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?

In Gryffindor house, Regulus was having the time of his life.

Far from the strict rulings in Slytherin, he was allowed- and even encouraged to laze around and flirt and joke as he pleased. Maybe being a goody-goody-Gryffindor wasn't so bad after all.

Er… maybe he shouldn't allow himself to entertain such traitorous thoughts. Though it was nice having people immediately jump up to give you a seat by the fire rather than just having your assigned chair that no one else was allowed to sit in. It wasn't that he didn't like having his own personal seat; it was just that somehow this felt more… friendly.

He scooted farther into the comfortable couch before the fireplace. The other three Marauders were all lounging similarly, though Remus was writing an essay, Peter was staring intently at his Charms notes with a confused expression, and James was reading a book titled Transfiguration: Times and Tales.

Out of all the things he found surprising in Gryffindor was the fact that the Marauders were not, in fact, the completely foolhardy pranksters that everyone seemed to think they always were. They had some of the highest grades and spent time studying and doing homework.

Regulus wasn't sure how they managed to pull it all off- studying, planning out some scheme that would undoubtedly go off without a hitch- as all their pranks seemed to-, writing the several essays assigned each night, then turning around to sneak off to Merlin-knows-where.

As much as Regulus would have liked to let himself completely get into the whole Maraudering business, he couldn't help but think that soon enough he'd be back in Slytherin. 'Where he belonged,' added a small, irritating voice in the back of his head.

Well, until he could return to the den of snakes he'd learned to call 'home'- or as much of a home that the strict regime of the Slytherin House could possibly be- he'd just have to make do with being a Gryffindor. Somehow, Regulus wasn't all that concerned with how long it would take to switch back.

He could only wonder how his older brother was faring in the traditional House for their family. Regulus could only hope that Sirius wasn't ruining his reputation too much.

Regulus needn't have worried. Sirius was taking his role as a slimy Slytherin very seriously.

Well, as serious as Sirius could possibly be, in any case. Though he still got twinges of guilt in his stomach when he sneered at the 'Mudblood filth' in the corridors or hexed the innocent little second years for chatting too loud about Gryffindor's chances of winning the Quidditch Cup that year for the fifth year in a row.

He'd never really considered his cousin Bellatrix to be anything except for a maniacal, Dark Arts obsessed, Voldemort crazed lunatic, but it turned out that she was nothing like he'd grown up to see her as around the family. She did enjoy the Dark Arts, and Potions classes, but she liked Transfiguration almost as much as James did.

"So," she'd said to him that night as they were sitting quietly conversing in the common room, "How's your Gryffindor infiltration coming along?" The question was innocent enough among Slytherins, but she'd inconspicuously shot him a wink that had Sirius questioning the actual meaning behind her words.

"Well enough," he'd replied to her evasively, trying to get her to change the subject.

"Really?" Bellatrix had suddenly lowered her voice, leaning in towards him unconsciously, "Then how's he doing? Have you seen him lately?"

Sirius wasn't sure who 'he' was, or why she kept putting emphasis on 'his' name, but he was sure that whatever it was, he had to somehow get her to spill. After all, loyalty to Gryffindor House came first, didn't it?

He'd hesitated for a moment before treading cautiously into dangerous conversational territory, "He's fine, for now."

"For now?" Bellatrix's face had lit with an enraged spark, "What do you mean, for now? Do you really not care that he could be in danger? Merlin, Reg, I know the two of you havn't exactly been close for a long time, but really- for now? And why wouldn't you tell me about whatever this is before?"

Sirius was suddenly aware that they were talking about himself, who was supposed to be away in Gryffindor Tower at the moment rather than here in Slytherin. "I only meant that… he hasn't been doing many pranks lately. For all I know, they're plotting something big that will get him into trouble." He really hoped the Marauders weren't planning anything too grand without him- He'd kill Prongs later if they were.

"Oh." Like that, the spark had disappeared from Bellatrix's eyes. "So he… is alright, then?"

"Yeah," Sirius said softly, "He just keeps getting better."

"Good to hear." Suddenly, Bellatrix stiffened. She added in a slightly louder voice, "So what are we going to do about that dirty Mudblood who got ink on my robes?"

What? Sirius was confused.

"Bella, plotting as usual, I see," drawled a cold voice from behind him that made the hairs on the back of his neck stand up. Lucius Malfoy was standing behind him with his customary frigid sneer securely on his face. Sirius forced himself to nod his head invitingly at the older boy.

"We were just discussing the best ways to make that little shit pay," he explained, as though Lucius hadn't heard Bellatrix's comment, "Got second-rate ink on Bella's best set of robes."

Malfoy's lip curled up in disgust, "Well, I do hope you've gotten one of the little rats to burn them. I hear the contamination only spreads. Yes, the only way to assure cleanliness is to get rid of the more undesirable things once and for all." (AN: Psst- he's not just talking robes, here. Allusion to blood purity, much? And 'the little rats' are house elves. Yeah, this Lucius is pretty much the epitome of Slytherin slime, as opposed to the darling Bellatrix. You'll see where I'm going with her later, though.)

Bellatrix nodded in faux-agreement, and Sirius forced himself to do the same. "Couldn't agree more."

This seemed to appease Lucius, and he slunk off to the boys' dormitories, beckoning his cronies Crabbe and Goyle to follow behind him.

As soon as they had disappeared, Bellatrix gave an uneasy sigh, "Honestly, I don't know what Narcissa sees in him."

Sirius could only shrug. He had no idea what drew his cousin to Lucius Malfoy's side, but it seemed that any time he saw Narcissa, she was clutched tightly in Malfoy's arms.

"Just watch," Bellatrix continued, "Right after we graduate, they'll be getting married. And I'll probably have to be the Maid of Honor, or our mum will disown me. Oh, shit, sorry Reg!"

Apparently, Sirius had failed at trying to hide the muted pain that still flashed across his face when there was talk of anyone being disowned or kicked out of their family. "S'okay," he muttered, "I know you didn't mean anything by it."

"Still," she said, "I want to make it up to you." Her face stretched with a smile, the same wild, devil-may-care, smile that Sirius had grown up seeing from her. "How's you and me going to Hogsmeade tonight, then? Havn't done that in a while, now, have we?"

"No," Sirius supposed they hadn't. At least, he and Bellatrix had never gone to Hogsmeade together before, "So, when should we-"

He was cut off by the arrival of a third year girl clutching a scroll with a green ribbon around it. "Bellatrix Black!" she squeaked, thrusting the parchment towards them. His cousin took the scroll and opened it with a roll of her eyes.

"Slughorn," she said, "Hmm, wonder why he wants to see me. Well, I'd better get going, then, but I'll meet you at the Trophy Room at… 10?"

Sirius nodded. He knew he probably shouldn't trust Bellatrix, after all, she was a Slytherin- but then again, so was he, for the moment. His older cousin ruffled his hair as she left for the Potions room, and he smiled at her back as she disappeared.

He slumped back down, closing his eyes for a moment and trying to figure out why he'd never before been able to see this side of Regulus's life, or the Slytherin life, for that matter.

"Oh Reg," a hand smoothed his hair down. Sirius opened his eyes again. Narcissa was perched on the armrest of his seat, looking at him disapprovingly, "Would it kill you to comb your hair? I know you're not as vain as your darling brother, but really. Aunt Walburga would be ashamed." (AN: Walburga is Sirius and Regulus' mother, according to JKR)

Sirius scowled at her, purposely shaking his head to muss his hair again. Narcissa just laughed at him.

"Do you know where Bellatrix went?" she asked, "Because I needed to talk to her."

"She went to see Slughorn for something," he told her, "Why, what did you need?"

Narcissa positively beamed, "Just some good news. Our mother sent me a letter, see. So, I have to let her know what's going on. I would tell you, but mum wants me to tell her first, and besides, it involves her too, a bit."

Sirius raised an eyebrow. "I see." This was just like Narcissa- getting someone's curiosity up, and then withholding information to sate the curiosity. It was ridiculous tactics like these that would most likely cause her to be a popular socialite in the future.

Lucius reappeared at her elbow, grasping her hand and pulling it to his lips. "Narcissa, darling, I take it you have not yet found your sister?"

Sirius held back a disgusted grimace. "Well then, shall we all go to find her? She shouldn't be too far- she was only going to Slughorn's classroom."

Lucius regarded him coldly, then motioned for Sirius to follow along as he swept, arm in arm with Narcissa, out the door. For a seventeen year old, Sirius thought, Lucius certainly was quite the bigoted fun-sucker.

The strange party of three found Bellatrix returning from her meeting with Slughorn, a letter clutched tightly in her hand and a huge smile on her face. The smile slipped slightly as her sister detangled herself from her beaux and ran to embrace her, handing her a letter sealed with the Black family crest.

When they pulled back from each other, Narcissa gasped out, "Guess what, Bella! Mum sent me a letter, and they've arranged with the Malfoys that Lucius and I are going to be married in the fall- which is cutting it a bit close, with having to plan everything out for the wedding, but I can't wait- but aren't you excited, Bella? Mind you, you're going to be my Maid of Honor, right?"

Bellatrix embraced her sister again, "Of course, I'd love to Cissy." Sirius could only imagine the look on her face, as it was currently buried in her sister's shoulder, "That's great news." He was pretty sure that he was the only one who heard the flat tone of Bellatrix's voice, even through her praise of her sister's situation.

"Well," Sirius interrupted, "I suppose Bellatrix and I will just have to leave you alone to celebrate and go announce the news to everyone else." He refrained from adding, as Narcissa will most certainly want to rub it in that she's marrying the handsome, rich Lucius Malfoy, and instead smiled innocently.

As soon as the happy couple had retreated back to the Slytherin domain, Sirius turned to Bellatrix. His older cousin's face had fallen considerably as she stared apprehensively at the letter in her hand. "So," he hedged awkwardly, "What did Sluggy want?"

"He informed me that the International Transfiguration Studies Corporation would be most interested in having me join them as soon as I graduate." That had apparently been a dream of Bellatrix's, to join the most renowned Transfiguration league in the Wizarding World. However, to Sirius's confusion, her voice remained flat and emotionless.

Slowly, and with trembling fingers, Bellatrix opened the letter from her mother. Her eyes widened as they raced back and forth, drinking in the information on the single page of parchment. As she neared the bottom of the letter, her eyes darkened and narrowed before shutting entirely.

Sirius slowly approached his cousin, "Bells? You alright?"

"Yeah," she said slowly, "I'm more than alright. I'm engaged." She gave a harsh laugh, "Apparently I'm to be wed to Rodolphus Lestrange within a month of graduation. I guess I'm not going to be joining in with Transfiguration Studies now. Instead, I'll be expected to be little more than a glorified house elf."

"Bellatrix, you don't have to do anything you don't want to, you do know that, right?"

"Reg, I do have to. I'm too far into things to get out now. And I can't end up like Sirius and Andromeda- I'm not like them, Regulus, you know that. I could never stand to be disowned from my family, my Slytherin family. It's all I've ever known." She swiped at her eyes quickly, so fast that Sirius couldn't even be sure that she had done so.

"Just promise me one thing. Never, ever let yourself make the same stupid mistakes that I have. Please."

Before Sirius could respond, Bellatrix had rocked back onto her heels and hurried away. "Go to bed, Reg," she called over her shoulder, seeming more choked up than when a fourth year had accidentally spilt salt over her dinner without her notice.

He just stood in the hallway, utterly stunned. I guess we won't be going to Hogsmeade, then.

Regulus was sitting with the Marauders in the sixth year's dormitory room. It was the night of the full moon, and the other three boys were steadily growing more antsy by the minute. "Would you idiots relax?" He yelled out finally, "I know he's a werewolf, so stop fidgeting."

Peter fell off the end of his bed. Remus looked shocked. James had the grace to simply cock an eyebrow in confusion.

"Damnit! Does everyone know?" Remus's hands flew to his head and grabbed fistfuls of his prematurely graying hair. "First you three- well, Sirius, James and Peter-, then Snape, then Lily, and now you!"

Regulus swallowed, and looked at his feet. If only he could explain to them that someone other than himself wouldn't have been able to figure it out, that the only reason that he knew was from seeing Fenrir Greyback at the Death Eaters meetings as they grew progressively closer to the full moons.

"I did some… studying on the topic recently. It's not that obvious, you know, so stop worrying so much. It's no wonder that you're looking older already." He couldn't help but reassure the other boys.

James looked like he was considering something, and then after a few seconds of utter silence, he turned toward Remus halfway, "Moony, we should see if he could…"

"You sure?"

"You know how to perform an Unbreakable Vow?" At Remus's nod, James got to his feet and approached Regulus. "We might let you in on a little Marauder secret, that is, if you wouldn't mind," he motioned to Remus, who was holding his wand at the ready, "allowing us to take the necessary precautions."

When Regulus shrugged, he smirked, "Good. Now, envision yourself as Sirius, becoming something inside of himself. It might help to close your eyes."

Regulus wasn't sure if they were trying to play some sort of cruel joke on him, but he shut his eyes anyway. This is stupid, he thought, what's going to happen? No, okay, got to think Sirius-ly. Haha seriously, Sirius-ly. Wow, did I really just think that? This whole acting-like-Sirius must really be rubbing off on me.

"Pad- Regulus, open your eyes." James was still standing in front of him, but his head was slightly lower than it had been. Regulus caught sight of himself in the mirror over one of the chests in the room. He was now a large dog roughly the size of a small horse. What the-

"Just a little something we Marauders happen to do about every month or so," James said casually, as if having a huge monstrous dog in the room was an everyday occurrence for them. Though, after this, Regulus wouldn't be surprised at all if it was something that Sirius did every day just for the hell of it.

"Now, for the Vow…"

AN: Thanks for reading the second installment of Polyjuice Problems: Round One (Marauders Era)! A special thanks to Cutieness (only I wish you were signed in so I could reply to your review instead of needing to delay my thanks until now) and DanceThroughMyStory for reviewing! (And don't worry, there's no James/Sirius. [And sorry to the slash fans] This isn't really a romance fic, so there really are no true 'pairings.' And plus, I'm trying to keep it as realistic as I can, well, at least, at the ending it will all be Cannon.) Anyway, please let me know what you thought of this chapter, and check in for the next (and probably final) chapter of Round One (which should be up before, or at least by, Friday)!

-Fiori ^_^

(And sorry for the long author's note here!)