Date: Me, Please

“I'm on time,” Harry says proudly, grinning down at his teacher.
“That's great, you know. There's some people who come in on time ever day. Imagine that.”
“No need to get all sassy on me,” Harry grumbles back. “I brought you coffee.”

or; Harry is Louis' student and obssesed with him, leaving little naughty notes on his paperwork.