Hermione's character develops significantly over the course of the story and sheds light on Harry's character as well. At the outset, she is an annoying perfectionist, a goody-two-shoes who has read all the books for her classes in advance, has learned all about Hogwarts, and never breaks the rules. When she first speaks to Harry on the train ride to school, she is eager to impress him with her knowledge, whereas Harry only wants to make friends. Her intellectual talents are indeed worthy of pride, as we find out later when she scores 112 percent on her final exam. But we sense that her show-off side is a defense against her feelings of inferiority, because she comes from a Muggle family and, like Harry, is unfamiliar with the wizard world. In both Hermione and Harry we see that learning wizardry requires a great deal of social adjustment and self-confidence.

Hermione's development into a likable character and a friend begins in the troll episode, when Harry and Ron are reprimanded for trying to save her from the monster and she coolly delivers a bold-faced lie to the teacher. The little girl who has been abiding by all the school rules now dares to lie to her superiors, and a new friendship is born. Hermione's decision to support her friends rather than obey the rules showcases what is perhaps truly valuable about Harry's Hogwarts experience. The school teaches him not just facts from books and how to follow procedures, but also—and perhaps more important—loyalty, compassion for others, and solidarity.