ok, again thanks for all the suggestions. Read through them. I'm looking for something mystical. There are different types of wiccans from what I've been told. I think I'm going to go with my original idea with a twist from the suggestions.
I thought of that but thinking it through with the suggestions- She has a series of crimes, all alluded to the heroes in their previous adventures. The heist that gets the players involved is of a visiting display at a museum. In an interview the curator, who is familiar with Greek mythology, says the video tape caught a mysterious women just appearing then disappearing like a "modern day Hecate." The media runs with this quote. The anti-hero of course does not call herself this thinking herself more of the Grey Witch(not completely sold on this name), who is an actual follower of Danu. Hecate, the goddess, gets mad for the use of her name and sends the Erinyes (Furies) to punish the Grey Witch. The Erinyes arrive at a time the players, one who has connections to Celtic mythology himself, has tracked down the Grey Witch/Hecate either at another heist or at her lair. What does do the players do? If they chooses to save her from the Erinyes then a possible romance could occur with one of the players. And how does she and the payer convince the goddess Hecate she didn't intentionally steal her name. If they don't Hecate(the Goddess is pleased) but Danu could get mad. Throw in the Empusae as well as the true purpose of the artifact she stole from the museum for a patron and it should give several session worth of entertainment.
Thanks everyone for the suggestions. It helped to make a more entertaining story for the campaign!