Draco waited until he couldn't stand it anymore. Then he lured Harry into an empty classroom and pushed him up against the wall.
Harry struggled briefly, then he put his arms around Draco and kissed him like he couldn't stand it anymore either.
"Wait," said Draco, when they were done. He pulled silver strands out of both their heads, dropping them into a small stone basin.
Then they glared at each other, bristling.
"What do you want, Malfoy?" Harry said.
"You're the one following me." Draco picked up the Pensieve and left.
Draco waited until he couldn't stand it anymore.