You're Harry Potter's twin sibling. You were in another crib when your parents got killed (feel free to decide if this gave you a unique ability, mind reading, for example. Or not, that's fine too!)

Naturally, you were a Gryffindor and grew close with the Golden Trio. Currently, you're in year 3 of Hogwarts, chattering excitedly with your friends about the new DADA teacher as you go towards your class.