What are some reasons I think about this guy?

This one guy, let’s call C, has confused me about my feelings for him. I seem to only think about him at school which is strange because I don’t at home.

What I can’t figure out is why I think/obsess about him ONLY at school. I don’t like anything about him, and for some reason we both ignore eachother but even though that, I still can’t get him out of my mind when I see him. When I mean he is in my mind, I mean I notice where he’s at when he’s far away frequently but when I’m close up to him I can’t make eye contact or look at him unless he speaks to me.

I am looking for reasons on why this may be, even though I am the one asking and I am the one that knows him and me best, I do not seem to know and am confused as I don’t have much experience with “crushes”