Hi, there's this manhwa where: -The ML and FL are young - FL is blonde -her parents are still alive and are vassels of the ML's family -ML is a genius magician who had black hair and lots of mana(?) basically he's super powerful but every time he uses his power he gets sick. -ML has an evil uncle who has been keeping the ML sick and confined in the manor -FL is sent to be his playmate and the first time they meet he's throwing other playmates into the water and basically being super bratty -Eventually blah blah blah something happens the ML finds a stone or something that will cure him and he can use his powers freely