Dave Karofsky couldn't help it. Even if he knew it would only make Kurt hate him, or at least resent him more, he had to touch him. Even if it was by shoving him into a locker. He needed to make Kurt notice him. He walked by him several times a day, he was cool, he knew that, he could get the girls easily, after all, he was on the football team. He knew he wasn't as cool as Finn or the other really handsome guys, but he had offers.
Not that he cared. All he wanted was for Kurt to notice him. He noticed what Kurt wore every day. He admired him so much. His bravery. His candidness. His flamboyant clothing and his singing. He loved to listen to Kurt sing. He could probably tell what mood Kurt was in by the clothes he wore by now. At the same time it was so scary, he was so visible. He was scared, every second what it would mean to be seen watching him.
In the end that's why he started shoving him. Someone would notice him watching him eventually. But who would stand up to him? Football team, huge muscles, bully. He knew he was a bully, he knew it. But he couldn't stop himself. The fear was overpowering him.
He had daydreams where he would tell Kurt he loved him. Or liked him. He daydreamed that they would eventually kiss. Or hold hands. The boldest daydream was of the two of them, walking in the hallway, holding hands, people passing before them.
He only dared dream it once, the very idea filled him with anxiety for weeks after. He couldn't help it. All he wanted was Kurt to see him. And he hated Finn. He saw how Kurt looked at Finn. It made him want to break Finns ribs. He just couldn't help it.
He passed Kurt in the hallway. They shared half a second of eye contact, and Dave threw out an elbow, slamming Kurt into the locker. He kept on walking, but the hurt look on Kurts face, stuck with him for the next hour.