opalescent ramblings

The "infinite possible realities" thing is technically true, but the execution is fucky. At some point in the past, some impossibly powerful precursor race basically took thousands of different universes and shoved them together into one "space" (while looking for an entropy-free universe, but shh nobody knows that in-universe), effectively separating this "multiverse" from the overall "megaverse", and it's generally theorized that similar environments can exist naturally as well, but nobody has found a way to observe, let alone travel, outside of this "cluster". So, this means that while there may be many different unique universes with different laws and developments and whatnot, your options are actually shockingly limited, especially since a rough 30-50% of these universes are either too old or too young for anybody to build or harvest anything useful, or else have laws of physics that differ too much from the "baseline" for most creatures to actually continue to exist upon entering. Universes are continually documented and mapped whenever possible, with 27 closely connected "core dimensions" forming the center of interdimiensional civilization. Travel between dimensions is formalized through the "Ways", which are essentially giant fuckoff magical "tunnels" between dimensions that require immense magical, material, and logistical upkeep, kept in place by the Powers That Be for mutually beneficial trade. Virtually all other dimensions require a certain amount of "pathfinding" to travel to, which is highly difficult for all but a few highly powerful mages or gods - tearing open holes in reality or otherwise missing your mark make for very bad experiences.

"Between" dimensions exists a space not truly comprehensible to mortal or god, a cacophony of colors and sounds and sensations, that can be slipped into by accident if a pathfinder isn't careful, or sometimes glimpsed through tears in reality. The one thing that is clearly discerned by god and mortal alike in this space are the screams of anguish and rage, the undeniable fact that *something* there utterly, completely, HATES you and wants to hurt you, violate you, make you suffer and then rip you to shreds; sometimes, if you remain in this space for too long, you can feel its presence coming towards you, and realize there are so many of them as to be uncountable. The ones who don't leave then never do; those who return successfully are forever changed, and say that in the dead of night when they listen to the rustle of the trees and blood rushing in their ears, they can still hear the screams weaved into the very pattern of reality.

Although most universes have some sort of primitive "magicks", most magic systems are entirely unique to their own universe and don't work very well outside of them, and are usually limited compared to "true" magick, a multiversal system which is usable throughout and basically comes down to a vague system of symbolism and sacrifice [think back to that SCP Foundation-inspired magic system I once recommended for Viranos, except slightly more strict]. Note that, with some heavy adaptation, many "native magicks" can be made to work with the multiversal system, if sub-optimally. There is an entire class of beings, "gods", which can preform magick with virtually no cost or preparation, and range from modest nature spirits to incomprehensible interdimensional entities, differing wildly in character, sapience, and ability based on their origins. It should be noted that "magick" is, for the most part, "lost" to many societies once they adopt more "materialistic" processes of thinking and existing, as magick is based heavily upon concepts like symbolism, belief, and mindfulness. As such, there are almost no cases of advanced civilizations "breaking through" into another dimension. Usually, advanced life is smothered in its cradle due to the lack of suitable interstellar travel methods in most universes; the universes that do allow effective interstellar travel (and thus trade and politics) are typically informally isolated by all powers with the authority and means to do so - the odds of these civilizations achieving interdimensional travel are practically nonexistent due to the incompatibility between the mindsets typically required for "true magick" versus sci-fi science, but the sheer amount of resources and manpower these societies can bring to bear could utterly disrupt the interdimensional economic and political landscape if somebody were to 'let them out'.

The political Powers That Be are surprisingly few and restricted, given the scale of the multiverse. It is difficult to speak of "geography" when discussing the multiverse - some demonstrations would have one believe that it was a sort of "bubble" containing many smaller bubbles floating near each other, but the reality is more similar to that of many "rugs" or "blankets" crushed atop one another in many layers, except they all technically exist in the same layer at once. As such, there is really no such thing as geographic space as far as the multiverse is concerned - only the maintenance of the Ways and a retinue of skilled pathfinders dictate "geography". While many powers span many dimensions, it is important to note that most of them 'only' span several planets in practice - the sheer distance between celestial bodies and the inability of even True Magick to create reliable interstellar travel means that only an infinitismally small amount of the space in most universes is ever actually inhabited and utilized.

The Powers That Be include such polities as:

The Tesserarchy - Although frequently referred to under one name, the Tesserarchy is actually four wholly separate polities, each of which spans multiple dimensions and revolves around an immensely powerful god-king: the Ruby King Icath of Tarnash, a being of anger and domination whose realm is built on fear, slaves, and blood rituals; the Amber King Gazan of Adirana, a hedonistic and apathetic lord who allows a merchant-elite that values debauchery and pure profit to run amok in His realm; the Emerald King Yasar of Lyonagh, an entity made of denial and bloat, whose kingdom is in fact a single massive living entity where the dead are not allowed to die and all beings form a part of Him; and the Sapphire King Naryx of Siraz, a mournful, regretful lord obsessed with epistemology and the hoarding of knowledge. Each King is theoretically capable of ending entire worlds on His own when moved to act, but each remains relatively isolated, or else preoccupied with countering one another whenever they do act.

The Talos Foundation - Effectively an SCP Foundation expy mixed with aspects of Cerberus from Mass Effect, and then blown up to control entire planets and dimensions. A quasi-military organization dedicated to Human Supremacy and the containment and destruction of all magicks - especially True Magick - as well as gods, in essence wanting to rewrite the laws of the entire megaverse's reality. They are the most conventionally "advanced" society to achieve regular interdimensional travel, utilizing advanced technology to combat the magical in an effort to enforce the "Prime Reality" across all dimensions where regular humans (think normal, real life humans) form a majority of the population. While it is usually quite isolationist and limited to roughly ~7 dimensions, there is a "bulwark dimension" through which it allows contact and trade with the rest of the multiverse. Despite its small size and lack of magic, it is widely feared for its potential to one day combine magic and technology to exploit the resources of an entire galaxy or beyond and bring it to bear against the rest of the multiverse.

The Orthrus Institute - An organization heavily implied to have some vague relation to the Foundation and originally founded by humans as well, but willingly and enthusiastically incorporating magic and non-humans, with a primarily scholarly mission of collecting and advancing knowledge wherever possible. Organized along the lines of a giant university-state and concentrated primarily in its "capital" in Auranaxus, a pocket dimension based around a Penrose Sphere, it attempts to stay officially neutral in most affairs, but is known for asserting itself to secure valuable artifacts or prevent other factions from achieving some "forbidden" knowledge.


[[[ and this is the point I realized it's probably time for me to go to bed, but I skipped to something interesting anyway ]]]

There exists, in the whispered corners of academia and the echoes of gods' memories, a theory known as the Five Histories. The first is forgotten, the second ended in darkness, the third in agony, the fourth in flames, and the fifth is yet to be written. These histories seemingly describe multiple different chronologies of the multiverse with a beginning and end, with some events seemingly strangely similar but never having  happened, with thousands of pieces that are either not quite correct or outright false to what has been recorded as actually happening, scattered through out-of-place books and artifacts and the ramblings of old forgotten gods. It is implied that these are the remnants of some "higher power"'s observations of the multiverse's single continuous history and attempts to alter it. The First was whatever the precursors who gathered all the universes together did; the Second was when entropy claimed these first universes; the Third was when the universes collapsed into their single "layer"; the Fourth was when the Brass Queen led her coup in Hell and the Tesserarchy rose from seemingly nothing; the Fifth is apparently our current history.