When you were a baby, you were given up for adoption but your parents took you to the wrong place and you were sold at auctions across the world. Since you had been born, you had become something of an item, never had a name, never had a personality, you had never had stuff that belonged to you.
By a stroke of luck, you had ended up at an auction in Manhattan, and thankfully you were the only human on auction. When brought out on stage, you were sold for $2.1 million to Tony Stark who had recently set out on a mission to stop trafficking like this. He wanted to give you a nice home and warm food and a bed, a train you up so when you were 18 you would have a choice to either be an Avenger or he would give you a million dollars to start your own life.
The car ride back with him was quiet, Tony didn't speak much to you and when he did try to talk to you, you wouldn't speak back. When you got to the Avengers Compound, you were sat in a common room of sorts as Tony, Steve, Clint, Natasha, Pietro, Wanda, Bruce, Thor and Sam surrounded you. Bucky and some other Avengers were out on a mission but Tony hd texted them to tell them about you.
"Hey, sweetie, could you tell us your name?" Natasha asked you, putting on her motherly and calm voice, Tony, Steve, Clint, Sam, Wanda, Pietro, Thor and Bruce all hoping for a response.