These are places of death, torture, and constant warfare. And yet, death cannot touch those who already die. Which makes this also an orgiastic place of difference and struggle that lets the strongest rise and relegates the fallen to greater refinement through the flames of purity.
In the past, the hells were 9 realms, each ruled by a lord demon and each ruled in turn by the masters of the hells. They were solid, structured, and set in place by motion and time immemorial. Since the Age of Wonders, that unity has shattered, and now there are an infinite number of hells ruled over by an infinite number of demons. Every contingency of belief is accounted for