you were taken by HYDRA when you were a baby…you had been rescued and taken to a SHIELD headquarters, Wanda and Nat happened to be passing by to talk to Nick…they noticed you sat in a room sketching a picture. You’re currently 15 and you had no family. Wanda and Nat walked into the room and were enthralled by you…they crouched to your level and asked your name and age…you tell them and they adopt you that same day. They take you to the avengers compound and walk inside with you.

Wanda: “so Ember, this is your new home..”