Kyon from The Melancholy of Suzumiya Haruhi
Kyon is the personification of 'be careful of what you wish for.'
He wanted to be a part of something larger. He wanted to believe in aliens, espers, and time travelers. He wanted the world to be more than what it was. So, naturally, Suzumiya Haruhi took an interest in him and, from what he tells us, ruined his life.
I think my favorite thing about Kyon is how much he tries to show that he has complete apathy. He wants others to believe that he wants nothing to do with Haruhi, despite how much he tried to initially get involved with her, how much he actually does for the SOS Brigade, and how violent his objections to her reality are.
I mean, look how hard he is trying here:
He lets himself get swept up in Haruhi's pace and enjoys it. He's sarcastic as hell as a means to not get caught up in her world but at the end of the day, doesn't really care. He's wonderfully relatable and never ceases to amuse.