I think you could write about his psychology, that how, even though he was subject to abuse for 11 years, it didn't affect him in the least, he was still as Humble and courageous!
There is a line that the sorting Hat says that sorta describes Harry for me, it says, "...and there is a first to prove yourself..."
You could write that because Harry didn't receive attention while growing up, he might be a bit of an attention seeker, and his way of showing this would be by acting out by breaking the rules
On the other hand you could say that Harry is so insecure as a boy because of the lack of love that by doing something right and showing courage and determination he wants to prove himself as the star that he is, and seeks approval from his elders as well as his peers!
He regards Dumbledore, both as his saving grace and as a paternal figure, so he finds it necessary to be loyal to Dumbledore because he took him out of the hell of Privit Drive, he also feels that he has to prove to others why he is famous, he has to be accepted by everyone, and would go to any length to get the approval and acceptance, even if it means breaking all the rules!
You could also write that Harry laughs off Dudleys threats to humiliate him, and doesn't take them seriously or tries to avoid them; however, when Malfoy challenges him or insults his fellow classmates (Neville for the remembrall) he feels the need to stand up for himself and his friends, he feels the need to prove Malfoy wrong, he feels at home giving and receiving threats at Hogwarts! He seems naturally inclined towards fighting Malfoy, even though he doesn't even know why he (harry) hates him (Draco)
BTW how cool is it that you get to write about Harry Potter! lol!!!