Avenger's New Teammate

Mia had been on the streets since she was eight, her parents having left her on a street corner in New York City just after Tony Stark had announced that he was Iron Man in that fateful conference, five years before the Avengers were assembled, five years before the alien attack on New York, and ten years before she tried to pick pocket Steve Rogers on the streets on New York.... What happens from there? Well you'll have to read to find out.