And it confuses me. Okay, like a lot of people, I have been wondering just how Harry could be so adjusted after his horrible childhood. Just for the record, I believe Harry was neglected and emotionally abused, but not physically or sexually. (I probably should but don't count Dudley's beating up Harry as abuse.) And while he may have been underfed, I don't think he was starved, either. His childhood was bad enough. We don't need to make it worse.
And yes, he can be insolent and disrespectful to authority. And when he is to his aunt and uncle, I *cheer*. He could so easily have become meek and fearful instead. But, no, he talks back to them and makes deals with them and while he obeys, he doesn't do it with grace. And why should he? They're cruel and arbitrary and clearly hate him for no good reason.
Which is the way Snape acts towards him, so why should he behave any differently? Snape clearly doesn't see Harry, he sees James. And, yes, if Harry had been raised by wizards, he might well have become James, who was arrogant and insolent and disrespectful and cruel, so it's not unreasonable for Snape to think that's what happened.
Except it didn't. He runs from publicity, until the last book when Hermione pushed him into it. He has never acted arrogant that I can tell. He sneaks around the school, yes, but I suspect so do other students. It's normal kid behavior. Snape sees all of Harry's actions through James lenses, even the most innocent.
But Snape punishes arbitrarily, at least when among Gryffindors and Slytherins. We don't know how he is with Ravenclaws and Hufflepuffs. He may be entirely fair with them because he has no emotional connection to them.
McGonagall, in contrast, is almost painfully fair, punishing her own house as much as any other, except for making Harry Seeker. Which, I grant you, is huge - but she never protested the detentions and other things that would make it impossible for Harry to play his fifth year.
And when she was hurt, Harry felt lost. She was the only person left he could completely trust. Because not only was she fair, she didn't *lie* to him. And Harry had been lied to his entire life by the Dursleys, who kept his whole being a secret, and he reacts badly to more deception by his friends and Dumbledore - people he'd trusted. It's not just that he didn't have information that he needed, it's that they kept things from him, like that he was followed. No wonder he was angry - they were acting like the Dursleys.
Other points in that essay - she uses as evidence that Snape had been abused "his multiple layers of clothing." Um. If that were the case, how come all James had to do was tip him over to show his underwear? Movie costuming doesn't really count. Not that I doubt that Snape was abused. I think there is enough evidence to see that is possible, but it's not book canon.
However it did make me think. Harry isn't reacting normally to very bad things - or he didn't until after GoF. In the first three books, he was confronted with a teacher bound to evil who tried to kill him, an evil memory who tried to kill him and, in PoA, a choice no thirteen year old should ever have to make - does the man who betrayed his parents live or die? And in none of them does he react. Someone replying to accioslash's post thought he reacted too well to them. I say he reacted very poorly. Maybe he was too young; maybe none of it seemed real. Maybe he was still so in love with the magic of his new world that he pushed it away. But the fact is, awful things happened around him, and by him, and he's not affected by them until after GoF.
And then it became real and Harry, emotionally stunted Harry, can only be angry.
I still don't see the arrogance, though.