How readers are introduced to a character can tell a lot about them. According to some fans of the Harry Potter books, that holds true for the characters in J.K. Rowling’s series as well.
In a recent Reddit thread, user marys524 shared their thoughts, having recently picked up the books again. “I might have noticed a pattern in the way characters introduce themselves,” they said. While the user admitted they could be “completely over-analyzing,” they shared their findings from the first installment, Harry Potter and the Sorcerer’s Stone. Your three favorite Gryffindor students fit the model to a T: Harry doesn’t introduce himself at all, he’s recognized and simply nods; Ron Weasley is introduced by his twin brothers, Fred and George, or, as OP marys524 puts it, “Even from the moment we meet Ron, his family is already doing most of the talking for him”; Hermione Granger only introduces herself after nearly a full page of dialogue, suggesting “She’s more concerned about magic (and helping Neville) and then realizes that she hasn’t introduced herself. It’s an afterthought to her.”
The same holds true for some of the series’ other characters as well.