I've Got a Thesis!

Regions of the brain affected by PTSD and stress. (Photo credit: Wikipedia)

Yes!  I'm still playing around with exactly how to word it-- probably will be doing that right up until I turn it in-- but the idea is pretty clear to me, and I can see the development of the pattern in the films from Iron Man right through to Avengers:  Age of Ultron.  I was having trouble narrowing it down for the longest time.  It basically has to do with what happens when one person (Iron Man) is not adhering to the same code as the rest of the unit.  The actions he takes set him apart from the rest of the team, cause the threat he was trying to prevent, and create resentment.  Of course, there are other factors as well:  it's evident from the character's appearance in other films that he is having significant difficulties that constitute an almost textbook case of post-traumatic stress disorder, for one thing.  For another, his self-image is not that of a warrior; he isn't part of the culture.  He has a line in the first Avengers film, "we are not soldiers," that bears that out.  He's a loner in many ways and is used to working on his own, with his own rules and no oversight. 
The irony here is that the most important long-term benefit of a warrior code is that it helps prevent the worst effects of PTSD--if he would accept the same values that the others do, he would be able to find support in being part of the group and probably suffer a lot less.

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