Neville definitely made me realize there was more to him on page 361 of Order of the Phoenix when he heads for Draco after Draco tells Harry he's going to end up in St. Mungo's for being addeled by magic. Harry then has to pull him back so he doesn't get in trouble for fighting Draco. Regardless of the fact that it's because of what happend to his parents, it's one of the few times Neville actually stands up for himself.