One of the most dynamic aspects of the text is the characters. In the beginning of the series, we have a scared, hapless, neglected orphan protagonist named Harry Potter, reviled by his uncle and aunt for his strangeness and clearly out of place in the normal world. He soon discovers that he is a wizard and ends up at a school where he develops new friendships that functions as his replacement family. These friendships are not set in stone; indeed, there many points in the later novels where the core friendship of Ron, Hermione, and Harry almost shatters, but ultimately by the end they, too, come to realize they’re a family and need each other. There are a lot of tangible developments of Harry’s character by the end of the series:
1) One of the most obvious changes from the earlier books is Harry’s desire to play down his celebrity status; he seems embarrassed by it, wanting to blend in with the crowd, and be like any normal kid, but by the final book he embraces his role and fate as the savior of the Wizarding World, even allowing himself to be sacrificed for the sake of everyone else. His choice of name is no accident.
2) However, even more microscopic changes in his character and his relationships are evident as the series progresses; by the final book, Harry’s relationship with the Dursleys has transformed radically, with both sides expressing feelings for each other. The Dursleys, far from being merely a comical interlude and parody of bourgeoisie foibles, plays a crucial part in the development of Harry’s character. Due to past neglect and lack of parental figures, Harry struggles to trust his friends and adults at first. Ultimately, trust in others is what Potter must accept.
3) By the final book, in order to win he must trust in his friends to fight back, he must trust in Dumbledore who he learns isn’t the perfect saintly man he believed him to be during the final book; Harry might play a large part in defeating Voldemort, but he cannot defeat his forces alone.
4) In the end, Harry goes from an orphan who lost his family to building a new family through his experiences at Hogwarts and by literally starting his own as the final sequence of the novel.
5) Harry ends up facing his fears (developed and reexplored throughout the novels) and learns that death is an inevitable part of life; something, Voldemort who functions as a parallel to him, never learns or accepts. Harry learns to accept death as an inevitable part of life, which allows him to be sacrificed to save everyone else. He needs to overcome his parent’s death and his “foster” parents death: Sirius Black and Dumbledore.
Now granted from the very first books we witness a character who is brave and courageous and who cares about his friends. Rowling doesn’t change the central qualities of her character, but I do believe she develops them over the course of the books so that these innate qualities mature. He switches from others sacrificing themselves for him to him sacrificing himself for others.