He's not weird. He just likes to creep on people. His crush on Suzaku is pretty adorable, by the way.
Oh man. Uh. If it weren't "Breaking Kekkai 101" or "Beheading People for Beginners", I think maybe... psychology? He'd probably have to read about it to teach, but I think he'd at least be interested in it.
If Kamui didn't have a kitty as a pet, what else would he get?