River and Wraith

A pair of fox demons who serve Obscura. They were tasked with retrieving Barkley after her betrayal of Obscura. 
The party first encountered River and Wraith in Ysgard, when the pair of them tried to kidnap Barkley to take her back to the Abyss. The party fought them off, but River and Wraith said that they'd meet again. This promise was fulfilled when the party saw the pair in an inn in the Abyss, searching for Barkley still. The party avoided the couple and left town, and later found the couple in the woods along with Wisp and some Tormented Apostles. The party snuck up on them and engaged them in a very tough fight that ended with both River and Wraith being permanently destroyed. 
River fights by throwing cursed fire. The fire continues burning until a person takes their action to put it out, and friends can only put out a person's fire by using Remove Curse. Each time a person takes fire damage they gain an additional "stack" of fire, which means the fire will do more damage with each stack, on every turn. Wraith fights using charm effects, spells, and his claws. 
River and Wraith were very in love. At one point they were human, but after River was killed because his neighbors thought his bardic magic was evil, River was furious and made a deal with Obscura to kill everyone in the town in vengeance in exchange for her soul, so that she and Wraith could have an eternity together serving Obscura. Barkley learned this because after the party killed the couple for good, they left behind an orb of memories that she observed before it faded away to dust.