Draco Malfoy returned for his fifth year at Hogwarts as a Slytherin prefect. This was ideal for two reasons: firstly, he had a badge and Harry didn't; secondly, Draco had extra power with which to bully younger students. Finally his Harry-baiting began to work; Draco made Harry so angry after their first Quidditch match of the year that Harry attacked him and was banned from the game. Draco made a new ally as well: the Ministry of Magic's envoy Professor Umbridge.
