a friend in need

A couple of times in my life I've befriended some people that, to many, wouldn't seem cool. They weren't very popular and stuck mostly to themselves. I'm not sure why I took an interest in them; maybe it's because I was tired of talking to the same people who seemed like robots churned out of a factory because they were all raised by television and pop culture. Or maybe I just wanted to interact with some people that had more trouble then me in fitting in.
Anyway, one dude in particular was very different because he was so incredibly single minded. He had one single purpose in his life and devoted every moment and ounce of strength to fulfilling that purpose. He did not care about anything else. But I knew that his reaching his goal wasn't going to be immediate so I tried being his friend because I thought he could use one. It seemed as though he didn't care one way or the other but he didn't object to my presence so I continued to be his friend and I think we became good friends for a while.
Then the day came. The day he would see his life's purpose fulfilled or die trying. It was all a vendetta; his whole purpose was to get revenge on someone who somehow destroyed his family or took them away from him. I really don't know the details.
He asked me to help him with this. I was shocked not only because he'd never asked me for anything before not even to pass the ketchup, but also because he wanted me to sacrifice for a war that wasn't even my own. It had nothing to do with me and he was expecting me to feel the same way as he.
It was a bitter moment when I had to walk away and let him face his demon alone. But I understand it because if there's only one thing in the world that a person wants, they cannot be accused of being selfish for wanting it. Or can they? I don't know.

"You don't fear what I see rather you dread to confirm what you already know and must do."