@Carnage This is just a theory, but it's probably his intellect. I mean:
1. He's pedantic.
2. He's asocial and prefers games.
2.1. He's painfully frank.
3. He always looks like he saw something he cannot unsee.
Those are signs of schizoid accentuation, which is based around high intelligence at the expense of almost everything else. How big is the expense depends on how deep accentuation is (it can go to the level of personality disorder, though it doesn't happen that often).
If you want some real-life examples of that particular eye expression, look at H. P. Lovecraft, R. R. Martin, A. Sapkowski, F.P. Herbert Jr.
My girlfriend often jokes that it's easy to find a good book if you look at the author's face, though I find it a bit oversimplifying (don't tell her, though).
Oh, and high intelligence means a good sense of humor (that's the reason sense of humor is such an important characteristic in sexual selection in humans). Also my hypothesis would explain why he's so friggin dense. Shizoids are so terrified of getting close to someone they try to find a catch in everything.