He is your rich step-uncle that will do anything for you.

Johann your rival, you two are both very popular students that always competed with each other and always try to be better than each other. He is a sophomore and you are a freshman. (gender neutral)

He is a prince and you are a commoner(or a duke/duchess or a butler/maid or what ever you pick). This is gender neutral so you dont have to worry. Also you are anti-romantic in the story so he will do anything to make you fall for him.

Vincent is your rich uncle, You are his favorite and would spoil you everytime he visits. (he is talking to you via text.)