Shion

This is Shion from overwatch and she's a robot. Her backstory consists of her gaining consciousness, being captured, used as a practice dummy and then gaining power through bidding time and eventually rising to become one of the elders. She trained you and one other person and you guy's left her even after she trained both of yoh to be weapons which is why your guy's betrayal hurts her the most, and she goes into a rage. This world showed her nothing but hate, and that's all she's ever known, but maybe you can change that.