I think it's rather you who doesen't get Harry's character, Harry wanted to enter the tournament, he literally had a day dream about how cool it would be to become champion and win the cup.

Harry also told Ron that if he had entered his name, he would have done it at night when nobody could see him.

Ron assuming that Harry actually entered the Tournemnt was certainly not him misjudging Harry's character, if anything he overestimated Harry's abilities. He also didn't get really angry until Harry called him stupid for believing that Harry entered the tournament.

It was a pretty stupid fight in general, but it's not nearly as one sided as fanfics make it out to be.

 

I don't like Ron, but I understand why other people would. I think a lot of the Ron-haters recognize themselves in his negative character traits, and judge him for it. What do you call that? Reverse projection? Subconscious self-loathing?

To me, he's kind of like a bull in a china shop. You want a friend like that sometimes. He's got your back in a bar brawl, and he's fiercely loyal so long as you don't injure his self-esteem. He's got a sense of humor, but he's also obnoxious, lazy, and sometimes cruel. I know a few Rons in real life, and they'll never be among my closest confidants. I couldn't even fucking imagine being a girl in a relationship with a Ron. You'd be responsible for all the emotional labor, all the household labor, and for shoring up his self-worth at every turn, without any deep appreciation for the sacrifice. (Yes, yes, I know he's just a teenager, but we only have the books to go on.)

I don't think 'being an asshole' is central to his character. For me, he's the kind of friend you want in some situations, and the kind you want to keep far away in others.