Startale Vortigern

Startale Vortigern, original name Ceil, is a member of the Vortigern Clan, a family of assassins, and is unofficially part of the Manxome family. A mysterious girl who rarely shows her face, she acts as the Manxome's 'black-ops', being involved in missions that are much more personal to the family and its goals as compared to the normal assassination business. She is the one who murdered Vulturn's mother and Smith's wife, Claire, at the orders of the Clan matriach Estelle, making her a prime target of Smith's hidden wrath.

History
In reality, Startale is Vulturn's lost twin, who was supposed to have died in Estelle's womb in a case of 'Vanishing Twin Syndrome', but had her gasping soul/Aura consumed and maintained by the then present Vulturn.

Estelle had noticed the presence of a second consciousness inside Vulturn when he was of age 3 and had been successful to coax it out, using Startale's anger at her lost life to turn her against her mother, while also fostering in the child an emotional dependence on Estelle. It was after Vulturn withdrew into himself at age 5 when his big brother Zephyr died, did Startale take over his body and kill Claire right after she gave birth to Caroll, Vulturn's little sister.

Having seen what Startale and by extension he had done, Vulturn's mind fractured itself in an attempt to encase and then expel Startale from his body. Startale would have been killed were it not for Estelle being nearby, having anticipated these events. Just as Startale's soul was pushed out of Vulturn's body, Estelle provided her a body through the power of the Black Water, Free-Flow. A combination of sheer willpower and her powerful nature of her Aura allowed Startale to survive the exorcism, joining Estelle's side as a truly independent entity.