Im having a hard time developing this character Help?

True wisdom comes from experience. So as for background maybe he did something bad at a younger age like 5th grade, and he learned from his mistake and it made him the mature, respectful character he is in the present. Or maybe he had an abusive family that made him never want to be like them and had him become smart. Flaws could be extracted from the past. Maybe he is prone to feeling very guilty for doing something small that is bad, so he aims to be good. Work on a past first, and flaws can come from that.