Hela was born ages ago to the being who would one day be called Odin and a goddess whose name and image have been lost in antiquity. On the day of her maturity, Odin appointed her goddess and ruler of the northernmost realms of the dead. Her special dominion was over the souls of all who did not die in battle, while Odin himself built the palace Valhalla to house the souls of all of those who died as heroes. In recent years, when Odin’s attention had strayed from the maintenance of Valhalla, Hela tried to annex that realm to her own, hoping to consolidate her power over all Asgard’s dead. Eventually Odin grew aware of her ambitions and opposed them. In the course of battle, Odin’s band of Valkyries, the custodians of Valhalla, lost their physical forms, no longer able to travel from Valhalla except in their wraith-like astral forms. Hela gave up her contest for Valhalla when Odin vowed to keep better watch over it in future, and she returned to her realms.
AND she's related to Elvira.