You, Summer, are taken in with the Avengers. After you meet Natasha, it gets a bit better. But- it took some time, but during some game, you find out you're actually trapped. That's not the problem- the problem is that Natasha is trapped. On Vormir.
This is a Nat end game story through and through. I'm going make one for a Wanda as well, if you want the best of both worlds check my story swapping sides
Book 1: All Anastasia really believes about herself is that she was born to kill, that she has no place in this world. She is one of the worlds deadliest assassins, raised in the new and improved Red Room. Now 17, filled with trauma and rage. She is recruited by SHIELD after being captured, will she work with them...