Professor Severus Snape is a shapeshifter in Harry Potter Sorc. Stone. Everyone believes and knows him as being mean, rude, and to some, seeming to be evil. To Harry, Ron, and Hermione, they think of him in that way. They say that he was after Prof. Quirrell's job, Defence Against the Dark Arts. During the quidditch match, Ron and Hermione thought that he was the one to jinx Harry's broom as they saw him mumbling words to some spell. However, he does do good and nice things at times, 'changing personalities'. After all, he is a teacher at Hogwarts and wants to teach his students. Then, later on in the movie, it is learned that Prof. Snape was actually trying to counteract the spell from Prof. Quirrell that was jinxing the broom.