Re: Hell in Dungeon Fantasy
 

Maybe the demons see the suffering they inflict on the damned as deserved, and regard themselves as the cosmic force of true justice. Justice without mercy, without sentimentality, without patience for human frailty or hope of reform. Endless retribution.

If you want them to be somehow opposed to the gods, then perhaps the demons have decided that even the gods have commited crimes and must be punished or purged.

Re: Hell in Dungeon Fantasy
 

That could be sad as they don't understand why they're loathed by the gods. They think they're doing what's right, but without empathy or sympathy, no law is truly just. Zero tolerance policies don't work for anyone. ;) (I'm kidding, and not trying to bring in modern issues.)