Author's Note: Written for Ah, the memories by Rue-the-Marauder on the HPFC forum. The memories I used were "pulling a prank, and watching as it hits your target" and "pulling an awful prank, and then feeling bad about it."
The four Marauders sit in a circle on the floor in the common room, which is otherwise empty. They should probably be in bed, but all of them are too excited to sleep, because the Map is finished.
"It's not quite finished," says James, frowning as he traces the edge of the ink-bordered castle. "We haven't done the grounds."
Sirius shrugs. "We'll get to that when Peter finishes transforming. No going out in our Animagus forms until all of us can, remember?"
"And who's going to hold the bloody Map when we've all got paws?" Remus demands. "Or hooves," he concedes, glancing at James.
James grins wickedly. "Probably you, Moony, since you can only transform on the full moon, right? But enough arguing, let's test it!"
They bend over the Map, scanning it for people moving about the corridors. There are a few teachers – definitely not pranking them – and a few prefects – probably a bad idea as well. Sirius allows himself to match James's grin as he spots a promising name at last.
"Look here," he says, pointing to a corridor near the library. "Snivellus is wandering around past curfew. Perhaps we should remind him that he ought to be in bed like a good little snake."
Ten minutes and a good bit of scuffling later, they're all squashed together under James's Invisibility Cloak, moving carefully through the corridors. Remus and Peter are in charge of moving them along, keeping the cloak in place, and giving a warning if they spot a teacher or prefect. James and Sirius have their wands out and are conferring in heated whispers about the best way to prank Snape.
"Red and gold hair, I say," James insists. "Nothing bothers Snivellus more than looking like a Gryffindor."
"Fine, but we'll go all the way. Make his whole body red and gold – hair, skin, and robes. Hell, maybe his eyes too – is that possible?"
"Red or gold eyes?"
"Hm… gold. Red will just make him look evil, and he's evil enough already." Sirius gives a dramatic shudder.
"Stop twitching," Remus hisses. "You're going to knock us all over. This cloak isn't big enough for four people as it is."
"We'll get his nails too," Sirius puts in, imagining it with glee, "alternating red and gold, like a girl. That'll really piss him off."
"We'll have to be careful – move out of the way as soon as the hex goes off, or else he'll hit us right back. You know what his reflexes are like."
Sirius nods appreciatively and turns his attention to the corridors. They're near Snape's location now. Fingering his wand, he thinks through the incantations necessary.
"I'll take skin, eyes, and nails," he whispers to James. "You take robes and hair."
"Shut up, he's right around the corner!" Remus is the one holding the Map. He shoots a glare at James and Sirius, although it would have been more effective if they weren't cramped into the tiny space under the cloak.
They inch around the corner. Sure enough, there's Snape, sitting in the shadows of the hallway. He's reading, of all the things to be doing at one in the morning. Then again, this is Snape they're stalking. Sirius doubts if a day goes by when he doesn't find some time to read, usually books about the Dark Arts.
"Ready?" James breathes into Sirius's ear, so quietly that Sirius would bet even Remus and Peter couldn't hear it. He nods, and both of them aim their wands through a crack in the cloak provided for them by Peter.
They shout the incantations at the tops of their lungs, purposefully speaking together to make it harder to identify the individual spells. Then the four of them sprint to the side, or try to – Peter has forgotten they're supposed to move out of the way, and he trips, sending them all sprawling across the floor of the corridor. Only Remus manages to keep the cloak fully on top of him; Peter is half under it, although he's scrabbling for more, while James and Sirius are fully exposed, wands and all.
Sirius scrambles into an upright position to watch the spells hit their target. It's not as visible in the dark corridor as he would like, but Snape's hair and robes are striped with red and gold, while his face sports more of a polka-dotted pattern – one of Sirius's personal favorites. His nails and eyes aren't obvious, but Sirius knows he didn't miss.
The Slytherin has his wand out now, and approaches them with a fierce scowl. Sirius raises his wand, but a shouted, "Expelliarmus!" takes care of that and James's.
"You – dare," Snape spits out. The next words out of his mouth are a stream of curses, which proceed to go bouncing around the walls as Sirius and James duck and dive out of the way. One of them hits Sirius, and he cries out as his leg abruptly breaks in what feels like several different places. There is a scream from Peter; something must have hit the cloak as well.
The curses finally end, and Sirius sits up slowly, staring at Snape. He can see the gold eyes now, and he immediately regrets the decision to change them, because it just looks damned creepy.
"Accio James's wand! Accio Sirius's wand!" shouts Remus, who has so far gone unnoticed by Snape. The two wands fly out of Snape's grip and into Remus's. "Come on, you two." He grabs the cloak with one hand and James's arm with the other. "Let's get out of here."
"Impedimenta!" Snape screams, but Remus ducks out of the way and seizes Sirius's arm in the hand that holds the cloak.
"My leg's broken!" Sirius yells at Remus.
The werewolf twists until his wand is pointed at Sirius's leg. "Ferula!" Before Sirius can ask what the hell incantation that is, his leg is splinted and wrapped with bandages, making it possible to walk.
"Thanks – better get moving," he gasps, reaching a hand out for Peter, who grabs it instantly. The four of them tear off down the corridor, away from Snape's fury.
When they get back to the common room, Sirius releases Remus and Peter and collapses on one of the couches, wincing at the pain in his leg. "Did any of you get hit with a curse?"
"I did." Peter's voice is sulky. "He skinned my hand." He holds up the hand that Sirius hadn't been holding, and Sirius has to look away from the bloody sight.
"You two had better go to the hospital wing," says Remus, who for some reason is still holding on to James. James, for his turn, seems to be out of breath but otherwise okay.
"Right. Come on, Pete." Sirius pushes himself up off the couch and leans on Peter's shoulder as they walk out of the room again.
Later that night, lying in the hospital wing and staring at the ceiling, Sirius is unable to sleep. He can't get the expression on Snape's face out of his head. It was more than furious, it was terrifying. For the first time, it occurs to Sirius that Snape might have been more upset by the sneak attack than by the results of the hexes. Sirius recalls that time James ambushed him last year and how he nearly hexed his best friend's ears off.
He just can't get it out of his head that maybe it's not Snape who's got something wrong with him.