Originally the Greek Furies, in role-playing erinyes are Hell’s fallen and avenging angels. It’s tempting to think of them as Hell’s succubi, but where the demonic succubi seduce sexually, erinyes prefer to seduce through love and virtue—and attendant sins like pride and self-righteousness and narcissism—tempting mortals with their old angelic forms. Usually, though, they prefer fighting and slaying to subterfuge. They have hated mortals since the beginning of existence: As angels they hated mortals for the love and attention the gods showed their insignificance, and as devils for not having fallen as far as they, the erinyes, have themselves.
Just after retrieving a holy artifact, an adventuring party’s arcane archer is challenged to an archery competition by an erinyes. It is a lose-lose proposition: If the archer loses, the erinyes claims the artifact from her, but if she wins, the erinyes grants her a boon which amounts to a curse in the eyes of her church (in addition to the sin of having wagered a holy item in the first place). Choosing not to play is also not an option, for the erinyes did not come alone…
A cardinal’s fiery speeches are rewarded when a trio of angels lands in rafters of the cathedral. They require him to bring priests of the faith to be judged—an order with which he complies happily, as do the priests themselves. Those found wanting—priests of pure hearts, in actuality—are hauled away in ropes made of hair or pierced with flaming arrows, while the cardinal and his flunkies are blessed and encouraged to do more to rally—and cull—the faithful.
Most angels fell eons ago, but Pithrael, the spirit of invention, fell a mere three centuries past. Since then, the progress of civilization has been slow, halting, and riddled with blind turns. If the erinyes Pithrael could be redeemed, it would mean a renaissance for man- and dwarfkind. But it could also mean that gunsmithing takes a great leap forward…and would that serve the interests of Heaven or Hell? Now many angels are as desperate as devils to see Pithrael stay fallen, while some devils are joining angels in praying for her reinstatement—creating some strange bedfellows indeed.
—Pathfinder Bestiary 75
F. Wesley Schneider’s Princesof Darkness has a bit more on erinyes. Also, caught up on the duergar and eremite entries.