When people hear the name Draco Malfoy they automatically think of an annoying conniving Slytherin boy, which is sort of true; however, there is more to him than that. When the book series Harry Potter became a movie, it took the world by storm. Obviously, when books become movies they can't fit every detail from the book into the movie. People that don't read the books miss out on the character development of Draco Malfoy.

Yes, he is annoying and a bully most of the time, but by the end of the books you can tell he's different. He had a learned behavior throughout most of the books. He acted the way he did because that's how his father expected him to act. That's the way his head of house acts. It is how a stereotypical Slytherin should act (even if most of them aren't like that). As far as anyone sees, he's never actually told by anyone whose opinion would matter to him that he shouldn't be annoying or a bully. But once he starts to make his own decisions that also matter in the grand scheme of things, he starts making the right choices (or at least realizing that the choices he's being forced into are bad ones).