Why Should I?

Fox Summers, mutant and current Witchblade bearer, has been summoned by Nick Fury to join the Avengers. Unknown to her, she is there as a replacement for Black Widow, who is currently M.I.A. Although the guys are welcoming (to say the least), she feels there is something... Off. Why did Fury choose her? Why is Loki there? An Avengers/Witchblade mash that started in English class one day and has just kept evolving (btw it's the Witchblade anime by Top Cow I'm taking my influence from) (oh and there's some course language and sexual references in there too... :3)