Generally speaking, James Potter liked Care of Magical Creatures. Professor Kettleburn was all right, and had any number of stories to tell about his years in Africa hunting rare magical creatures. A slightly tipsy Professor Point had sworn at last year's end-of-the-year feast that Kettleburn's stories were all "a pack of moonshine, and anyway he couldn't tell Africa from Arabia," but James wasn't too fussed about that. The stories were interesting, and Kettleburn had a dozen scars and two missing fingers to back them up. In an average lesson he'd tell a dozen action-packed tales about whatever creature they were studying that day.
Today, however, James did not like Care of Magical Creatures. It was a warm sunny day--the first they'd had in ages and almost unheard of in March--and he wanted to be outside. Instead, he and his unfortunate classmates were trapped inside; this was almost unheard of for a Kettleburn class, as the professor believed creatures were best studied in their home environment, or at least with a lot of space around them. Lessons inside usually only happened in winter. It wouldn't be so bad if they were learning about quozzels or banniks or something, but no such luck: they were studying woodworms, whose sole importance seemed to be in that they were--surprise!--made of wood. That, and their cast-off skin was a key ingredient in a large number of potions James didn't care about. So instead of appreciating the lesson, he looked longingly out of the greenhouse window and daydreamed about Quidditch. He'd managed to beat both the Seekers to the Snitch whilst scoring his tenth consecutive goal when something hit him on the head.
James blinked and looked down. A baby woodworm sat wiggling on his right arm. It coughed up a few splinters, clearly traumatized by its new and significantly bark-free surroundings.
Although he'd barely heard a word of the lecture so far, James had heard enough to be reasonably certain woodworms couldn't fly. They could, however, be thrown. His eyes narrowed. If they were sharing this class with the Slytherins, there'd be a whole host of possible culprits. But since he didn't have any enemies (at the moment) in the ranks of the Hufflepuffs, that narrowed the suspects down to…three.
James looked up. Remus, being Remus, was paying attention to the lecture. Peter was picking at a loose thread in his robes, clearly bored beyond belief. This was normal Remus and Peter behaviour, so James moved on to the final (and most likely) suspect: Sirius Black, on the other side of the classroom, apparently chatting with one of the Hufflepuff girls as though he hadn't a care in the world. And the girl in question--Jocasta Wiggs, or something like that--was looking at James and smirking.
James' eyes narrowed. Retaliation was clearly called for, but how best to do it? To kill time while he thought of a better plan, he picked up the baby woodworm (not bothering to be gentle, nothing hurt a woodworm except fire and mould) and lobbed it back towards Sirius.
It was an excellent shot; James hadn't been signed on to the house Quidditch team that year for nothing. The woodworm landed nicely on Sirius' shoulder, where it stayed, wriggling. Jocasta Wiggs covered her mouth with her hands to stifle her giggling, which had moved several notches up in pitch. Sirius, face impassive, reached a hand up and removed the woodworm, examining it critically. He didn't so much as glance at James, but his mouth twitched.
It was clear to James that the time had come for reinforcements. And since Remus was still, disgustingly, paying attention to the lesson, that left Peter. James sidled over and tapped him lightly on the shoulder.
Peter didn't look up. "You know," he said quietly, "I bet if we took one of these woodworms and fed it a tiny bit of thread from my robes, and then a little more, we could eventually teach it to eat thread instead of bark."
James paused to consider this. "What for?"
Peter looked up and grinned briefly. "Because then we could set them loose in the girls' dorm, of course."
James was tantalized briefly by the thought of the Gryffindor girls with conveniently (from his perspective) placed holes in their robes, but pushed the image out of his head; there was more urgent business at hand. "I need your help with a cunning plan."
Peter looked surprised. "What, now? Why?"
"Because anything is better than listening to this lecture. And Sirius threw a worm at me."
"Didn't anyone ever teach you that revenge is wrong?"
Peter thought about this for a moment, then shrugged. "Probably too late now. What'd you have in mind?"
Fortunately for the plotting pair, Sirius had become distracted by the various charms of Jocasta Wiggs and completely missed their hasty consultation. So a few minutes later, when Peter wandered over to them--ostensibly to ask a complicated question about the Charms homework, but really to unobtrusively dribble splinters into Sirius' hair, causing Jocasta Wiggs to nearly erupt into giggles--he was entirely unsuspecting. Peter sauntered back to his own collection of woodworms, gave James a surreptitious thumbs-up, and tried hard not to look around.
Only then did James lob a worm back at Sirius. It landed perfectly in the middle of Sirius' hair, and happily proceeded to nibble on the splinters. And just as James had hoped, it was also nibbling on a fair amount of hair in the process. He carefully aimed another worm, which soon joined its compatriot in digesting Échardes au Cheveux. Jocasta Wiggs was turning almost purple with the effort of not laughing.
It took several minutes for Sirius to notice that his hair had attracted a couple of small but ardent admirers; the real shock wasn't the two worms on his head, but the fact they'd managed to cover half his head in the woodworm equivalent of saliva. He stared at the brownish goop on his hand with a mixture of disgust and fascination for some time before turning a You will pay for this glare on James. James had a brief moment of doubt; Sirius was proud of his hair, and anyone messing it up was destined to suffer.
Still, the day he couldn't find a way to outwit (or outhex, or at least outrun) his own best friends was the day he would roll over and die, so he returned Sirius' glare with a Bring it on look of smugness.
The lesson went downhill from there, though it took Professor Kettleburn some time to notice that his classroom had been turned into a war zone. James and Sirius both recruited allies from their fellow students, and their tactics gradually escalated from lobbing woodworms to lobbing spells. Though initially the participants tried to be quiet, the noise level escalated along with the number of hexes being cast, until even the absorbed Professor Kettleburn couldn't fail to notice what was going on.
Unfortunately but predictably, when Professor Kettleburn did notice that something was amiss, it was at the worst possible moment: James threw a tickling charm that collided spectacularly with Sirius' blasting curse, and Kettleburn turned just in time to see the resulting explosion. James and Sirius were each thrown backwards from the force of the detonation, and James managed to slam his head against a desk. To add insult to injury, a box of woodworms fell off the desk and onto his face.
Dazed, pained, covered in small crawling things happily leaving brown ooze on his skin, James looked blearily up at the shadow leaning over him and said with force, "Don't think you've won, Padfoot, I'm not finished yet."
"I think you are, Mr. Potter," the shadow replied grimly, as James realized with horror that the shape of the face resembled their forty year old professor rather more than his shaggy-haired best friend. "I think the pair of you are quite finished, and about to be given detention. Again."
"Oh," James said woozily, trying to think of a good explanation for his behaviour. Perhaps luckily for him, he passed out before he could come up with anything.
"The best part was all the woodworms landing on your head," Peter said with relish, hours later as he, Remus, and Sirius were visiting James in the hospital wing. "Too perfect."
"You would like that part, Wormtail," James said bitterly. One thing Kettleburn had neglected to mention about woodworms--or perhaps James had just been too distracted to notice--was that their secretions acted as a powerful dye. His face looked as though someone had indiscriminately thrown brown paint on it, and Madam Pomfrey was still trying to find a solution.
"You're daft, Wormtail," Sirius disagreed. "The explosion was the best bit. That was classic,"
"Classic for you. You don't think the day's complete unless you've blown something or someone up," Remus pointed out dryly.
"Too true." James looked at Remus. "What about you, Moony? Everyone else is having a go at me, you might as well join in. What was your favourite part of this fiasco?"
Remus smiled. "Oh, easily, the part where you thought Professor Kettleburn was Sirius. I nearly split my sides laughing."
"I wondered about that," Peter said. "Why were you laughing so hard?"
Remus' smile grew broader. "Because it was such a good example of Potter calling the Kettleburn Black."
Échardes au Cheveux – Splinters (Mixed) With Hair, more or less, according to my husband and an online French-English dictionary.
A quozzel is a jelly-type critter who lives in caves and sets up rock avalanches to fall on anyone who invades its territory, and is blatantly stolen from Patricia Wrede's Dragon quartet. A bannik is a Russian spirit who haunts bath/steam houses, and will be helpful to you if you are polite to it and keep the bath house clean.
Yes, I wrote the whole story just for that pun in the last line.
Yes, I've been wanting an excuse to make that joke for years.
No, I have no shame.