Protagonists are an interesting group of people. They generally have some superhuman ability and are thrown into some horrible situations. This makes me think of Post Traumatic Stress Disorder (PTSD). PTSD is an interesting thing that happens to some people but not to others. The question is, since we are talking about protagonists, why do some people not get PTSD.
When I got into a car accident a couple of years ago I was deathly afraid to drive for fear of getting into another accident. I had run into the back of another person when they had stopped suddenly. My brakes were especially squishy that day and so I was unable to stop in time. I felt like I had little control over the situation. Discussing PTSD with my supervisor we both came up with one of the factors, probably the largest part, control. If a person feels like they have control over a situation they are much less likely to have PTSD following the situation. The key word is feel. Think about soldiers who go into combat situations and are on high alert for extended time. The majority of them come home relatively okay. But me in my car crash feared driving. (I can drive just fine and it wasn’t true PTSD just an example BTW).
SO this brings us back to our Protagonist who gets shot at, thrown into dungeons, faces aliens and dragons, is raped, sees loved ones killed before them and many other horrible situations. What makes our protagonist special? Why is she/he able to withstand these situations with little to no adverse effect? One of my favorite protagonists is Frodo from Lord of The Rings. Talk about change and the effect the war had on him. In the end he was not the same, he had to leave because there was no possible way he could overcome the effects of PTSD in his world.