- you might also check Nemesis (Moirae)
Some Kindly Ones have Nemeses. They are near-duplicates who copy their sisters down to the last Title and personality trait or something in between - fiery where the original is cold and loving where the original is hateful. An entity like this is a Nemesis: a potent danger to a Fae’s immortal existence. Despite what a typical faerie would like to believe, a Nemesis isn’t an imperfect, weak counterpart, but a genuine Fae, equal in power and privilege. Educated changelings note the resemblance to their own fetches, so some believe there’s a relationship. They say the Others learned eldritch secrets from their twins and used them to craft their slaves’ stand-ins.
No matter what appearance it takes, a Nemesis has the same true name as its enemy. It’s an independent, alternate identity with its own will and desires, tied to the same foundation as its twin. If one swears a namebound oath, its obligations and benefits applies to both of them. If one loses its name, they both suffer the consequences. This doesn’t apply to Titles, however. One might have more or different Titles than the other, and Titlebound Contracts don’t transfer between them. When one of them loses a Title, the other one isn’t affected.
A True Fae’s Nemesis often fights its twin for power over their shared name. Titles offer no protection; the Nemesis has no obligation to devour them in turn before assailing her enemy’s name because it’s hername, too. This makes the Nemesis more dangerous than any other Fae the “original” might encounter. She’s just getting rid of the “extra” will. When one wins, the other’s obliterated. Most Fae don’t have Nemeses — or don’t know they have them. A Nemesis doesn’t always spring into existence when his twin’s born. They say Nemeses can erupt part of the way through an immortal’s life, born of malformed oaths or malefic rituals.
- Equinox Road, p. 88-89