfortable. We are the will of Heaven and Hell made flesh, and we have been given jurisdiction in this matter." -Paths Not Taken

Enochian, a language designed to allow communication between humans and angels, is stated to be "corrosive to rational thinking":

Etched into every crystal facet were characters from the language known as Enochian, a tongue created for men to speak to angels. I recognised it, but I couldn't read it. Not many can. It is corrosive to rational thinking. -Hex and the City

Mr. Bones states that nothing in the material world can stand up to the angels:

“There are angels in the Nightside,” said Mr. Bones, grimacing as though he’d tasted something bitter. “Ranks and degrees far greater than us. They are death and destruction; the will of the Highest and the Lowest made manifest in the mortal world. Nothing material can hope to stand against them.” -Agents of Light and Darkness

Magic powerful enough to make "the fabric of the world shake" doesn't even slow the angels down:

Judgement Day had come to the Nightside, and it wasn’t pretty. There was gun-fire all over the place, and fiery explosions, and now and again I felt the fabric of the world shake as some poor desperate fool levelled heavy-duty magics against the invading angels. Nothing stopped them, or even slowed them down. Grey men in grey suits stood unnaturally still in doorways, or looked out of alleyways, or walked untouched out of fire-gutted buildings. They were everywhere, and people ran howling before them, driven like cattle to the slaughter. -Agents of Light and Darkness

Beings which may or may not be Outsiders are compared to angels in terms of their age and threat level:

Further off in the night, in a direction that could not be named or pointed to, there was a sound like a great engine slowly turning, as older, darker, more powerful presences began to wake, to defend the Nightside. They stirred in ancient vaults, or long-forgotten graves, creatures and beings of power and legend, some of them almost as old as angels, and as dreadful.

The Nightside is an old, old place. -Agents of Light and Darkness

As shown in the section regarding the Outsiders, angels can effortlessly send people across time:

And once I was locked on to that terrible place, the angel tore me loose from the Present, and sent me rocketing forward through Time. The world speeded up around me, Time flashing by impossibly fast. Days became months became years, piling up behind me. I saw the Nightside fall, its great buildings crashing down, crumbling like sand castles in the path of an oncoming tide. I saw the great oversized moon in the night sky explode, its pieces raining down like fiery meteors. And I saw the stars start to go out, one by one by one. -Sharper Than a Serpent's Tooth

Angels can amp mortal beings by possessing them.

"We can make you powerful," said Baphomet. "Powerful enough to deal with Lilith as she deserves to be dealt with."

"How?" I said.

"By possessing you," said Gabriel. -Paths Not Taken

We went back to the angels. "Explain exactly what you mean by possession," I said. "And be really, really convincing that this is necessary."

"We will not be controlling you," said Gabriel. "We will merely inhabit your bodies to grant you our power."

"One of us, in each of you," said Baphomet. "Your human nature will carry our power into Lilith's city, and together we shall bring her down."

"You will enable us to carry out our mission. And afterwards, we shall leave your bodies, and return you to where you belong." -Paths Not Taken

After Baphomet possesses John, he gains access to new senses in addition to all five of his previous ones, the latter of which are enhanced to vastly superhuman levels. He likens the experience to "being plugged into the energy that runs the universe", feels as if he could tear the material world apart with his bare hands, and outright knows that he now has the ability to reinvigorate dying stars and speed up the planets' orbit around the Sun:

Without any warning, both angels stepped forward and into us, like swimmers diving into deep water. Suzie and I both cried out, more in surprise than shock, and as quickly as that it was done. Baphomet was in my mind, like an idea out of nowhere, like a memory I'd forgotten, like an impulse from a place I normally kept heavily suppressed. And with the angel came power. It was like being plugged into the energy that runs the universe. I could see for miles, hear every sound in the night, and every movement of the air on my skin was like a caress. Suddenly I had other senses, too, and all the worlds within the world, and above and beyond it, unfolded all around me. I was drunk with knowledge, raging with power. I felt like I could tear the whole material world apart with my bare hands. That I could lay waste to any enemy, or dismiss them with a look. I knew that I could breathe life into dying suns, speed the planets in their orbits, dance the dance of life and death, redemption and damnation. -Paths Not Taken

With the power of angels fueling each of them, John and Suzie completely demolish several of Lilith's children. Not only are they now strong enough to rip these beings apart with ease, but their mere gaze and will are powerful enough to melt some of them and completely banish others from the material world:

The creatures rushed us, attacking from every side with tooth and claw and barbed, ripping tentacle. They hated us, just for what we were. For our having dared to enter the place that Lilith had assured them was safe from outside interference. Huge and monstrous, fast and strong, they came at us, death and destruction made flesh, hate and spite and bitter evil given shape and form. They never stood a chance.

Suzie and I looked at them with the power of angels in our eyes, and some of the creatures melted away under the pressure of that gaze, not strong or certain enough to withstand our augmented will. The flesh slipped from their bones like mud and splashed on the ground. Others simply disappeared, banished from the material world by our overwhelming determination. But most stood their ground and fought. They cut at us with claws and barbs, and mouths snapped all around us, while spiked tentacles sought to enwrap or tear us apart. We took no hurt. We were above that. We grabbed them with our strong hands and tore them limb from limb. Our fists punched through the hardest flesh and shattered the thickest carapaces. We crushed skulls and punched in chests and ripped off arms and legs and tentacles. More creatures came running, from every direction at once, spilling and bursting out of every adjoining street and alley. They outnumbered us a hundred to one, a thousand to one, living nightmares and killing machines of unnatural flesh and blood, every shape and form that darkness could conceive.

But Suzie and I had angels within us, and we were strong, so strong. -Paths Not Taken

The carnage continues, with John and Suzie obliterating more and more of these creatures with ease, even splattering some of them with nothing but their gaze:

The street beneath our feet broke apart as awful things burst up out of the earth beneath the city. They wrapped around our legs and tried to drag us down. Bat-winged things slammed down out of the night sky, to tear and rend or snatch us up and carry us away. Suzie and I fought them all, our fingers sinking deep into yielding flesh. We picked creatures up and threw them away, and they crashed into elegant walls and brought down tall buildings. We walked steadily forward, and nothing could stand against us. The dead piled up everywhere, and the wounded crawled away, cursing and weeping and calling out for their mother. Wherever we turned our gaze or our hands, monstrous forms broke or faded away, and some splashed like bloody mud in the streets. Finally, the survivors turned and ran, disappearing back into the centre of the city, back to the dark heart of the Nightside, where Lilith waited for us to come to her. Suzie and I walked through the dead and the dying, the dismembered creatures and the splintered carapaces, ignoring the wounded and the weeping. They were not why we were there. -Paths Not Taken

An angel threatens to rip out a man's soul and fling it straight into Hell:

There was something standing in the doorway now, something darker and deeper than the shadows. I could feel its presence, its pressure, like a great weight in the night, as though something huge and dense and utterly inhuman had found its way into the human world. It didn’t belong here, but it had come anyway, because it could. The odd, whispering voice spoke again.

“Give it to us. Give it to us now. Or we will tear the soul out of your body and throw it down into the Pit, there to burn in the flames of the Inferno forever.”

(Contextually speaking, this was probably an angel from Below, but it's likely that angels from both sides can do this)

An angel's mere presence can completely shut off lesser powers:

A vivid, overwhelming presence suddenly filled the restaurant, slapping up against the walls and suppressing everything else. The Bedlam Boys’ power snapped off in an instant, blown out like four tiny candles in a hurricane. They just stood there and blinked stupidly at the angel. At first, it looked like a grey man in a grey suit, so average-looking in every way as to seem almost generic. You couldn’t quite look at him, only glimpse him out of the corner of your eyes. And then he grew more and more real, more and more solid, more there, until you couldn’t look at anything else. The angel lifted his grey head and looked at the Boys, and suddenly erupted into a pillar of fire in human form. -Agents of Light and Darkness

As you'll note from what the angel-possessed John and Suzie were capable of, angels can freely manipulate matter. This also allows them to turn people into salt:

His light was blinding, dazzling, too bright to look at directly. Vast glowing wings spread out behind him, sparking and spitting. There was a stench of ozone and burning feathers. The Bedlam Boys stared into the heart of that terrible light, mesmerized.

And turned to salt.

One moment they were living and breathing people, and the next there were four salt statues, paler than death, still wearing their stupid spangled jumpsuits. And all four fixed white faces were screaming horribly, silently, forever. The franchise’s staff and customers, freed from their imposed fears, now had something real to be afraid of. They screamed and howled and ran for the open door. I hauled Suzie back out of the way as they stampeded past us, fighting and clawing each other in their need to get away. I felt very much like joining them. The sheer presence of the angel was viscerally disturbing, like every authority figure you ever knew was out to get you, all rolled into one.

I’ve never got on well with authority figures.

The angel gestured with a brightly glowing hand, and one of the salt statues toppled over and shattered. -Agents of Light and Darkness

A great shadow leapt forward out of the doorway, rushed down the aisle, and enveloped the man in black before he even had time to cry out. I pressed my back against the cold stone wall, praying for my shadows to hide me. There was a great roaring in the church; like all the lions in the world giving voice at once. And then the shadow retreated, seeping slowly back up the aisle, as though … satiated. It swept through the open doorway and was gone. I couldn’t feel its presence in the night any more. I stepped cautiously forward, and studied the figure still crouching before the altar. It was now a gleaming white statue, wearing a tattered black suit. The white hands still held the rejected chalice. The frozen white face was caught in a never-ending scream of horror. -Agents of Light and Darkness

John states that angels can take people apart "right down to the molecular level", and keeping them alive while doing so:

He slapped the gun aside and glared right back at her. “Don’t you threaten me, Shooter. I’m protected in ways you can’t even imagine.”

“Unfortunately, he probably is,” I said. “So ease off a little, Suzie. Collector, in case it’s slipped your attention, we are currently surrounded by whole armies of angels, all of whom would be quite willing to take you apart, right down to the molecular level, while still keeping you alive and aware and screaming horribly if that’s what it takes to get you to hand over the Unholy Grail. Only Merlin’s power is holding them back, for the moment. You really think your protections are good enough to hold off a whole bunch of really angry angels?” -Agents of Light and Darkness

One of the...weirder moments from earlier in the same book may or may not confirm this. This was what the angels did to Count Video after they finally found a way past his binary magic:

Something moved in the street ahead, and I stumbled to a halt. Suzie saw it too, and crashed to a halt just ahead of me, automatically bringing her shotgun to bear. Two dim figures came running down the street towards us, silhouetted against the fires burning behind them. They both looked…wrong, somehow. And then the skin of Count Video came flapping down the street, raw and empty, with his flayed body running weeping after it. Suzie and I drew back to let them pass. There was nothing we could do.

“I don’t think the city resistance is faring too well,” I said, trying hard to sound calm. -Agents of Light and Darkness

There are various types of demons, of differing rank and station. Some are weak enough for beings like John Taylor and Dead Boy to harm with their bare hands, while others are absurdly powerful to the point of being vaguely comparable to angels. These next quotes will focus on the latter group.

Succubi are a type of fallen angel who've remade themselves into demons of lust, and as seen with the succubus Pretty Poison, they're perfectly capable of fighting and even killing the more standard angels if they want or need to:

"Her name translates from the original Aramaic as Pretty Poison," Sinner observed calmly. "There are some quite specific verses about her in the Dead Sea Scrolls, none of them complimentary. In the War against Heaven, she killed more than her fair share of angels, and even she doesn't remember how many men she destroyed as a succubus, in her war against Humanity. Watch your manners around her, and never turn your back on her. I love her dearly, but she's still a demon. And by the way—she's the only one who gets to call me Sidney." -Hex and the City

Like the angels, succubi take their forms from the minds of those who view them. In their case, they take the form of what the viewer secretly desires the most:

"Allow me to introduce you," said Sinner, in his soft patient voice. "This is my girl-fiend. The demon succubus I fell in love with, all those years ago. I have no idea what you see when you look at her, because it is her nature to appear to everyone as the image of what they secretly most desire." -Hex and the City

Succubi (and presumably other angels) are completely unaffected by magic, to the point that they can catch projectile spells right out of the air and even eat them without harm:

Other magics homed in on Pretty Poison, who snatched them out of mid air and ate them up, grinning like a naughty schoolgirl. She was a fallen angel and older than the world, and the minor magics of men were nothing to her. -Hex and the City

Pretty Poison can use the Infernal Realms to transport herself and others anywhere she wants, and more or less states that every other member of her kind can do the same:

"I know a way we can get to Uptown," Pretty Poison said unexpectedly. "I can take us straight there. If that's what you want, Sidney."

"Well, of course," said Sinner. "But I didn't know you could..."

A halo of flies sprang up around Pretty Poison's head, buzzing loudly. Vicious claws thrust out of her elegant fingers as she traced fiery sigils on the air. Her face disappeared into shadow, in which two sullen red glows burned. I actually fell back a step. Madman just looked at her sadly.

Pretty Poison said something that hurt our ears to hear it, and a circle of hell-fire sprang up around all of us. Sulphur yellow flames that stank of brimstone, though the heat couldn't reach us. The flames leapt high, then died down again, and as quickly as that we were Uptown. The flames snapped off, and Pretty Poison looked like a woman again. I shook my head, disoriented. Just then, in the moment of transition, it seemed to me that I had heard uncountable voices, crying out in torment... I looked at Pretty Poison, who smiled back demurely.

"I didn't know you could do that," said Sinner, framing his words with what I thought was considerable calm, under the circumstances.

"Just a quick side-step through the Infernal Realms," said Pretty Poison. "After all, I am a demon succubus, Sidney darling. We have to be able to get absolutely anywhere; it's in the job description." -Hex and the City

Succubi (and presumably other angels and demons) can tell whether a being is mortal, heavenly or demonic, just by looking at them:

"Human?" said the Lamentation, not bothering to hide the scorn in its voice. "Such a little thing to be. I am large and glorious. I have always been here, and always will be."

"Nonsense," Pretty Poison said briskly. She stepped forward to stare closely at the twisted thing in its cage. "You're not one of my kind. You were made, not created, this way. The world, or your own desires, made you what you are. There is nothing of the eternal in you, nothing of the Infernal or the Elect. You're just meat, with meat's needs and delusions." -Hex and the City

Like the more typical angels, succubi can shut off powers with ease. In this case, Pretty Poison shuts off the powers of Bad Penny, a character who possesses a glamour that, when activated, makes her so attractive that those who see her will do anything for her.

"Oh dear," said Bad Penny. "How sad. Fallen in with bad company again, I see. What am I going to do with you, John? I know! I'll kill you right here and now. And just to keep everything neat and tidy, your friends can die with you." She turned her powerful smile on Sinner. "You disapprove of John, don't you? How sweet. Perhaps you'd like to break his neck for me? I'd really like that. In fact, I'd like it if you all beat each other to death, right in front of me."

And just like that, she was suddenly the most attractive woman in the world. Her sexuality blazed like someone had just opened a furnace door. Her presence filled the street, impossible to look away from, impossible to resist. To see her was to want her, to need her, more than life itself. I had my gift, and Bad Penny had hers. She had become the woman you'd do anything for, including murder. Her greatest weapon had always been herself. No-one could resist her body, once she'd turned it up to eleven. Except... for all our special abilities, Sinner and Madman and I were just men, while Pretty Poison was a demon succubus from Hell.

"Amateur," she said.

And just like that, the spell was broken. Bad Penny's glamour snapped off, and she was just another really good-looking woman with a bit of a weight problem. She looked at us, open-mouthed, absolutely dumbfounded. I don't think anyone had ever broken her spell that easily, that casually, before. -Hex and the City

If a succubus (or, likely, any other angel of darkness) remembers the angel they had once been prior to their fall, they will be reborn as an angel of light:

Pretty Poison knew all this. Knew that Sinner's stubborn love for her would have him stand there for as long as his will could hold him up, and perhaps beyond. All to protect her. And in that moment, she knew she couldn't allow that. Couldn't allow the man who had suffered so much on her account to sacrifice everything for her. He mattered more than she. And so she stepped out from behind him, and stepped in front of him, to protect him with her body. Finally understanding the meaning of love, and self-sacrifice. Loving him as he loved her.

There was a blast of incandescent light, bright and glorious, as Pretty Poison remembered the angel she had once been, before the Fall. All her old evils were burned away, transfigured by the power of her love, and she became again the angel she had once been, fit to take her place in Heaven. She was too bright to look at, and we all turned our heads away, but we could still hear the slow, heavy beating of mighty wings.

"Come with me, to Paradise," said the angel to the man called Sinner. "For you have been found worthy, as have I."

The light flared up unbearably, then died away, and they were both gone. -Hex and the City

Like angels, the highest-ranking demons' true forms are too much for human minds to handle, and when transforming in the material plane, their bodies twist in a manner that defies geometry:

“Enough,” I said. “We’re well past the time for civilised conversation. Show me your real face. Show me what you really are.”

He laughed at me. “Your limited human mind couldn’t cope with all the awful things I am. Just one glimpse of my true nature would blow your little mind apart. But there is a shape I like to use, when I am summoned to this dreary mortal plane…”

He stretched and twisted in a way that had nothing to do with the geometries of the material world, and in a moment Hobbes was gone and something else was standing in his place. Something that had never been, never could be, merely human. It was huge, almost twelve feet tall, bent over to fit into the stone-walled cellar, its horned head scraping against the ceiling. It had blood-red skin covered in seeping plague sores and great membranous batwings that stretched around it like a ribbed crimson cloak. It had cloven hoofs and clawed hands. It was hermaphrodite, with grossly swollen male and female parts. It stank of sulphur and suffering. And its face…I had to look away for a moment. Its face was full of all the evil and pain and horror in the world. -Hell to Pay

----

Transient Beings

----
Transient Beings are the living embodiments of abstract concepts:

The vision changed again, to show us the Babalon Working. Only edited highlights, of course, but it was still pretty impressive. The lengthy ritual was designed to summon, hold, and physically incarnate one of the Transient Beings; not just a demon or spirit, but one of the real Powers and Dominations. The living embodiment of an abstract concept, in this case love or lust or sexual obsession. (Babalon was an old, old name, and no two sources could agree on exactly what it represented.) The three young men saw it only as a weapon they could use against those they perceived as the villains of the day, and those in the Authorities who might try to obstruct the forthcoming changes. The three young men were determined not to be stopped. They would bring about freedom by force, if necessary. Like most fanatics, they were blind to irony, and even if they had seen it, they probably wouldn't have cared. They were doing this for the greater good, after all. -Hex and the City

(As you'll notice from this quote, the Transient Beings' true forms exist in Limbo. Refer to the corresponding section for more information on that.)

Despite their sheer power, a Transient Being is limited to the concept they embody:

I looked at her thoughtfully, taking my time. Lady Luck was one of the Transient Beings, a physical incarnation of an abstract concept, or ideal. Appallingly powerful, but limited to the role she embodied. -Hex and the City

Transient Beings are immortal due to their existence as concepts:

"You," she said, pointing to a single figure at the front of the pack. "I don't know you. You're not one of mine. What are you?"

The Engineer stared calmly back at her, while everyone else edged away from him. He was squat and broad and only vaguely humanoid, with blue steel shapes piercing blue flesh, and long strips of bare muscle tissue held together with bolts and springs. Steam hissed from his naked joints, his eyes glowed like coals, and if you got close enough you could hear his heart ticking. He was surrounded and protected by a group of gangling metal constructions, of intricate design and baroque sensibilities, though whether they were the engineer's worshippers or his creations was unclear.

"I am a Transient Being," said the Engineer, in a voice like metal scraping against metal. "A physical incarnation of an abstract idea. I am immortal because I am a concept, not because I have your unnatural blood in my ancestry. The world has become so much more complex since your time, Lilith. All of this… is none of my business. So I'll leave you to get on with it." -Sharper Than a Serpent's Tooth

Transient Beings can "walk sideways out of reality", disappearing down a direction that mortals can't even name:

He turned and walked sideways from the world, disappearing down a direction most of those present couldn't even comprehend, let alone identify, and in a moment he was gone. The steel-and-brass constructions he left behind collapsed emptily, so much scrap metal littering the ground. Lilith stood silent for a moment, nonplussed. That hadn't been in the script. -Sharper Than a Serpent's Tooth

The above Being, the Engineer, is implied (albeit never outright stated) to embody the concept of technology, and is the one responsible for the technology which gives Count Video his powers:

And just like that Count Video was there in the office with us, as though he'd always been there, but we hadn't noticed him. The man himself, wrapped in shifting plasma lights, tall and pale and ghostly in his tattered black leathers, his colourless skin studded with silicon nodes and sorcerous circuitry. Heavy black stitches and metal staples held his skin in place. Whoever had reattached it, after it was flayed from him during the angel war, had done a good job. Though his face did look a bit taut, his thin-lipped mouth pulled into a constant mirthless grin. His hands twitched at his sides, eager to weave binary magics and rewrite probabilities. He did so love to show off what he could do. Count Video had no natural gift for change magic; he'd made himself the way he was through dedicated research into the more insane areas of quantum physics, and a little help from a Transient Being.

He's supposed to have had sex with a computer. The things a scientist will do for knowledge. -Paths Not Taken

He heard the threat in my voice and stood up abruptly, pulling his power about him. Plasma lights sparked and scintillated all around him, and the sorcerous circuitry embedded in his flesh glowed with an eerie light. Anyone else would probably have been impressed. But for all his magic, Count Video was really quite limited. All his power came from the terrible technology implanted in his body by the Transient Being known as the Engineer, and Tristram had never really appreciated its potential. He used it to see possible futures, like a video junky flipping endlessly from one channel to another. That was how he got his name. And with all those other Eamonns out there in the Nightside, draining his energy, he had to be running low on power by now. All I had to do was keep him busy, and his clockwork would run down.

Assuming he didn't manage to kill me first, of course. -Paths Not Taken

This is what said technology allows him to do:

"Tell me what you've been doing to Eamonn," I said. "You know you want to."

"Don't mind if I do," said Count Video, settling himself comfortably as he switched to lecture mode. "For everyone else, alternative timetracks are only theory. But to me, every time-line is as real as any other. I see them all, flowing past me like so many rivers, and I can dip a toe into any of them I please. Sometimes I go fishing, and pull out all kinds of strange and useful things. Like all those variant editions of Eamonn Mitchell. All the people he was and might have been, if only things had gone a little differently. I scattered them across the Nightside, armed them with wands charged by my probability magic, and sent them after your client. Most never got to him, of course. The Nightside is such a dangerous and distracting place."

"Yes, but why wands?" I said.

Count Video shrugged. "When dealing with amateurs, keep it simple." -Paths Not Taken

The powers granted to Count Video by the Engineer allowed the latter to fend off angels for a brief period of time. He's eventually overwhelmed by them (as noted in the section regarding Angels), but this is a notable feat nonetheless:

Count Video leaned casually against a lamp-post, wrapped in static and shifting plasma lights, his pale skin studded with silicon nodes and sorcerous circuitry. He sniggered nastily as his long-fingered hands weaved binary magic, rewriting reality with applied description theory and insane mathematics, and the angels couldn’t get anywhere near him. -Agents of Light and Darkness

While all Transient Beings embody some sort of concept, not all beings who embody a concept are Transient Beings. As an example, Old Father Time is believed to the concept of time itself, given human form to interact with the world of men. Yet he is not a Transient Being:

"If we could stick to the subject at hand," the sphere said loudly. "We will not discuss Shadows Fall because it makes the head we don't have hurt even worse than Time-slips. Some concepts should be banned, on mental health grounds. Let us discuss Old Father Time. An enigmatic figure. No-one seems too sure exactly what he is. An incarnation, certainly, and immortal; but not a Transient Being. Some say he is the very concept of Time itself, given a human form to interact with the human world. Why this was ever considered necessary, or even a good idea, remains unclear. Humans do enough damage in three dimensions, without giving them access to the fourth. Anyway; the one thing everyone agrees on is that he is extremely powerful and even more dangerous. The only person ever to tell the Authorities to go to Hell on a regular basis and make it stick. You don't argue with someone who can send you back in Time to play with the dinosaurs. Well, not more than once, anyway. Old Father Time is a native of Shadows Fall, and still lives there, but he commutes into the Nightside when he feels like it. -Paths Not Taken

EDIT: This proves to be wrong in Nightside Book 6, where Old Father Time himself confirms that he is, in fact, a Transient Being. Quotes surrounding him coming soon.

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Dimensionality in general
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(coming soon, maybe)
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Miscellany
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(ditto)