mostly pride ring focused!
hell used to be all torture chambers and classic fiery suffering until the imps unionized and went on strike in the 13th century
sinners can't die but their bodies do eventually give up on regeneration and they become part of the landscape (that's why there's so many eyes)
when sinners first manifest it's in a bland government building. they are given their form of ID (time of death, name, age, status of soul) before exiting through one of the many elevators across pride.
soul markets, auctions, and soul casinos. husk ran soul casinos as well as typical gambling fair, which is how he became an overlord.
the vees delegate their deals. meaning they have souls who own souls. this is a new business management strategy, and partly why they're so successful
sinners' appearances tie directly into insecurities, fears, and way of death. because of this it's rude to ask why a sinner looks how they do
when a sinner has a specific spot marking them where they died, it's called 'lucifer's mark' or a 'butcher's mark'
there are two seasons in hell. growing and decaying season (both are unreasonably hot). in decaying season, expect animals and sinners to shed limbs, contract rabies, and start starving for no particular reason! in growing season, enjoy your kitchen growing fungi and everything that shouldn't have eyes gaining, you guessed it, too many eyes. also expect temporary sentience to inanimate objects.
there are pride ring accents. in the 7th century there was an entirely sinner-unique language which 65% of the population spoke, which is now lost to time
there are marriage soul contracts! a lot of them are insane or overtly one-sided 'til death do us part stuff, and sometimes they can be triggered by vague street deals or accidental wording
the river styx is real and connects to envy's ocean. get dunked in it and you lose all your memories from your life in hell
the sinner reformation movement in the 15th century introduced sinner ruling of pride, overlords and hell's hierarchy we know now
to be considered a modern overlord, you need control over a domain (ex. radio, television, scam call centers) and a recognition seal from royalty (usually lilith). this makes alastor not technically an overlord, but everyones too scared to kick him out of the meetings