Author's Notes: Written for the 2013 HP Rarepair Cliché fest on LiveJournal. Clichés used: Polyjuice!fic, Hogwarts professors, gender!switch.

This is the most unabashed pornography and has absolutely no redeeming moral or social value. But this is why Polyjuice was invented. You know it.

A million thanks to Kelly Chambliss for the beta!

The image used for the cover is by ttstam/Flickr, used under a Creative Commons Attribution-NonCommercial-ShareAlike (CC-BY-NC-SA 2.0) licence.


A Perfectly Potent Potion

by Squibstress

Although Snape had never literally been told to go fuck himself, he was certain the exhortation had crossed the minds of many a student, and probably not a few of his colleagues.

Little did they know how very pleasant such an occupation could prove. Merlin knew he'd been surprised.

It all started, as most things did in Snape's world, with a request from Dumbledore. At some point in future, the old man told him, it would become necessary to move the Potter whelp from his aunt's meagre hearth, at which time it might be desirable to have prepared a bit of a red herring.

"A what?"

"Red herring. A misdirection. Forgive me, Severus, it's a Muggle term," the Headmaster said, ignoring in his condescension the fact that Snape, who had grown up in the Muggle world and come of age at the Dark Lord's knee, had forgotten more than Dumbledore ever knew about both Muggles and misdirection.

But when Dumbledore made his suggestion, Snape had to admit that it was clever.

So he slunk dutifully down to his dungeons to whip up a batch of what the old man required. Being a Northern boy of humble means, he could not, in good conscience, waste exorbitantly expensive and damnably perishable ingredients, so he made more of the potion than he was charged to do.

His mistress would approve, in her Caledonian frugality, and pleasing her had been on Snape's weekly to-do list for almost seven years now.

In fact, Snape thought, looking at himself in the full-length mirror, he might have found a new and surprising way to do just that. His reflection broke into a smile that would have sent him screaming for the safety of his dungeon had he not already been there. Yes, this was just the ticket. The very idea would make her squirm with Gryffindorian scruple. Then he would chide her for her lack of courage and faulty sense of adventure, which would yield the predictable results. After which he would make her squirm again, scruples discarded along with the sensible cotton knickers she insisted on wearing despite his numerous hints that black lace might place her aging arse in a more flattering light.

Still smiling, he used his wand to make some adjustments to his robes and swept out of his rooms.

~oOo~

The look of surprise and quickly hidden consternation that greeted him when she opened her door made the discomfort of the transformation worth it. Already.

"Is there an emergency?" she asked.

"No, no, my dear," he said, lifting her hand to his lips for a gallant kiss. "I just thought I'd wander over for a bit of a chat."

Her eyes narrowed. "Did you? Do come in, then."

"Thank you." Seeing the whisky and two glasses on the table by the fire, he asked, "Expecting someone?"

"A friend."

"Severus?"

"Yes, as a matter of fact."

"He's a lucky fellow, to be served your best whisky."

"Hardly my best. As you know," she said, "I reserve the best for you."

Snape almost frowned but caught himself in time and recovered well. "Do you, my dear? How delightful."

"But this is good enough for Severus. He doesn't know the difference between decent whisky and excellent whisky."

This was entirely too much.

He asked, "But surely, as a Potions master, Severus has a very discerning palate?"

"Discerning enough. For Potions."

Her insult to his gustatory abilities goaded him to act perhaps sooner than he should have.

"Whatever the man's talents, I don't think you'll be enjoying them this evening," he said.

"Oh?"

"He had other, more pressing business, I'm afraid."

"Pity," she said in a voice that suggested she found it anything but.

He took a few steps toward her and put his hands on her shoulders. It felt odd to look down at her face. She was gazing up at him without a flicker of dismay.

This would not do.

So he said, "Indeed. He thought I might be of service," and kissed her, making sure to use more tongue than she usually liked.

She pulled away, and he thought for a titillating moment that she would slap him, but she said, "You might at that," taking his wrists and guiding his hands down over her breasts.

He was so surprised that he didn't move, and she stepped away, smiling.

"On second thought, I've never been attracted to Albus. And I think it's safe to say he's never been attracted to me."

Damn.

"What gave me away?" he asked.

"Your voice. You have his timbre, but your accent and cadence aren't his. Oh, you were good, you were very good. The 'my dears' were an inspired touch. The hand-kiss was overdoing it. But do tell me, what purpose did you have for coming here Polyjuiced up?"

"How did you—"

"Know about the Polyjuice? Do try to remember, Severus, that you are not the only one Albus trusts with secrets."

She went to the table and poured out two glasses of Balvenie Fifteen-Year.

Handing one to him, she said, "My best. Albus truly has no palate for it, so this will be an experiment: Is taste primarily a physiological or a psychological phenomenon?"

He took a swallow, and the liquor burned a delicious path down his throat and into his belly. Where it continued to burn.

Double damn!

He'd forgotten about Dumbledore's ulcer.

Minerva smirked.

"So, why have you come to me this way?" she asked.

"I had to test the potion. We can't have half the Order sprouting tails or extra heads when the time comes, now can we?"

"I think your reputation as a brewer is intact. I'm less certain about your thespian abilities."

"You were fooled until I kissed you. Admit it."

"I will admit that your direct attack reinforced my suspicion. I have a healthy ego, but I'm not labouring under any delusion that my charms are enough to make a confirmed bachelor switch sides in his hundred-and-fifteenth year."

She went to a side-table, opened a drawer, and withdrew a chess board.

"What are you doing?"

She turned to him, eyebrows raised. "Since you've effectively scuttled my intention to win back last week's House points through the inventive use of various orifices—bravo, by the way—I thought I might try another tack."

"I don't see why."

She stood blinking for a few moments, and when her shoulders squared, he knew he had her. With Minerva, there was no surer aphrodisiac than debate.

She said, "Quite aside from the ethical considerations, I believe I've already told you: while I adore Albus Dumbledore in any number of no-doubt inappropriate ways, I have no desire to shag him."

"But you wouldn't be shagging Albus, you'd be shagging me."

"Using Albus's body."

"It isn't really his body. It just looks like it."

"It is morphologically the same. Polyjuice produces an exact replica."

"Aha! Replica. Last I checked, a replica wasn't the actual item."

She waved a dismissive hand. "Semantics. Although the original still exists, your body is now, cell-for-cell, the same as Albus's. In my book, that makes it his body. Just as if I made a magical copy of your last article for European Potions Review. You would surely object if I then decided to publish my copy in The Practical Potioneer."

"Of course. That paper was far too good for them. And I think you're mistaking Potions with your field. You need to get out of your ivory tower. I haven't been changed into Albus, whatever you say about cells. My mind is still my own, and so are the cells it controls."

"Are you attempting to argue Essence Theory with me, Severus? How interesting. Do they cover that now in the Cambridge certificate program in Potions? I thought it was only done at the doctoral level."

"Throwing your doctorate in my face because you're losing the debate? I'm surprised at you. Oh, wait . . . I'm not."

"This is hardly a debate, and I'm not losing. I simply don't think it's ethical for us to use an anatomically correct replica of someone else's body without his consent."

"He'll never know. Unless you tell him."

"I think you're rather missing the point."

"The point that you are missing, Minerva, is that you are turning down the opportunity for discovery. For exploration. For an excellent screw at the hands of a master."

"You're familiar with Albus's sexual technique, are you?"

"I am familiar with the fact that he has an enormous cock."

Pause.

"It's ridiculous, actually," Snape said, twisting the knife.

Her eyebrows rose several inches northward.

"I'm not sure that's information I needed," she said.

"I beg to differ. You cannot hope to make an informed decision without all the relevant facts."

"I hardly think the size of Albus's—"

"And I have some disgustingly decadent ideas about what to do with it."

By the time he left her quarters early the next morning, Slytherin was up two hundred points.

~oOo~

Despite her initial protests, Minerva proved an enthusiastic consumer of the varied delights a well-provisioned Potions master could offer her. He flattered himself that he was not unskilled in the amorous arts, but the fact that he appeared at her door each Friday night in the body of a different person lent an extra air of mystery and excitement to the proceedings, and all but ensured that he would emerge victorious when August simmered to a close and they tallied up the points from their traditional summer game.

Oh, she made noises about "totally inappropriate" when Kingsley Shacklebolt's tree-trunk-like arms bent her over the table in her sitting room, and "bordering on criminal" when Oliver Wood's young and Quidditch-agile fingers worked their magic between her legs, but in the end, she shut up, just as she had when he'd stuck Dumbledore's enormous prick in her mouth.

He should have known her competitive spirit wouldn't lie exhausted and panting for long.

She was slumped, boneless, in the large club chair, having been brought only moments before to her fifth screaming orgasm of the evening, when she said, "Next week, it's my turn."

He was using one of her ridiculous tartan-patterned handkerchiefs to wipe "his" mouth, and her words stopped him mid-swipe.

"Absolutely not. It's my potion."

He regretted selecting one of Filius Flitwick's hairs to use for the week's dose, because she stood and pulled herself up to her full sixty-nine-inch height so that he was staring directly at her naked thighs.

"Severus," she said, "our arrangement is ostensibly based on mutual pleasure and at least the appearance of collegial respect. It's my turn."

They argued for a pleasant half hour, and Minerva, clever little cat, waited until the moment he was recovering from the painful re-transformation to pounce on him with an "if you won't allow me my fair turn, you needn't bother showing up next Friday", which was typical Gryffindor pig-headedness and unfair tactics besides.

He gave her a phial.

His week-long pout lifted when he stepped into Minerva's sitting room to find that the green silk knickers he'd given her but that she, out of sheer feminine perversity, had never worn when he could see them, now encased the distinctly rounder globes of Rosmerta's arse.

When his cock was nestled snugly between bosoms he'd always suspected were fantastic, he congratulated himself on his prescience and on having been magnanimous enough to let her have the potion. Minerva's actual breasts were lovely, but too small to provide a really satisfying tit-fuck, and she took a disappointingly dim view of using Enlarging Charms on sensitive portions of her anatomy.

The following week, he gave her strapping Charlie Weasley in recompense, but she enjoyed it a little too enthusiastically, in Snape's view, so at his next turn, he showed up as Rolanda Hooch.

And promptly gave up three hundred points to Gryffindor.

Who would have guessed Minerva had a Sapphic streak?

Snape wouldn't have, but he was not about to complain; after all, he got to play with two sets of tits—both very nice—and experience the wonder of multiple orgasms.

He also got an unanticipated anatomy lesson.

"Show me how you did that," he demanded in Hooch's gravelly mezzo-soprano when they'd finished and he'd recovered the power of speech.

"Did what?"

"That thing. With your fingers."

"It's quite simple. You just . . ." She held up her damp hand, her first two digits hooked. "And press, don't pump . . ."

"I want to try it. Lie back."

"Don't bother."

He pushed her back against the pillows and prised her knees apart.

Hooch's tongue had her keening and writhing within minutes. When he judged her to be very close, he slipped Hooch's fingers inside her and did as Minerva had shown him, watching her face as he rooted around to find the right spot. She wore a patient, slightly pitying expression, and finally, he said, "Damn it, Minerva, tell me what to do."

"It's no good, Severus. I simply don't have one."

"What?"

"A so-called 'Gräfenberg Spot'. It's a—"

"I know what it is. What do you mean, 'don't have one'?"

"Not all women do. Which you'd know if you'd done your homework."

Snape was not a man to let his academic interests slide, so the following week was occupied with research, at both bench and bedside. At the end, he had to concede that she was right.

"I manage to enjoy myself quite well without one," she told him as he sat, dejected, at the edge of her bed. "You're very talented."

She took fifty points from Slytherin anyway.

~oOo~

The following week, when he got to her rooms, he balked.

"I'm surprised," she said, her accent irritatingly incongruous with her appearance. "I should have thought you'd relish the opportunity to bugger him."

Snape wasn't attracted to men in general, and not to Sirius Black in particular, but the prospect of that mangy bastard face down on the floor while Snape made him take it up the arse was pleasant to imagine.

And of course, there was the prostate. Minerva had demonstrated on numerous occasions that she was well aware of the wonders of that magical little organ, but she'd never been on the receiving end of a finger—or something larger—hitting it at just the right moment.

And he was down 150 points.

He said, "Where's the lube?"

~oOo~

His plan to clinch the victory the following week backfired when she slammed the door in his face.

He took fifty points, but the next day the rubies were back up to the previous mark. When he tried to object, she said, "Nonsense. Your tactics were against the rules, so you had no right to take points."

"Rules? What rules?" he asked, genuinely confused.

"The rules of common decency. I might have ended up in the hospital wing."

"Don't be absurd. I wouldn't have hurt you, you know." He was wounded by her implication.

"You wouldn't have intended to, I'm sure. But I don't think you're up to handling that kind of equipment."

"Well . . . that's just . . . I don't . . ."

She surprised him, saying, "It isn't meant as an insult. Tell me what you would have done had I shown up as Hagrid. Bent over with a 'carry on, man'?"

She had a point.

~oOo~

They had the same idea at the same time.

That became apparent when her door opened and he found himself staring into his own face.

It took a moment before she burst out laughing, and it was strange to hear his own bass-baritone assaulting him from the other side of the doorway.

"Do come in, Minerva," she said.

"Your accent sounds ridiculous on me," he said, stepping into her chambers.

"And you make me sound like a Sassenach," she said, wrinkling her nose.

She made a show of taking off the luridly tartan shawl he'd Transfigured from one of his mufflers.

They stood staring at one another for a moment, then they both spoke simultaneously.

"Do you want—"

"Are we or aren't we—"

Minerva smiled, and without any warning began to unbutton her trousers. She pulled out her—his—penis, which was flaccid. He was unnerved by how unimpressive the sight was.

She looked down at it.

"Sad when it's like this, isn't it?" she asked and began to stroke it, somewhat harder than he normally found comfortable.

"Be careful, woman," he said after she gave it a quick twist.

It was utterly ridiculous, but he was getting excited watching her wank his cock with his own hands.

It stood at full attention now, and he was relieved to see that it now measured up nicely from the observer's standpoint: not the freakishly large rod that hung between Dumbledore's skinny legs, but not Black's pathetic little worm, either.

He watched, mesmerised, but after a minute, it began to flag.

"Severus," she said, slightly breathless, "do close your mouth. You make me look quite stupid when it's hanging open like that, and it's a real mood killer."

He snapped his—her—jaw shut and began ripping open his Transfigured robes.

Let's see how she likes it.

When he was naked, he took a seat in his favourite armchair and spread his legs wide, running a finger from one peaked nipple—ooh, no wonder she liked that!—down his belly to his opening. Which was remarkably wet. He enjoyed a moment of smug satisfaction at being better at arousal than she was—it usually took her a few minutes to warm up enough for easy penetration—until he remembered that he was normally the one doing the warming.

Perhaps this would be instructive.

He put his index finger partway inside himself and was surprised at how little sensation it created. So he inserted another. Better, but still not the bliss he'd expected. A third finger added some pleasure, but he was beginning to understand why the prospect of Albus's Beater's bat had excited her.

She was looking at him, her hand still moving over her prick as he fingered his quim. Suddenly, she stopped.

"Why have you never told me how much this could chafe?" she asked, and Summoned a jar of lube from her bath. After applying it, she said, "Oh, that's . . . ah . . ." rubbing more quickly.

He left off his own explorations to watch her as she flogged her meat.

He couldn't help smirking. She was going to come, he could tell by the way her eyes squeezed shut and her mouth hung open.

Do I really look like that?

Her hand movements became erratic.

"Gods!" she yelled as she spurted all over her Demiguise-hair carpet.

She sagged and let out a loud sigh. When her eyes opened, shock pasted itself on her—his—face.

"Damn," she said, looking at her sticky, deflated penis.

"I think that's worth at least a hundred points from Gryffindor."

She glared at him, and the effect was delightfully disturbing.

"Fine," she said. "Since this bit of me is now effectively useless for the next few minutes, I'll have to avail myself of my charms some other way. Spread my legs."

"Yes, sir," he said, obliging.

She got to her knees, moved her face between his thighs, and sat there looking at the place between his legs as if trying to make up her mind to do it. It put him in mind of the first time they'd come together as lovers. The same considering expression had crinkled her eyes and tugged at her mouth just before she'd begun to unbutton her dress, and she'd later confessed to a momentary pang of conscience at the idea of bedding a young man who'd been her student and was, for all intents and purposes, still a virgin. Once that particular segment of her Rubicon had been crossed, however, she'd dove in with almost frightening abandon.

Which she did once again now, and showed him that while he might have moved up in the ranks from pupil to professor, she still had a few things to teach him. Her tongue licked and circled and flicked, taking him just to the edge, then backed off and probed his cunt as he came down just enough to allow her to turn her exquisite attentions to his clit again . . . and again, and again. He had no idea how much time had passed, but he was gasping and yowling and finally begging for release. When she gave it, with a long, slow lick of the flat blade of her tongue over his engorged nub, he screamed, a strangled, barley aspirated cry of visceral joy.

It was a few moments before he recovered his wits enough to recall that he'd never heard her make exactly that sound before.

"Fuck," he said, still breathing hard. "You just won back your points."

She grinned at him, a truly terrifying thing, her thin Snapian lips glistening.

To his immense satisfaction, he saw that she was hard again.

"Bedroom. Now," he said, jumping up on legs that almost didn't hold him, pulling her by the arm.

"Lie down," he said.

She did, and he climbed up between her legs and looked at his cock. It appeared alarmingly purple against the pallor of her—his—belly, but otherwise, he thought it quite nice; the length and circumference were nothing to be ashamed of, and the angle was admirable for a man who, let's face it, could take better care of himself. The fact that he was cut had embarrassed him as a young Slytherin—his House-mates' interest in other blokes' trouser snakes had bordered on the pathological—but looking at it now, his penis seemed nicely streamlined compared with the others he had recently used.

He stuck out his tongue and took an experimental lick. It was salty-sweet with come and lube, and he made a mental note to come up with a more palatable flavour for his personal lubricant.

He took a moment to ask himself if he was really going to do this, then he thought of the current House standings and of Minerva's smug smile if he failed to live up to her example.

In for a Sickle, in for a Galleon.

Holding his breath, he went down on a cock for the first time in his life. He told himself that the fact that it was his own cancelled out any homoerotic overtones to the act.

He ran his tongue repeatedly around the head, flicking at that sensitive spot just underneath each time, making it jump in his mouth. She moaned and wriggled as he sucked and licked. It was surprisingly tiring.

"Stop . . ." she gasped.

He released her cock and started to straddle her, but she said, "No. On your back."

He obliged, and she got on top of him, sinking herself deep inside his quim, and began to thrust. It felt good, but it shortly became clear that there was no way he was going to get there without some extra attention from someone's fingers or tongue.

As she pounded away, it occurred to him that perhaps he'd been a bit naïve over the years in congratulating himself on his ability to bring her off through intercourse alone.

Shit.

Had she been faking it all those times he thought she'd been coming like the Hogwarts Express?

He'd have to ask her. He had no doubt that she would tell him the truth, and he didn't look forward to the expression she'd get on her face if the answer was in the affirmative. Fuck, she'd probably been saving the information up to use against him if the end-of-summer House standings ever got too embarrassing for Gryffindor.

"This . . . is harder than . . . it looks . . ." she said, panting and pumping. In typical Minerva fashion, though, she redoubled her efforts and soon overcame whatever challenges were inherent in wielding new and unfamiliar tools, climaxing with a resonant groan and collapsing, crushing his breasts under her weight.

"Minerva," he said, "according to my last medical exam, you weigh approximately eleven stone."

"Sorry," she said, propping herself up on her elbows. She was about to say something else when he remembered one of her moves and squeezed her spent cock inside him, making her moan and shudder a few more times. He could just hear the emeralds dropping into the hourglass.

She rolled off him. "Do you need me to finish you off?"

"Of course I do," he said. "You can hardly expect me to go off like a rocket when you're so quick off the mark."

"Excuse me for being excited at having a larger primary erogenous zone than I'm used to."

"You're excused. Fingers, please."

She gave him a look that could only be described as dastardly when painted across his features.

"I have a better idea," she said.

He didn't like the sound of that. Or maybe he liked it very much, he'd have to see.

She opened the drawer of her bedside table and withdrew a large phallic object. After Summoning her wand, she tapped the phallus lightly, saying, "Vibra!" The thing began to hum and vibrate.

He frowned.

"How long have you had that?" he asked.

"This particular item, or a vibrator in general?"

"The latter."

"Since I moved into the castle. Pomona's advice, actually."

"Why do you still have it?"

"Severus, I entertain an exhausting array of foolish questions during term. I refuse to do so during what's laughingly referred to as my holiday."

"I had no idea you were so insatiable."

"I had no idea you would be so threatened by eight inches of magical plastic."

"I am not threatened, Minerva, merely curious."

"Well, then, why don't you spread your lovely legs and allow me to demonstrate."

He did, and she did, and it was fan-fucking-tastic.

Four orgasms later, he felt magnanimous, so he said, "You get two hundred points."

"Why, thank you."

"But I'm also taking away three hundred for cheating."

"You certainly will not. How is it cheating?"

"You've apparently been enjoying mind-blowing orgasms in between our trysts for seven years now, thus reducing the amount of sexual tension you experience between Fridays. I think you should consider yourself lucky I haven't deducted more points."

"And how do I know you aren't wanking merrily away every day yourself?"

He smiled. "You don't. But if I am, I'm not foolish enough to admit it."

"All right, you may have your three hundred points," she said. "But only if you agree that I can use Angus on you next Friday. As ourselves."

"Angus?"

"That's what I call it. After a particularly talented young Muggle I met at St Andrews."

"And I thought your doctorate was in Transfiguration."

"Sex was an important subspecialty. Argh!"

She began to change. The large nose melted and re-shaped itself into her slim patrician proboscis. The flat chest became nominally more convex, and the cock retreated alarmingly into the black bush, which changed remarkably little otherwise.

When it was finished, he said, "You must have taken a small dose."

"I didn't want it to last for hours in case you got the abdabs at the idea of doing yourself."

"Decent of you."

"I thought so."

He looked down at himself. "This is intriguing. And terrifying."

"What is?"

"Two Minervas."

At his leer, she said, "You must be joking. Aren't you tired?"

"Not at all. Give me Angus."

~oOo~

As he took his seat at the pre-term staff meeting, Snape was in a better humour than he had any right to be on any 1st September. Another year had passed, and the Dark Lord had not yet returned from the undead. Lupin was to be replaced by the marginally less annoying Mad-Eye Moody, and Black, although regrettably un-Kissed, was eating squirrels and pissing on trees somewhere that wasn't Hogwarts. While the Potterspawn, the Great Ginger Menace, and the Insufferable Know-It-All promised to be as irritating as ever, Snape was actually looking forward to Longbottom's first cauldron explosion and the detention opportunities that would be created by same. He'd been saving several pounds of decomposing goat bellies, courtesy of Aberforth, for just such an occasion.

Snape looked around the table at his colleagues and allowed a certain smugness to settle over him. None of them looked as if they'd enjoyed a summer remotely as pleasant as his. In fact, Sprout and Flitwick looked quite agitated as they huddled together in a buzzing tête-à-tête.

They stopped when the Headmaster entered the room, followed by his Deputy, who was all crisp efficiency and high-necked propriety. Her public primness always made Snape's dick twitch.

Dumbledore sat down at the head of the table and smiled his beatific smile. He said, "Welcome, my friends, to the beginning of a new term. I trust you all had profitable and enjoyable holidays."

That was putting it mildly.

Snape's cock hardened as he thought about the previous night.

Flitwick started to say, "Albus, I must ask why—"

The old man stopped him mid-sentence, holding up a hand and saying, "Before we begin, I should like to ask Minerva and Severus to stand."

Fuck.

Snape surreptitiously adjusted the front of his frock coat as he stood, ignoring the amused glance Minerva shot at him. She rose to stand opposite him like a green-linen-wrapped obelisk.

"Thank you. Now," said Dumbledore, steepling his long fingers and resting his hairy chin on them, "would either of you care to explain the method by which each of your Houses acquired seven hundred points prior to the start of term?"

~FIN~