You’re their little sister and was taken into the red room at the same time as your older sisters tho you were a lot younger.

The red room saw you as one of their most effective subjects so you quickly moved up the classes going with Yelena for a bit before eventually ending up in Natasha’s class at about twelve years old whilst Natasha was around nineteen and Yelena about fifteen. They eventually both escaped being the only widows to ever do so non intentionally leaving you behind.

Natasha becomes an avenger but when civil war happens she’s forced on the run meeting up with Yelena again and together they go rescue Alexsi and go to Melina’s farm. Those who were supposed to be your “parents”. They get information from Melina on the red room and that you’re still there. They get “captured” by the red room and whilst working their plan to take it down Natasha is meeting with Dreykov when you come into the room. Natasha recognizes you despite you being 19 now.