A Cure For James
If you like this one, it comes with a prequel: A Lesson For James
Sirius found him in the library.
"Oi, James!" he called, "We've got quidditch practice!" He stomped his broom on the carpet in emphasis.
James hunched further over his desk. "Practice is canceled."
For a moment, Sirius stared uncomprehendingly. After the few seconds' time it took for his brain to compute and reboot, he spluttered indignantly. "W-what? You can't do that! You've been cooped up in here for days!"
His best friend assured him that, yes, he could: he was captain, and couldn't Sirius be a good little puppy-dog and inform the team?
"You're not sick are you? I mean, if Madame Pomfrey's got a warrant out for you…" Sirius pondered.
"Lovesick, maybe," Remus answered, bending down to retrieve a piece of parchment from the rat by his shoe. "What's this? 'Lily Evans is unquestionably the most amazing girl in Hogwarts. Discuss why this is so and why it would be to her advantage to be the girlfriend of James Potter in 1,000 words.'"
Peter, who had re-formed beside him, had his face screwed up in a most fascinating way.
Remus just stared blankly at James over the top of the paper.
"What inspired this?"
James flushed. "I saw her—"
"You were stalking her—" corrected Peter.
James shot him a glare. "I saw her admiring the paintings in the west gallery, and she said to her friends 'a picture's worth a thousand words,' and I can't draw for shit so… uh…"
He faulted into silence at their looks.
Sirius knew those looks to mean you are such a pure-blood. He wasn't sure if James knew this though, and it really was funny when Remus and Peter pulled him aside to explain later, so he didn't comment. Instead he gave a perfectly reasonable suggestion.
"Perhaps we should start looking for an antidote?"
"Not even Madame Pomfrey can help with this one," answered Remus. "He's stuck this way."