There wasnt a lot of deduction work required on this one. Natasha Romanoff, a.k.a. The Black Widow, has always been a mystery since her introduction in Iron Man 2. Although she proved herself a capable agent in Iron Man 2, we didnt get information regarding her personal life. The Avengers shed a little light by revealing that she had red in her ledger from her actions as a Russian spy. When S.H.I.E.L.D. sent agent Clint Barton (Hawkeye) to eliminate her, he instead saw her potential and recommended her for recruitment. Leaving her old life behind, she became one of S.H.I.E.L.D.s most talented agents. Producer Kevin Feige revealed that Avengers: Age of Ultron would delve more into Natashas backstory, and Scarlett Johansson later added that wed learn how she became the person we see. There have also been rumours about Black Widow getting a solo film at some point. Regardless, whether its in her own movie or as a supporting character in another film, eventually Black Widows past will be spotlighted. It might be years before we learn the full story, but I think it will be worth the wait.