An Erinyes. In ancient Greek religion and mythology, the Erinyes, also known as the Furies, were female chthonic deities of vengeance, sometimes referred to as "infernal goddesses". A formulaic oath in the Iliad invokes them as "the Erinyes, that under earth take vengeance on men, whosoever hath sworn a false oath." Kai on the other hand...is a fighter in an army of demons. Surrounded by others who have tried to throw her down, only to watch her rise up. and this...this is only part of her story.