New Beast design notes

Beasts: The Fucked. Or more officially, the Begotten/Children/etc. Beasts are plucked from their previous lives by the Primordial Nightmare. Exactly what prompts the Nightmare to choose a human to become a Beast is unclear, but the shadow of the Nightmare over their souls is detectable by full Beasts. They suffer nightmares and such more or less as the main document claims, but these tend to not involve wisdom; rather, they mostly revolve around the human being killed by a monster of some sort. Eventually, one of these dreams becomes fully real, and the Devouring occurs; the Horror eats the human's soul and replaces it, and a new Beast is born.

Altered stats: Satiety does not exist here. Beasts have a separate mana stat--Phobos--and morality stat--Synergy (like Sin-Eaters, yes). The point of Synergy is to manage the Horror enough that it can work comfortably alongside the Beast's human self. Indulging or denying the Horror too much will cause Synergy to drop, as the Horror grows stronger and more independent from fattening or hunger. Reaching Synergy 0 can inflict either the Unleashed or Unfettered Inheritances, both of which render the character unplayable.

Guardianship: While Beasts have been crafted by the Primordial Nightmare for the purposes of spreading fear, they eventually discovered an alternative for feeding themselves: guardianship. It's possible for a Beast to designate a person, object or group that they are sworn to protect, and in so doing, they gain precious Phobos. Beware, however, for harm done to one's guardianship can damage one's sense of self... and losing it altogether will shake you to your core.

Beast society: The given collection of Beasts in any one region is known as a pantheon. Governing styles of pantheons vary, but most Beasts prefer a semblance of democracy, as it gives them the most say in keeping their own guardianships, or feeding grounds for the more predatory ones. Of course, it's hardly unheard of for a particularly ferocious Beast to forcibly dominate a pantheon and rule as a tyrant, but Beasts are territorial by nature and tend to lash out if they feel that what's their's is being threatened. More functional pantheons will sometimes build up into mutual protection networks for each other's guardianships. All of a pantheon, ideally, will come together once they notice a Hero in town... unfortunately, noticing a Hero before they've already Entangled a large number of mortals is easier said than done.

The Primordial Nightmare: Imagine a spiritual monster of truly enormous size. Like a living island with its wooden tentacles plunged into the dirt below, sucking the life out of it. That's the Nightmare; it's a living entity, and it feeds on the fears of humanity, a veritable nighthag of the entire species. And it chooses both Beasts and Heroes to serve its purpose (assuming "chooses" can accurately describe this thing's thought processes. Beasts spread fear--at least, that's their intended purpose--while Heroes feed on it.

Heroes: Possibly the Nightmare's feeder tendrils, but it's hard to know for sure. Heroes resemble Beasts in some ways, but are quite different. For one thing, it's a would-be Hero's choice to merge his soul with one of the so-called Guides of the Nightmare; for another, their humanity is gone in an eyeblink (not that there was usually much there to begin with, for someone who might listen to a Guide).
Heroes are the picture of the charming, picturesque psychopath. Their condition gives them a supernaturally compelling aura, one that leads normal people to admire them, and listen to what they say must be feared. And killed. These people are called the Entangled, victims of the Hero's Mythology (the power stat; similar to a Lair, but its "chambers" are human minds), and Heroes milk them for Satiety as the Nightmare slowly drains their will.
Heroes gain Phobos by killing those their Entangled--groups of which are referred to as "crowds," or "mobs" if the Hero uses them as tools in his hunt--fear. This doesn't have to be fear that the Hero induces; showing up as their savior for something they already feared works just as well, and is usually easier (Heroes rarely have strong opinions about human culture anymore, so they're willing to adapt to expectations). However, the premade victims eventually run out, and the Hero then needs to stir fear of more and more targets into the hearts of the crowd.
Heroes may or may not actually hate the Beasts they hunt, but hatred isn't their primary motivation; rather, it's because the act of the kill is incredibly delicious, addictive and empowering, basically akin to diablerie. Their Phobos is instantly filled to 10, and it's a prerequisite for increasing their Mythology; it also can lead to instant boosts in their other powers.
The Entangled are pretty boned. If a Hero is killed, that (with one exception) releases them, but they have no other real recourse for freedom. Also, as the Hero exploits them, the Nightmare feeds on them; Entangled gradually lose dots of Willpower. It manifests as increasing devotion to the Hero with dwindling interest in life outside the crowd. When Willpower hits 0, the Entangled's self effectively dies; all that's left is a mindless automaton that can only obey the Hero. This isn't entirely good for the Hero, either, as they no longer fear anything and aren't part of the Mythology, per se; that's why Heroes have to keep attracting more and more cronies. Willpower will slowly recover if an Entangled is released.
One thing that Beasts can get out of Hero fights is the ability to eat the Hero's soul, such as it is. A reversal of the Hero's own kills, it's just as glorious an experience for the Beast, and gives an automatic extra dot of Lair. However, it comes at a price: every single Entangled in the Hero's Web drops dead from the psychic shock. Aside from the human cost, this tends to be quite bad for avoiding attention, since none of the corpses will show any signs of what killed them.