this is all very boring, but it's helpful to me

"Somehow all his grief got channeled into rage that drives him through the book. Whatever happened, it is something that he can't examine too closely."

Okay, there's more to this. To be driven that strongly, I'm thinking something else has to be at issue. (Is that right? "at issue"? Anyway.) Maybe the MC blames himself for what happened to his dad.

Nah, that doesn't interest me. What interests me is having to admit that there is no way to fix what happened or bring his dad back or balance things out. No, our hero has encountered the nihilistic humanist "fact" that life has no inherent fairness or balance and sometimes there are no answers and sometimes stupid, awful things happen for petty or no particular reasons. And, that being a given, what do you do now, buddy? What you do now says who you are. Who are you, when the motivation that has driven you through all these pages is taken away?

As soon as this kid's quest is fulfilled or his question answered--or his desire for vengeance nullified--what remains is, hmm, well, the rest of his life. Maybe that's something that drives him, too. He doesn't want to face all those days without his father. As long as he's consumed with anger and his supposedly noble purpose, he doesn't have to face the very big hole that will accompany him for the rest of his life.

So, do I need to think about what happens when he faces that hole at the end of the story? Do I need to know that before I can figure out what exactly happened in the beginning? I'm not sure. Perhaps not. Will think some more.

I can tell you this, though. What happens is that he grows up.