The potions master and the head of Slytherin House. It's a well-known fact among the student body that Snape desperately wants the Defense Against the Dark Arts job and that Dumbledore refuses to give it to him. Snape has never liked any Gryffindor students and hates Harry in particular, as he still holds a grudge against Harry's father, James, for a joke James played on him when they were at school together. This means that during Potions lessons, Snape openly favors Slytherin students while tormenting Gryffindor students. Neville Longbottom is a favorite target, as Neville is afraid of Snape more than anything else. Snape tries to poison Neville's toad in their first lesson and becomes even crueler after he learns that Neville's boggart, which took his form, was forced into the clothes that Neville's grandmother wears. Harry, Ron, and Hermione fear that Snape is trying to poison Professor Lupin, as Harry sees Snape bring Lupin a smoking potion one afternoon. Harry also notices that Snape looks at Lupin with the same kind of loathing he exhibits when he looks at Harry. In the Shrieking Shack, Snape's hatred for Harry, Lupin, and James comes to the forefront: Snape screams at Hermione and refuses to listen to Lupin and Sirius Black's story, as he's too intent on capturing Black and being able to take credit for his capture as well as get revenge for his schoolboy grudge. Harry also learns that Snape is aware that Lupin is a werewolf and has been making him the Wolfsbane Potion, a relatively new and extremely complicated potion. Snape is so enraged when he discovers Black's escape that he "accidentally" lets it slip that Lupin is a werewolf, thereby forcing Lupin to resign before parents begin to insist that Dumbledore fire him.