Polyjuice Problems- A series of Polyjuice-induced mix-ups from different eras. First round Marauders.

Marauders Era: Missers Moony, Wormtail, Padfoot and Prongs are planning a particularly peculiar prank on the Slytherins. What happens when the joke goes bad and everything is not what it seems?

"Come on Prongs, one of us has got to test it out, at least before we go all in with it."

"So why don't you?"

"But… my hair!"

"Pads… you do realize that your hair's not getting snipped off for the experiment, right? We've already got your hair."

For a moment, Sirius Black, also known as Padfoot, was completely silent. Then he said to his best friend, James Potter, "You know, Prongs, I think we'll do it, then. Though, I may need your help rounding up a single unsuspecting little slime ball."

James's hazel eyes glittered excitedly behind his round glasses. "Shall we?" he asked, motioning out the door.

Sirius grinned and swept James a curtsey before exiting through the door that James held open.

The two other boys in the room looked at each other.

"You know, Wormy," said Remus Lupin, "It's really a wonder that they don't know why people think they're secretly gay." Peter Pettigrew burst into laughter, which James and Sirius skillfully ignored as they left.

"Secretly gay together," Sirius scoffed as the two descended the stairs, "Honestly, you share one drunk-off-your-arse kiss, and then everyone just assumes things. I've snogged loads of girls, but no, people think I'm going for you of all people. Hmph, you're not even that good looking."

James smacked him. "Oi, I'll have you know that I am the most sought after bloke in the entire school."

"Yeah, because all the girls know that I'm way out of their league." Sirius flipped his hair over his shoulder exaggeratedly.

"Either that or they know that you're secretly in love with me," James joked.

Sirius was about to retort, when he suddenly snapped into complete silence. "Prongs, d'you hear that? Sounds like an ickle snakey is slithering on through."

James grinned, "I'll be right back. You get ready with the potion." He disappeared around the corner without a sound.

Sirius measured out a small dosage of the Polyjuice potion into a small vial, and sniffed it curiously. He wondered what it would taste like before anything was put into it. It smelled fine…

Without thinking further, he took a small sip. It was absolutely awful, but he forced it down. Deciding to return to the original plan, he removed a few hairs from the pouch in his pocket and added them to the vial. The potion sizzled for a few seconds before it turned a dark red in color.

Suddenly, James was back, dragging a body. Sirius triumphantly held out the vial, and James grabbed it and dumped it down the struggling student's throat unceremoniously.

Almost instantly, the body became larger, the hair lengthened, and the kid stopped squirming.

Sirius felt very dizzy. "Pads?" he heard James say, "Padfoot, you okay?" Then everything went black.

When he woke up, Sirius was sore all over, but he still sat up quickly. Where the hell was he? He swept his eyes over everything he could see.

It looked like he was in the chamber behind the tapestry on the fourth floor. There were James and himself, as Remus was there too -wait, Sirius had seen himself? There was no mirror back here.

"Moony, Prongs, what's going on?" He croaked through his dry throat."Why am I sitting over there, and why am I tied up?"

"Merlin," Remus whispered. "He doesn't realize what's happened."

"What, in the name of Merlin's bloody left testicle, is happening?"

When James replied, his voice was tense. "What did you do before you prepared the Polyjuice?"

Oh, hell. "I may have… tried some before adding the hair…" he admitted hesitantly. "Why? What's that going to do?"

James smacked his head with his fist as Remus pulled out a pocket mirror. "Why don't you see for yourself?" he asked.

Sirius, not being one to ever pass up the opportunity to see his beautiful face, took the mirror and eagerly looked into it. What he saw staring back at him, however, was not him. Instead, the face of his younger brother Regulus, was peering back at him with a mixture of shock and revulsion plainly displayed across his features.

"I look terrible!" He cried, jerking his head up to stare in horror at his friends.

"Well," came his own voice, "I'm not too thrilled with my appearance anymore either."

"R-r-Reg? No, that doesn't make any sense. How is this even possible?" Sirius wondered aloud as his body, seemingly with his brother inside got up and started shakily pacing about the small space, which was quite a feat considering his wrists and ankles were bound.

"Well," Remus began conversationally, "It seems as if you two are going to be spending a lot of time getting to know each other before this wears off. And you might want to try and act like each other too, people might get suspicious of 'Regulus' hexing a bunch of Slytherins." He stared pointedly at 'Sirius' before catching himself and glaring towards Sirius in Regulus's body.

"Right, Padfoot, you're kind of on your own for this one, since Regulus is gonna be with us. Why don't you two try and catch up with each other and figure out how to act each other's parts, if you will. See you in a few hours!"

With that, James and Remus ducked out from under the tapestry, sealing it behind them with a muttered charm. James could be heard complaining as they left, "I guess this means no Maraudering for a while, then."

As soon as they'd been sealed in, Regulus had turned to Sirius. "This is all your fault," he said accusingly, "If you wouldn't have been fooling around with things you don't understand, we wouldn't be in this mess. Just like when we were younger, you're always dragging me into trouble."

Though it was hard to see in the gloomy darkness, Sirius scowled at his younger brother. "Me drag you into things? You went and got yourself sorted into Slytherin by yourself, thanks very much."

"And look where being in Gryffindor has got you."

"Girls, fame, popularity, renown, general likability?"

"Kicked out of the house and disinherited, you prat."

"Well," Sirius countered, "I live with the Potters now, and I'm their son. I don't need to bother with our so-called family anymore, and frankly I couldn't care less that I was disowned and thrown out on my sorry arse."

Even through the dark, Sirius could see his brows bunching together in confusion. "Don't do that- you'll give me wrinkles!" he snapped peevishly. Regulus ignored him.

"You really don't care, do you?" he asked quietly.

"I already said that I don't, didn't I?"

For a while, Regulus was silent. Then Sirius saw his own mouth open- and it really was very strange to see your own body conducting its own business without you- and he said rather brusquely, "Anyway, what are we going to do about this little issue of ours?"

Sirius threw his brother's head back and laughed, "Changing the subject, eh Reg? What's the matter, the old folks giving you a hard time? The easy pureblood life not treating you too well?"

As soon as he had started taunting, he was done. A rare, focused demeanor swept onto his (brother's) face as he continued speaking, "Though that is a good question. How are we going to get switched back?"

"I have no idea."

The two brothers sat in silence for a moment, stared through the darkness at each other, met their own eyes in the dim light, and looked away as quickly as humanly possible.

"Well, for a start, Potter and Lupin said that they were going to try to find out what was going on in the library, and see if they could find a way to reverse whatever idiot thing you did."

Sirius shrugged his brother's shoulders, "I suppose that'll have to do for now. In the meantime, what do we do in case it can't be reversed right away? Because I know it'll get suspicious if you only call Prongs and Moony by their surnames."

Regulus in Sirius's body scowled, "Then you'll have to learn to fit into Slytherin. Shouldn't be too difficult, even for you. It is where our family belongs anyway. Well, not that you'd know about belonging."

"Good luck in Gryffindor, then," Sirius snarled, "You might have difficulty with the whole bravery, loyalty, and friendship part. I don't think they actual values in Slytherin- what do you have instead? Lessons in cunning, bribery, blackmailing, and the like?- In case you were wondering, Gryffindor can kick Slytherin arse any day." Sirius couldn't help the touch of house loyalty slipping into his voice.

"Ugh, stop that, would you? You've got no clue how downright awful it looks to see someone- especially yourself- wearing Slytherin robes and misguidedly proclaiming the glories of Gryffindor," Regulus said, "It's just terrible."

Sirius smirked, but it didn't feel quite right with his brother's features, so he stopped and allowed the debate over the topic of houses slip. "So… I guess the first thing you should know about Gryffindor is that I- you, I guess, now- only really hang out with James, Remus, and Peter. But you've got to call them 'Prongs', 'Moony', and 'Wormtail'. Though, sometimes I like to find a willing little bint and have a little snog in a broom closet. Er… secondly, don't touch Moony's chocolate if you want to live."

Regulus snorted.

"I'm serious, and more so than in just name, seeing as technically my name is now currently Regulus. Which brings me to another point. Whenever someone asks anyone else in the general vicinity if they are serious, you joke that you are the only Sirius one around. Oh, and flirt with Minnie- that is, McGonagall- for me, will you? Sometimes I think she gets rather lonely with only ol' Dumbledore for company. And you know," he lowered Regulus's voice to a whisper, "I think Dumbledore's gay. So clearly, she's missing out on some love. Other than that and the usual goofing off, I think the other Marauders can help fill you in."

The Sirius Black in front of him rolled his eyes. "Okay, but wait until you hear what you've got to do in Slytherin. And take care that you don't mess anything up for me. Under punishment of death, I swear it, you had better not."

"What are you, our mother? Grating old bitch that she is, that one."

Sirius felt his own stony gray eyes bore into his forehead, "There's a very rigid system in Slytherin. I'm- you are- in the top section, because I'm Bellatrix's little cousin. I'm pretty much the second in command over everything that goes on in Slytherin house behind that fat oaf Slughorn's back. I don't care that you hate everyone in our family- you keep your mouth shut besides for anything that has to do with honoring the Dark Lord or our pureblood standards. If you screw up and they somehow find out you're not me, they're not going to hesitate to kill you, you know."

"Cheerful thought," Sirius said.

"Sorry, I forgot to mention that they'll definitely torture you first."

"Lovely. Just keeps getting all the more charming, doesn't it?"

"But if Bellatrix or Lucius or Narcissa want you to go with them to 'the usual place', don't go. Fake sick or something, anything you can do to get out of it. Trust me. You can't go there or they'll definitely know that you're not me."

"Why not? What's there?"

"I… I can't tell you," Regulus said, "I had to take an Unbreakable Vow. I'll die if I tell you, and then you'll be stuck as me until you die, which probably won't be all that long after."

"How very optimistic of you."

"Well," Regulus countered, "We can't all be merry, goblet-half-full, skipping through the field of honking daffodils, Gryffindors."

"You're going to have to try for the next few days or until whenever this is cleared up if you're going to fit in. And I suppose it'll be my turn to be the sulking, goblet-half-empty, down in the dungeons, Slytherin."

The two brothers scowled at each other from behind the other's face.

"Not that this isn't touching and all," came James's voice as Remus stepped through the tapestry. He followed, running a hand through his unruly hair, "But it's time to go now, so come with us, Sirius. And Regulus, you're on your own again."

All four boys exited the secret passageway, Sirius automatically turning to walk to Gryffindor Tower with the other Marauders, and Regulus turning the other way.

"Oi!" James turned to him and smacked his hand into Sirius's forehead, "Other way, Slytherin slime."

Sirius was stunned for a moment before James spun him around and gave him a push towards where Remus was appearing towing Sirius's body behind him. Right. "Don't touch me, you Gryffindor git," he barked at James, playing along.

James and Remus nodded at him almost unnoticeably in approval. "Later, mate," James whispered.

Sirius stalked away from them, muttering about bloodtraitor filth and thoroughly enjoying the way people stared at him in fear as he passed by giving them all a holier-than-though sneer.

Only when he reached the Slytherin common room did he realize that he had no idea how to get in. Sirius stood there dumbly for what seemed like an eternity before he felt a hand on his shoulder. He tensed and spun around.

"Jumpy, much?" his cousin Bellatrix stood there, her hand still on his shoulder. Her dark eyes glittered with mirth that Sirius had never seen there before. "I was just looking for you. I forgot to tell you earlier, the password's changed. I guess Lucius didn't find you yet either, seeing as you were just standing here like a Hufflepuff."

Sirius forced himself to crack a smile, "So what is the new password?"

"Oh, right, sorry. Here," she turned to face the wall, "Purity."

Perfect. The password practically mirrored his family's motto. He followed Bellatrix through the opening into the Slytherin common room. He flopped down onto a plump green couch, watching as his cousin settled herself into an armchair. "Reg, sit up. How many times have I got to tell you?" she said mockingly, "You'll bring dishonor to the family name slumping around like that!"

When he started to straighten up, alarmed, Bellatrix's face relaxed, and she smirked at him. "Chill out, cous', our parents aren't here." She slouched down in her own seat, still smiling, "You're still pretty easy to wind up."

Sirius stared at her, absolutely stunned. Had she gotten caught in a Polyjuice mix-up as well? With a Hufflepuff?

AN: Hey, Fiori here. Hope you enjoyed the first chapter of Polyjuice Problems. The next (two?) chapters will also be for Marauders era, before it switches over to whatever my round 2 assignment is. Please review- let me know what you think!

-Fiori ^_^