Clark knows that Luthors are bad news and that you're a Luthor. That doesn't stop him from being with you, even if he does have to hide it. In all honesty, the sneaking around and hiding only makes being with you more exciting.

In class, Clark discreetly passes you notes with that stupid, beautiful smile on his face. The note says, "When are you free?"

He glances at you, hiding his smile behind his hands as he waits for you to write something and pass it back.