Dumbledore's Army
Harry has a vision involving an attack upon Arthur Weasley, from the point of view of Arthur's attacker. Concerned that Voldemort will exploit this connection to Harry, Dumbledore instructs Severus Snape to give Harry Occlumency lessons to defend his mind from Voldemort's influence. The connection between Harry and Voldemort leads Harry to further isolate himself from his friends. Meanwhile, Bellatrix Lestrange, Sirius' deranged Death Eater cousin, escapes from Azkaban along with nine other Death Eaters. At Hogwarts, Umbridge and her Inquisitorial Squad expose Dumbledore's Army. Dumbledore escapes as Fudge orders his arrest. Umbridge becomes the new Headmistress. Harry's relationship with Cho falls apart, as he believes she betrayed Dumbledore's Army to Umbridge. Harry discovers through Snape's memories why Snape hated Harry's father James, who often ridiculed him.