Harry Potter and the Prisoner of Azkaban attacked by a big black dog, which Harry has seen several times before. The dog drags Ron through a tunnel under the Whomping Willow into the Shrieking Shack. Harry and Hermione follow, and there is a brief standoff when they find Ron with Sirius Black, who has transformed from the dog. Lupin enters, and they explain the situation to Harry and his friends: Lupin is a werewolf, which led to his friends James Potter, Sirius Black, and Peter Pettigrew becoming animagi. Lupin explains that Scabbers is Pettigrew in his animal form; he has been hiding from Black, whom he had
Harry Potter and the Chamber of Secrets seven books had been published, Graeme Davis regarded "Harry Potter and the Chamber of Secrets" as the weakest of the series, and agreed that the plot structure is much the same as in "Harry Potter and the Philosopher's Stone". He described Fawkes's appearance to arm Harry and then to heal him as a "deus ex machina": he said that the book does not explain how Fawkes knew where to find Harry; and Fawkes's timing had to be very precise, as arriving earlier would probably have prevented the battle with the basilisk, while arriving later would have been fatal to Harry