I'll go back to the whole "let's look at the good things fitz did in each book thing" in a sec, but let's stop for a minute and appreciate what a genius Shannon was when she created Fitz. 

Fitz comes from this really really famous family, the Vackers. Being born in such a huge family has its own pressures and expectations. Alvar cracked because of them and it's kind of surprising that Fitz didn't. Since the moment Fitz was born he was expected to be this golden boy and this really pristine character. To be a bit perfect. Although Alden and Della are great parents (and are totally rebellious if they need to be) the rest of world sort of looks up to the Vackers as "omg they are perfect" sort of thing. People either admired Fitz or absolutely hated him. 

Fitz does mention he liked being a Vacker, possibly because everything was going perfectly for him. His great grades, people loving him, etc. But obviously one thing happened because of it. His anger issues. If things don't go his way, well, he explodes. He sort of needs things to be perfect, because of the family and expectations he was born into. He still stands up for what's right, even if it means he has to break the laws, but if things don't go in his definition of right he gets really really angry. All characters have a flaw in this book, but his anger issues are something people hate so much.

This is actually why I don't ship Sophitz though. Like I said, Fitz needs things to be his definition of perfect and well not complicated. Sophie is many things but not complicated is not one of them. Sooner or later their relationship would have cracked. But that does not make Fitz a bad character at all. He's actually really interesting to read. But this is why he hated Alvar soooo much and this is why he sort of exploded when Sophie said she wasn't going to continue looking for her biological parents. It wasn't only the fact that his whole Vacker rep might get ruined, or that he might make his family a disgrace, his ENTIRE family a disgrace, but also that Sophie was not a good girlfriend, not a lot of people look at that. I'll explain that more when we get to the 8th book but still. It really really hurt him. 

Anyway, for those of you guys that hate Fitz i hope you'll reconsider after this small insight on this character.