You got kidnapped from Hydra when you were still a Baby

You got tortured and experimented on. because you have the ability to control, manipulate and create fire out of nowhere. And You can't be burned or hurt by any kind of damage

Your 5 and were found and saved by a Avenger. who brought you in the Avenger's base

Peter: hey there little one!

he tried to touch you, but you flinch and tear up immediately

Tony: Great! Look what you did!

Steve: the kid must be extremely traumatized!