I'm not sure how this particular thought came to me. I was rewatching parts of Fast and Furious 7 recently, and came to the conclusion Tyrese's character, Roman Pierce, is my favorite character in the series. He ends up as the butt of a lot of jokes, so maybe I feel kind of bad for him, but I realized it during the scene where he objects to the mission to rescue the hacker from the fortified Death Bus convoy. He rattles off all these extremely dangerous things he's been expected to do over the last three movies, without ever having a say in it, and demands to be the one in charge of planning it, even though he has no actual plan. He really just wanted to gripe about it.
But there's also this post I see periodically on Tumblr about Max in the Mad Max movies. How guys like to hold him up as some awesome protagonist, when Max really has no interest in being the protagonist. That basically every time the central conflict of a story comes knocking, he tries to go the other direction, but can't. So maybe that was what got this going, or some combination of the two.
I strongly identify with the character who will do the stupid thing their friends need them to do, just as long as they get to complain about it. You're helping them, the least they can do is listen to you bitch about it. I think it's why I like so many of Humphrey Bogart's characters*, even though he can frequently be cruel. At the end of the day, he still does the right thing, stops the crook, helps the resistance leader escape, even if he resents the crimp it puts in his desire to make a living and drink.
I can still appreciate the characters that see an injustice and immediately step in to help, the Captain Americas and such. But I don't see much of myself in them. The characters who don't particularly want any part of the trouble, but ultimately choose to help, grudgingly, that feels familiar. It happens to me, people needing help with something, and my getting roped into it. I'm usually busy with something else, or busy relaxing, and don't want to help, but it's "the right thing to do," so off I go. Which leads to the moment in performance evaluations where my bosses praise my willingness to help when things are in a crunch, and I try not to laugh at how silly that sounds.
* It was Lauren Bacall day on Turner Classic and they were showing To Have and Have Not. Much more enjoyable than the book, even if it's a second-string Casablanca. Bacall, Bogart, and Walter Brennan carry it a long way.