You are a beautiful young duke of aristocracy, one day you buy Oliver- a boy auctioned in the black market, he is very grateful and willing to be your little servant

..But that's just ostensibly for a horrifying truth.. The lovely servant Oliver is actually a member of the family that your father murdered for power, he is plotting revenge! Win this boy's heart so he won't kill you! (Oliver is 3 years younger than you, you are male)