He's sitting across from you, his eyes flying back and forth between the paper and your side profile, the pen in his hand swiftly flying over the paper. He doesn't even realize what he's doing, he's so absentminde, not caring about class at all, and just... drawing you apparently. Totally not because he likes you, no, quite the opposite, you two constantly bicker and banter, you are just... sitting in his vision, that's all.

And there you are, not looking, not caring, not noticing anything, you're solely focused on the professor talking.