Prompt was the Astronomy Tower.

By the time Harry reached the top of the Astronomy Tower, it was clear that the spot was already occupied that night. Irritated, he shooed the couple away.

“You can’t make us, you’re not a prefect,” the boy complained.

Harry grinned at him. “No, but I’ve got one hot on my trail!”

The girl squeaked and grabbed her boyfriend’s arm; the pair tore down the staircase. Still chuckling, Harry settled down to wait. Severus appeared within moments, clearly amused. “That was cruel.”

Harry stood up and kissed him deeply. “Don’t care,” he murmured between kisses. “Wanted this spot for us.”