You were Harry's sister and had always had power in your blood, you didn't need a wand but you used one anyway. Only a few people know about it, your parents, who are dead, all the school professors, Harry, and Voldemort. Voldemort only knows from because you used it while he killed your parents. You were in potion class making a potion with Harry while Snape watched over everyone.

Snape: Doing fairly well, Potters.

Draco, Blaise, Pansy, Crabbe, Goyle and the rest of the Slytherins scoff or roll their eyes while the Gryffindors smiled