Peter Hadley is a is clever and precocious boy, but as the story progresses, it becomes clear that there is something very wrong with him. Long before the gruesome finale, the story is peppered with clues suggesting that Peter is an unusual and possibly dangerous child. For one thing, Peter often speaks the way an adult might speak. This acts as a warning sign about his troubled personality early in the story and hints that something may be off. He typically calls George “Father,” rather than the more familiar “Dad” or the childish “Daddy,” which shows a coldness in him and creates distance between him and his father. This coldness also manifests in the way he effortlessly lies to his father about creating the African veldt in the nursery. When he warns George not to turn off the nursery, he does so in a breezy yet menacing way, almost like a villain in a comic book. The way he bosses his sister Wendy around is reminiscent of a Machiavellian tyrant or cult leader. 

None of these are the mannerisms of a mentally healthy child. That he and Wendy’s names allude to the main characters from Peter Pan suggests that Peter is arrogant, imaginative, disdainful of the adult figures in his life, and refusing to grow up. When Peter begins talking to the house as if it were a real person, it shows how badly damaged Peter’s psyche has become. Raised by a machine in the place of real parents, Peter “loves” the machine more than he does his mother and father. It is no wonder then that Peter chooses to protect the nursery by murdering George and Lydia, who had threatened to “kill” it.