An interviewer asked J.K. Rowling about the significance of Ginny being the seventh daughter in the Weasley family. Rowling answers, "The backstory with Ginny was, she was the first girl to arrive in the Weasley family in generations, but there's that old tradition of the seventh daughter of a seventh daughter and a seventh son of a seventh son, so that's why she's the seventh, because she is a gifted witch. I think you get hints of that, because she does some pretty impressive stuff here and there, and you'll see that again" (source). Do we see signs of how gifted a witch Ginny is supposed to be in Chamber of Secrets? Why does Rowling develop Ginny's character so slowly? How might the novels read differently if Ginny were a central character from the very beginning of the series?
When Harry tells Professor Dumbledore that Professor Lockhart's Memory Charm backfired and left him with total amnesia, Professor Dumbledore comments, "Impaled on your own sword, Gilderoy!" (18.40). Hmm. Do you think that Professor Dumbledore knows anything about Professor Lockhart's published lies before Professor Lockhart destroys his own memory? If he does know, why does he let Professor Lockhart teach at Hogwarts with a track record of Obliviating innocent people? And why let someone completely incompetent teach Defense Against the Dark Arts?
When Lucius and Mr. Weasley fight in Flourish and Blotts, the insults Lucius throws at Mr. Weasley about money and blood are the exact same things for which Draco mocks Ron at Hogwarts. How much of Draco's feud with Harry and Ron is based on his own feelings and how much arises from his father's influence? Do we get any sign at all that Draco is trying to distinguish himself from his father? How is Draco and Lucius's relationship different from Ron and Mr. Weasley's?
Chamber of Secrets was initially going to include the Half-Blood Prince in its story line. How would it have changed the whole plot arc of the novels to know more about Professor Snape's back-story in Book 2 rather than Book 6?
We get a brief glimpse of Hermione's dentist parents when she goes to London to meet Harry and Ron in Chapter 4. Mr. Weasley can barely contain his excitement over meeting real Muggles. Still, the Weasley family lives near a Muggle village (Ottery St. Catchpole). Since Muggles have an overwhelming majority in the world, how is it possible that wizards can know so little about Muggles? What preconceptions about Muggle life do you see from most wizards?
We see more of the Hufflepuffs in Book 2 than we do in Book 1, what with Justin Finch-Fletchley and Ernie MacMillan. What are the House characteristics of the Hufflepuffs? How would an account of the war versus Voldemort be different from a Hufflepuff perspective?