..... Well, im not good with advice, considering im only 12 yrs old..... but ill give it a shot.
..... You could do a character in the Malfoy family or just create a new name. make him/her (im not judgmental on homos
) Make them where they are a graduate opening up a store on Dark magic. teaching people dark magic and learning new ways to screw with people and their relationships.
....... You could do a semi-goth character that doesnt usually do anything special, and enroll them in something special such as qudditch and make them do something great that changes everyones character. Someone who would not do anything unless encouraged by a secret crush, which makes them in love and they eventually get the crush because of the great thing they did.
...... or you could make a character that is the bad type, screwing with peoples life. making them cheat on their gf/bf, then kills/injures the gf/bf. the kind of person that doesnt throw up and the blood and gore, more laughs at it. A person who would sneak around and listen in on conversations.
srry the post is long, but these are only my "bad people" ideas, lol. I didnt want you to die from reading....... it is possible....... *mischeveious look*......... *menacing laugh*