Someone moderately serious but can still take my silliness. Someone that can also set me straight when I'm doing something too silly. Someone that's good at snide or sarcastic remarks to help balance me out.
Someone open-minded, willing to accept most things even if they don't like it themselves. A person that has nearly as much or more trivial knowledge as me would be fun as well. So, it also means a person that definitely enjoys learning various things even if it may not be useful to them.
Oh, and it's best if they're willing to remind me of things, such as eating or going outside. But that's completely optional.
In terms of appearance... I'd like somebody small if it's female, or somebody physically taller than me if it's male. Preferably somebody with heterochromia. And if it's male, I. Would. Love. It. if he was strong enough to randomly lift me in the air and swing me around. Yeah, it's odd.
...There's something about me with loving people with nearly opposite personalities but similar interests.