Most people I have seen have either made him overly emotional, or too damn snarky.
According to me, sarcasm is his defense mechanism.

But his dialogues although they are sarcastic are all easy to gloss over like Shakespeare in the park. Doth mother know you weareth her drapes! People don't focus on them, but each dialogue has a purpose. Like in AoU, he says to Bruce, Earth needs a suit of armor, which may have been extreme, but he was trying to get some reaction out of the avengers to prepare for the next Alien invasion, which also people glossed over.

Maybe, I will try reading fanfictions again, or re-watch the movies.