This here is a link to a Tumblr post that points out some very key points about Chuck that seem to be forgotten and overlooked in favour of judging him for being an ass!
The following was my input: I think one of the biggest missed points of Chuck is that he’s 21 years old. He’s still a kid. I can’t imagine having to deal with half the shit he deals with. Some days, I can’t even handle having to put clothes on, let alone getting up to fight a war!
And let’s not forget that people who are most likely the only friends he’s ever known are being killed more and more frequently. It’s easier to keep people at a distance if they think you’re an asshole and don’t want to get close. The more people he let’s in, the more chance he has of hurting when they die too.
Also, he’s basically been asked to give up his life. He’s very much aware that the likelihood of dying before this is over is very, very high! He’s scared! So he reacts with anger, because it’s easier to deal with that than fear.
I have a lot of Chuck feels, and really resent it when he's overlooked as being nothing more than an arrogant prat with anger issues and a bad attitude.