My first serious Marauder-era fic. I had an idea for a prank and thought I'd see what I/they could do with it. I have about 3 more chapters to come.

Disclaimer: As the name of the website suggests this is a work of fanfiction, Harry Potter is not mine.

Familiar whispering voices fill the darkness, slowly drawing him out of a deep sleep.

"Wow, you're good at this."

"I dunno, I think that line over there needs to be a bit more curved though."

"Shut up. It's not like it's the easiest surface to work on. I'm just glad I don't have to try doing it with a quill."

He feels a faint tickling on his left arm and twitches, drifting closer to wakefulness.

"Hurry up Moony, he's going to wake soon."

"Well if you two would just keep your voices down… I'm almost done."

"I can't wait to see his face! I can't believe you actually got the idea from Lily."

"Well she did say that it was a fairly standard muggle prank, but I like our version better."

Their tone is familiar; seems like the other Marauders have decided on an internal prank this morning. Curious, Sirius yawns and sits up, looking at the friends standing beside his bed. Peter is watching him in anticipation, Remus is struggling to hide a smile while fiddling with some sort of small plastic tube, while James…

"Good morning!" Sirius looks at his best friend, raising an eyebrow at his 'I'm so innocent… not' face.

"Good morning to you too. And what are you all doing up so early?"

"Well…" Remembering the tickling feeling from earlier, he follows Peter's gaze to his left arm lying on top of the bedcovers.

What.

He feels the blood drain from his face. It is like a scene from his nightmares. His bare arm is pale against the red covers, except for a patch on his inner forearm. A matte black skull grins up at him, a shadowy snake writhing obscenely from between the jaws, twisting around itself. The Dark Mark.

"No! Get it off, get it off!" He scrabbles at it with his other hand, trying to push it away, scrape it off. It can't be the Dark Mark, he wouldn't… not ever… not even his family could make him.

"Sirius!" Arms wrap around him to hold him still; another pair of hands grab his, pulling them away from where blood is beading up from the scratches on his arm. "Calm down! It's not real. It was a joke, it's only ink. You can wash it off."

He shudders as he relaxes back into the encircling arms, panic slowly fading from his mind.

"So not funny, guys." His friends look at each other guiltily.

"Sorry. Um… I guess we should have stuck with a moustache after all…"

###

James and Remus sit on Sirius's bed carefully not looking at each other. They hear the sound of the tap running in the bathroom, and the low murmur of voices. The water turns off and there is silence for a moment before the voices start again, the tone getting increasingly frantic. The water comes on again, harder this time, and they hear vigorous scrubbing. Then, silence. Peter walks out of the bathroom.

"Um, guys… we have a problem. You know how we tested the marker to make sure the ink would wash off? Well, it's not."

Remus frowns.

"Did you try..." Peter cuts him off.

"We tried water, we tried soap, we both tried scourify. We've tried everything we can in there bar actually peeling off his skin. Sirius is freaking out again and I'd better get back to him before he decides to give that a go. If this was an extra part of the prank you didn't tell me about..."

Leaving the threat unfinished, Peter returns to the bathroom. The two boys left behind look at each other in worry and confusion.

"I didn't, did you..."

"Of course not, and we tested it..."

"What went wrong?"

"…"

"…"

"He's going to kill us if it's stuck there."

###

Unfortunately, over the next few days the boys discover the drawing is just as resistant to concealment as it is to removal. The strongest glamour charm they can find lasts barely half an hour before the lines start showing through, while more creative attempts prove to be equally useless. Even the makeup they nick from the girls to try and cover it up only dims the image, and leaves obvious residue with a tendency to rub off on clothing.

While continuing to search, Sirius resorts to more mundane methods. On the weekend he avoids his muggle t-shirts. He wears his uniform shirt sleeves down and buttoned – and hates that he now understands why such a style is fashionable – rather than rolling them up for Herbology and Potions. When washing his hands he makes sure that the bathroom is empty, and he is constantly aware of how his sleeves move to ensure his cuffs never rise high enough to reveal the dark ink beneath. He can only be thankful that his year's sorting ratio makes his friends his only roommates.

His friends are sympathetic and – after profuse apologies – help remind him when he unconsciously goes to push his sleeve out of the way, but he can't help feeling they don't understand just how serious it is.