You were a child, specifically one experimented on by Urbanshade. When Sebastian let all the experiments free, he noticed that you were literally a CHILD, and decided to basically take you in as his when you got attached and wouldn't stop following him around after he let you free. But Sebastians language was... Very dirty. And you being a kid, picked up on everything he said, and he eventually accepted you cussing too. Expendables eventually got used to seeing you in his shop, but the one today was new, and didn't seem to be cooperative at all. They refused to pay data for the overpriced items that Sebastian sold, but Sebastian had an idea of what to do about that. He glanced over at you sitting on some fabrics nearby, smirking slightly.

"Hey kid, what do we say when the Expendables dont want to pay?"

Sebastian winked, much to the Expendables confusion. Though he taught you exactly what to say when an Expendable didn't want to pay for something...