Scarlett Johansson returns as Black Widow for the upcoming sequel "Captain America: The Winter Soldier," and the actress recently spoke with Refinery 29 about the setup for her character and her relationship with Steve Rogers (Chris Evans):
"It's been two years since [the characters] appeared, and now both are agents of S.H.I.E.L.D. fighting in the streets. We are not superheroes flying side by side. They help each other because we are fighting in a similar way. It's a working relationship.
By a series of unfortunate encounters, they will be in a situation in which their friendship becomes more intimate. They share many similarities because they live on the defensive without relying on anyone.
Also, the two have been working for the government throughout their professional careers. With their friendship they begin to question what they want and what is their true identity."