Editing Geist: The Sin-Eaters (section)

=== Kerberoi ===
The final bosses of the Underworld, for the most part.

A Kerberus, or Kerberoi, are inhuman looking entities who control the Dead Dominions; impossibly ancient, are almost a fundamental force of the Underworld itself, and are keepers and enforcers of the Old Laws; effectively making them demigods inside the deepest parts of the Underworld. They are the reason you do not break the Old Laws inside Dead Dominions; they know instantly whether or not you've done this, and will hunt your ass down to the ends of the Underworld in order to make you pay for it. They have only two saving graces in this regard: They can't really leave the Underworld and don't want to leave their Dominion all that often or for too long, but they have many, many servants and you will be hunted for as long as you can stand or defend yourself by the Kerberoi. Their second grace is that if they catch you; they will ''not'' kill you (most of the time). After all, you can't spread the word about not breaking the law if you died. But you will instead suffer for your crime, suffer in ways you can't imagine or even consider, and your will shatters at any attempt to evade said punishment. And they change in severity and method often: Some Kerberoi have a shitzillion laws that require you to hop on one leg for two minutes and say "I'm sorry" to each passer-by, others might insist on a material payment or recompense...the other ones will crucify you for ten days for breaking the four laws that they've been governing for eons that you couldn't possibly have known about. Being thrown out of the Dominion is probably the ''least'' unpleasant punishment that can happen, and most Kerberoi are not nearly that lenient. 

Oh, and don't bother rules lawyering your way out of it. They've been around the block, they can nail you.

Unless you're absolutely sure you can win, it should be made clear that they have nearly infinite power in their domains, and many of them allow you to exist there on their terms, and the rewards you could gain in their realms are so valuable it's not close to worth it to try and break an Old Law on purpose to gain their attention: Do Not Fuck with the Kerberoi.