The part about Harry Potter that always irked me is that, Harry grew up in a mentally abusive home. He was treated like crap and made to feel lower than dirt until he got his Hogwarts letter.

Implication: Harry knows, first-hand, what it's like to be alienated, ridiculed, and to have people think a certain way about him simply because of what his uncle and aunt said about him.

He goes to this brand new world, and the first thing he does is allow Hagrid, Draco Malfoy and Ron Weasley to taint his view of an entire house [Slytherin] simply because it's where "the Dark Lord was sorted" and other "evil wizards". He never even considers the fact that Sirius Black who, supposedly, betrayed his parents was in Gryffindor. Same with Peter Pettigrew after the truth comes out.

For a kid who grew up with no friends, he is perfectly content to limit himself to two friends for nearly his entire Hogwarts career. He doesn't really get to know people from other Houses until the DA was created.

But the biggest thing is, he learns first year that the guy who killed his parents is still alive and out there waiting to come back to power. What does Harry do? Complain about homework, slack off, and play Quidditch.