A/N: At last! It's Snape vs. the Guru in the Potions Lab!

Disclaimer: nope, still no ownership, no profits, no nuthin. Bummer.

What the hell is going on out here? - Vince Lombardi

Harry Potter and the Cliché of Death Chapter 3

Severus Snape, Potions Master and Professor at Hogwarts School of Witchcraft and Wizardry swept into the Potions dungeon with his trademark swirl of robes. Scowling out across the wretched Gryffindors that insisted upon soiling his Slytherins with their very existence, he drew a deep breath in preparation for launching into his customary beginning of class tirade.

Unfortunately for the Potions Master, he was still inhaling when he noticed the newest addition to his classroom. The choking which followed required several moments, as well as a conjured glass of water, to bring under control.

"And just what do you think you're doing in my Potions classroom?" Snape finally managed to choke out.

The Guru smiled at the Professor, appearing to not have a care in the world. "Oh, I just thought I'd come down here for a bit of slumming…you know, see how the other half lives, give you a few pointers, that kind of thing. Might even teach the kiddies a thing or two along the way, you never know…" he finished cheerfully.

"Wha…give me a few pointers? Why, you…" Snape sputtered as his coughing fit resumed.

"You know, you really need to see somebody about that cough. I could whip you something up for it, if you'd like," the Guru said happily.

The Potions Master looked as if he was going to have a fit of extreme apoplexy at this last, which wasn't improved when the Guru moved to slap him vigorously on the back. "That's it, just try and breathe. Give me two minutes, no, I don't mind at all…fix you right up!" Somehow Snape found himself guided to a seat off to one side of the desks, while the Guru turned towards the door.

"Front!" he called, and immediately the same three house elves which had come at his call before appeared with quiet pops. "Hi, boys…up for running a little errand for me?" he asked, smiling as the elves nodded vigorously. "Good, good…now, I'll need a bottle of medium-good whiskey, a bag of hard peppermint candy—or a cup of sugar, if you can't get the peppermints—an ounce of oil of peppermint, a funnel, two shot glasses and a can of Coke®. Can you get that for me?"

"Master Doctor Guru, sir, will firewhiskey do?" the boldest of the elves asked, while the other two looked at one another uncertainly.

"I don't see why not," the strange man answered, smiling warmly at the little creatures. "Just as long as you don't bring me a bottle of the very good stuff…it's a crime against nature to turn really good whiskey into cough syrup."

"We is being right back!" the elf squeaked, nodding happily, and all three disappeared.

Smiling, the Guru turned to face the somewhat stunned class. One quick glance at Snape convinced him that the Professor wasn't in imminent danger of asphyxiation, so he promptly directed his attention to the students.

"Well, it seems that I'll be starting off with a simple recipe for homemade cough syrup," he said, pitching his voice to carry to the back of the room. "Now…who wants to volunteer to help me throw this together?" Looking around, he noticed that most of the students were busily averting their eyes, desperately trying not to be chosen. Well, then, time for a little fun. "Neville Longbottom, front and center…where's Neville?" the Guru called out.

"Huh…here, sir," an anxious voice came from somewhere in the middle of the room.

"Well, Mr. Longbottom, get your bottom up here," the Guru laughed, waving the trembling boy forward. Ignoring the young wizard's stammering attempts to tell the older man about his dismal skill in potions, the Guru merely patted him on the back and smiled down at him. "Buck up, old man. You'll do fine. Piece of cake." And then he winked at the young man, his eyes twinkling.

Just then one of the house elves reappeared, holding a fifth of McTavish's Pride White Label firewhiskey. "Is this being good enough, sir?" the elf asked anxiously.

"Honestly, I don't know…let's find out, shall we? Did you bring the glasses?" the Doctor asked, nodding his head when the elf produced the requested glassware. "Very good…now, let's see what we've got here," he said, deftly opening the bottle and pouring a generous amount into one of the shot glasses.

"Tookers," he toasted the class, then threw the entire shot back in one smooth motion.

For a long second nothing happened. Then, the Guru's eyes crossed, his face twisted into a strained grimace, his tongue protruded from between his lips and his head began to vibrate rapidly while a 'latalatalatalatalat' sound came from somewhere around his mouth. Then, his head locked into place just as a piercing steam whistle sound filled the room while flames and smoke shot out of the fat man's ears.

"Smooth," he gasped out, then coughed once, pounded himself in the chest and coughed again. "Oh, yeah!" he said in a nearly normal voice. Then, straightening, he exclaimed "that'll tickle the innards! Oh, my, yes, that'll do nicely, thank you," he grinned down at the happy elf. "Now, about the other things I asked for…?"

Just then a second elf popped in. "We is not finding pure oil of peppermint in the kitchen, sir, so Welky is popping out to get some. I is finding this bag of peppermint candies…will that do the Master until Welky returns?"

"That will do nicely, in point of fact. Oh, I will need a clean dishcloth and a rolling pin…or maybe a claw hammer, if you've got one handy, since we're going to use the peppermint." The Guru's broad smile became a bit accusing. "You didn't happen to find these candies in the Headmaster's office, by any chance…did you?"

The little elf blushed and stared at the floor for a moment before looking up, grinning. "Maybe?" he said, then popped away smiling when the Doctor laughed out loud. In seconds he was back with the requested cloth and rolling pin. "Mikkey is wanting to know what Master Doctor Guru is using the cloth and rolling pin for…if Mikkey is being allowed to ask," the elf said quickly.

"Of course you're allowed to ask," the Guru said, taking the cloth and rolling pin. "It's quite simple, really…I'm going to use this to crush the peppermints, because it makes them easier to mix in the firewhiskey."

"Sir, you're going to…mix candy in firewhiskey? Isn't that dangerous?" one of the Slytherins asked carefully.

The Doctor grinned. "I have no earthly idea…I suppose we'll just have to do the experiment and find out, now won't we?" Seemingly unconcerned about the possibility of something going wrong, he proceeded to pour the peppermints into the center of the cloth, which he then gathered up and twisted closed.

"All right, Mr. Longbottom, time to get to work," he said, handing the cloth to Neville. "What I want you to do is pretend that this cloth is Snape's greasy head, and give it about two dozen good whacks with this rolling pin. Think you can do that?" he asked, ignoring the fresh sputtering coming from the direction of the glaring Potions Master.

"With pleasure, sir," Neville replied, and set to his task with a will. For the next minute or so, the sound of Neville pounding the candies into power—paused only briefly when the Guru showed him how to hold the towel closed properly, and reminded him not to smack his own hand—echoed throughout the dungeons.

"Well, that should be good enough," the Guru said, when a madly grinning Neville paused to take a breath and shake out his arm. "Oh, yeah, that's just fine, Neville. Now, where's the whiskey and the funnel?" he asked looking around. Taking the bottle, the Doctor poured himself another generous dose, which was tossed back with considerably less drama than the first one. In fact, all he did was smack his lips and exclaim "ah, Mother's milk!" before using the funnel to pour a quantity of crushed candies into the flask.

"Now, Neville, while I'm shaking this to dissolve the candy, why don't you tell the class what you know about the peppermint plant?" the Guru asked gently.

"I…uh…sir?" Neville asked, suddenly anxious.

"Oh, come on, Neville, it's hardly a secret that you're the hottest thing to happen to Herbology since cow manure," the Guru scoffed. "Tell us a bit about the peppermint plant…you know, how it came about, what you can use it for, that kind of stuff. And I don't want to see any of the rest of you writing any of this down, do you hear me?" he mock-growled at the class. "There will NOT be a test on this later; this is for you to KNOW and not for some stupid exam." Satisfied that everyone had put down their quills (even an irritated-looking Hermione Granger), the Guru nodded for Neville to begin.

"Well, uh, the peppermint plant as we know it was actually an accidental hybrid discovered sometime around the year 1696, when some regular mint plants happened to sprout and then interbreed with the plants in a spearmint bed. The plant can be used in a number of ways, but it's perhaps best known as the source for the volatile oil that bears its name…."

And with that, Neville was off to the races!

***

Some time (and a surprisingly informative and interesting talk about peppermint) later, the Guru gently broke in on Neville's spiel. "Okay, Neville, you've made your point, now shut it," he laughed, his tone taking any sting out of the words. "While you've been teaching us about peppermint, I've been dissolving as much candy in this whiskey as I possibly could, so now we have a supersaturated solution of peppermint candy—which, as you can guess, is mostly sugar—in whiskey. Now, who can tell me how I know it's a supersaturated solution?" he paused, and looked around expectantly.

When no one answered, the Guru made a disgusted sound, then turned to gripe at the silently glaring Potions Master. "Got them thoroughly cowed, don't you, Severus. Some teacher you are," he said, turning back. "Okay, this is a real easy one. By definition, a solution becomes saturated when no additional solute can be dissolved into the solvent…got it? So, in this case, the solvent is…what?"

"Er, the firewhiskey?" Draco ventured carefully, his face scrunched in concentration.

"Very good, Mr. Malfoy. 5 points to Slytherin. So, that would mean that the solute would be…what, Mr. Potter?" he asked.

Harry paused, thinking, then answered carefully. "The candy?"

The Guru grinned widely. "Absolutely right, 5 points to Gryffindor. See, this is really easy. Now, everybody look closely," he said, holding up the bottle. The entire class (except, of course, for the Professor, who was still trying to glare the Doctor to death, without much success) could see a layer of undissolved candy on the bottom of the bottle.

"Does it mean that…super-whatever thingy if you've still got candy left over in the bottom?" Blaise asked.

"Yeppers...see, a solution is supersaturated when you've gone beyond the point where any more solute will dissolve in the solvent. So, since I've been shaking this for the last few minutes without any change in how much candy is left over, I can say with confidence that the whiskey is supersaturated with the sugar from the candy."

"So…is it cough syrup yet?" a student asked.

"Not quite yet…but we're getting there." Turning, he picked up the small brown bottle labeled 'Oil of Peppermint' that the returning house elf had put there while Neville was talking. "Okay, so we've taken our firewhiskey—minus a couple of quality-control shots for the mixer"—he grinned, "—and dissolved as much peppermint candy in it as we possibly can, plus a bit more. Now, I'm going to add this entire bottle to the firewhiskey, and hope it doesn't blow the entire castle to Kingdom Come." At the horrified looks and immediate scraping of chairs being pushed back, he laughed. "Get back here, you cowards, I'm not going to blow up the castle…I think," he grinned. Then, carefully, he added the oil directly to the flask of sugared whiskey, then shut his eyes tightly closed.

Nothing happened.

The Guru smiled happily, then took a deep breath before suddenly yelling out "BOOM!" Setting the bottle down, he gave himself over to his laughter as the entire class (and one very irritated Professor) picked themselves up from wherever they had thrown themselves when he yelled.

"Gotcha, every single one of you," he snickered, shaking his head at the various glares he was receiving. "Okay, okay, five points to everybody for good reflexes, okay? Sheesh, none of you people can take a frakkin joke…."

"Oh, we're sorry…was that supposed to be funny?" Draco snarked as he smoothed his robes.

"Yeah, next time hold up a sign or something," Harry groused.

"Oh, you're just mad that you didn't think of it first," the Guru said, totally unrepentant. "Now, let's just give old Snapey his medicine, shan't we?"

Turning to the irate (but somehow, mysteriously silenced Professor), the Guru poured a generous dollop in the second shot glass he had requested.

"All right, Severus, down the hatch. I promise you that this will take away that nasty cough of yours." Holding it out, the Guru just stood there, one eyebrow raised in challenge until Snape reached out, snatched it away and downed it on one gulp.

Immediately the Professor's face turned bright red and steam poured from his ears as he made a face. "Gaaaaak," he said. "Horrible, absolutely horrible!" he protested.

"Why, Professor Snape…I would have thought that you, of all people, would realize that the taste of a potion is thoroughly immaterial to the efficacy of said potion, and therefore completely beneath the notice of the brewer." The Guru kept one eyebrow raised as he forced-fed Snape one of his own expressions. "In point of fact, the concoction I just gave you is a bit strong, but none of the flavors it contains are in and of themselves terribly noxious…unlike many of the vials of sludge you routinely foist on an undeserving world. Now," he said, turning a contemptuous back on the Professor, "the alcohol in the whiskey serves as a powerful mucolytic—who can tell me what a mucolytic is…?"

And, for the next five minutes, the Guru discussed the wonders of home made cough syrup at some length.

***

"So, sugar soothes the throat and promotes saliva production which calms the cough reflex, the peppermint acts as a decongestant and mild bronchodilator, and the liquor thins the mucus, thus serving as an expectorant. Any questions?" the Guru summarized.

"Surely you don't mean to suggest that…that muggle-derived brew could ever possibly replace a proper wizarding cough potion, do you?" Snape, having finally found his voice (without any coughing, oddly enough) snapped.

"Oh, I don't know…you haven't coughed once since we gave you a good dose, now have you?" the Guru asked coldly.

"My cough was merely the result of a temporary dysfunction…."

"Yes, yes, we know, your entire upper respiratory system went on the fritz, we heard, Snape! But, since you're so convinced of your superiority to me, let's see, shall we?" The Guru's eyes lit with a dangerous gleam. "Ask me three questions, any three questions at all. Then, I'll ask you three questions, and we'll see just who answers the most correctly. Fair enough?"

"Hmmph. I doubt that you'd be able to answer any questions which I might pose to a student," Snape said, his lip curling as he spoke.

"Oh, I don't know about that. I ought to at least know the kinds of things you'd ask, say, a little firstie named Harry Potter," the Guru replied, insolence bubbling in his voice.

"Very well, then tell me…what would I have if I were to add powered root of asphodel to an infusion of wormwood?" The Potions Master's eyes positively glowed as the memory of a previous humiliation danced through his head.

"Aside from ruining a perfectly good batch of potential absinthe, you mean?" The Guru's face was serene, even peaceful as he answered. "Drought of the Living Death. Although, I'd really rather make the absinthe, if it's all right with you," he went on as the class looked on in surprise.

"And where would you need to look if I sent you after a bezoar?"

At this, the Guru merely shrugged. "Anywhere in the alimentary tract, although classically they are described as being located in the stomach. Since a bezoar is, by definition, a mass of swallowed foreign material which fails to pass through the gastrointestinal system, anything with a gut can technically have a bezoar. Bezoars are usually composed of swallowed hair and fiber and typically are indeed located in the stomach, but the term is used to refer to any compacted mass of ingested material." The Guru shrugged. "I know the ones you most commonly use in making poison antidotes come from goats, but I'm personally aware of cases of pill bezoars being reported in the literature. The two most common types of bezoars are the trichobezoar and the phytobezoar, the first being primarily composed of swallowed hair and the second being predominately nonabsorbed plant fibers. Of course, there's always the rare case of Rapunzel syndrome, in which a trichobezoar extends from the stomach into the small bowel." He paused and shrugged again. "I could go on, but will that do?" His eyes twinkling, the Guru added as an aside. "I did a brief report on bezoars some years ago…what an interesting coincidence!"

Severus Snape closed his eyes briefly, fighting for composure. Then, opening his eyes, he tried one last time. "Very well. What is the difference between monkshood and wolfsbane?"

"Only the spelling, since they're both common names for aconite, which is an extremely potent neurotoxin. It can be fatal in ingestion, primarily by causing severe bradycardia leading to ventricular arrhythmia, cardiovascular collapse and death, and aconite poisoning is best treated with supportive treatment: atropine for bradycardia, activated charcoal following gastric lavage for acute ingestion, antiarrhymics with fluid and/or pressor support as indicated…will that be all, Severus?"

Snape nodded weakly, collapsing back into his chair. Damn the man! He'd been not only correct, but had inundated Snape with more information than the wizard had ever thought possible! And now, it was his turn, and he was already speaking….

"First of all, Professor Snape, I don't expect you to appreciate the subtle mysteries of high energy physics, the transcendent wonder that is molecular genetics, the elegance of physical biochemistry, to say nothing of the calculus! No, Snape, you're content with your little bubbling pots and smelly vials, making your fumes and stenches while mixing up puddles of glop I wouldn't pour onto a compost heap, much less give to a patient. You, with your claims of bottled fame, brewed glory and stoppered death; what can you offer me, a Doctor of Medicine and a Man of Science?" With this last, the Guru struck a heroic pose, one finger proudly waving aloft, his voice ringing out. "Tell me, Professor," he went on, rounding on the black-robed man, "what is the most singularly useful property of the DNA polymerase of Thermophilus aquaticus?" When Snape just stared at him, uncomprehending, the Doctor snorted in derision. "As any first-year muggle biology student can tell you, Taq 1 DNA polymerase is stable at high temperatures. Now, quickly, whose eponymous equations are used to adjust for observational differences between two separate observers moving at differing velocities?" He paused, smirking, as Snape gaped like a fish out of water. "How about if I gave you a hint: they also allow you to calculate the degree of time dilation and length contraction that occurs as one approaches the speed of light. Still no answer, Snapey? The Lorentz transformations. Zero for two, Professor. Care to try again?"

"Now see here!" Snape broke in angrily. "I hardly see how this…."

"Hardly see is correct. Still, you felt perfectly confident in grilling a certain muggle-raised firstie a few years back about potions lore that he had no way of knowing, didn't you? Aren't paybacks a bitch?" The Guru's smirk threatened to split his face while Snape sputtered incoherently. "I haven't asked you any question that I wouldn't expect any teen-aged muggle university student to know. Tell you what, let's make it a bit easier on you, shall we? Tell me, if you can, where I could find the Mohorovičić discontinuity? That one should be easy for a muggle student, the equivalent of a Hogwarts firsie."

Severus Snape drew himself up to his full height and attempted to look down his nose at the interloper in his dungeon. "I have no idea what you are babbling about, and I certainly wouldn't know about muggle topics," he said, contemptuously.

"Really? So, I suppose that the planet you're standing on has no interest to you? How…insanely provincial of you." Turning to the students, most of whom were now gaping at him openly, the Guru grinned. "The Moho, as it's commonly known, marks the boundary between earth's crust and its mantle. If memory serves, it was discovered by the Croatian gentlemen whose name it bears sometime in the early 1900's. It's important because earthquake P-waves travel much faster when they reach the Moho, which you need to know if you're going to do things like predict where tsunamis will hit and stuff like that."

"We are not generally prone to tsunamis in Scotland," Snape sneered, valiantly trying to recoup some of his shredded dignity.

"Huh. One decent-sized eruption in Iceland would pretty much take care of that, now wouldn't it? But never mind, Snape, you went zero for three, which is a perfect record." The Guru crossed his arms over his chest and regarded the professor with slitted eyes.

Snape exploded. "Now see here! I refuse to be treated in this manner in my own classroom! You cannot simply barge in here, disrupting my class and casting aspersions on me, my teaching style, and my knowledge of my Art. I could not possibly care less about your muggle science or your foolish questions, as they are of no value to any decent wizard!"

The Guru merely chuckled at this. "Oh, Snape, Snape, Snape. You pitiful, miserable excuse for a short-order chef…I've known french fry boys at Mickey D's with more skills than you've shown me. Well, except for the swirly robe thing, that's pretty impressive," the Doc conceded.

"Why, you…" Snape growled, whipping out his wand and pointing it at the Guru, only to pause when the Guru merely put his fingertip on the end of the wand.

"Ah, ah, ah, Snapey…temper, temper," the Guru smirked. "I wouldn't, if I were you. Oh, I might loose a finger or two, but do you really want to loose your wand arm? Think about it."

"GET OUT OF MY DUNGEONS!" Snape cried, his face turning a rather impressive shade of puce.

"Tell you what, Snapey," the Guru said, leaning back and taking his finger off of the end of Snape's wand. "Let's give it one more try, shall we? I'll have Longbottom successfully brew a mix using a collection of caustic and dangerous agents, while you make me a simple mix of two common household items. If Neville blows it up and you do fine, I'll admit that your potions skill is far superior to my science."

Snape snorted his derision. "I see no other possible outcome, certainly. Longbottom's a menace, and I doubt that he'd even be able to brew a decent cup of tea."

The Guru wasn't finished. "But," the fat man went on, eyes twinkling. "If Neville does well…and you screw up…then you concede to the better man, which is me. Deal?"

"Of course," Snape said, nodding his acceptance. Finally, he thought, with Longbottom involved how can I loose?

"Very good. I'll need the house elves to get me some supplies, but that shouldn't take more than a couple of minutes," the Guru said, turning to the elves that had not yet gotten around to being somewhere else. "Boys, here, let me make you a list." Pulling out his usual pen and little yellow pad, he quickly jotted down several items before handing the yellow note to the foremost elf. "I need these things prepped exactly like I've written down, okay? And be careful…I don't want you hurting yourself. Off you go!" When the elves disappeared, the Guru turned back to the Professor. "While they're gone, could I get you to set up a cauldron for you to work in? Preferably a medium-sized one, if you've got it handy."

"Of course, this is a potions classroom, after all," Snape huffed. "Mr. Malfoy, please bring me a medium cauldron," he ordered, turning to the Doctor. "Will a regular pewter cauldron be acceptable, or should it be of a special material?" he asked sarcastically.

The Guru pursed his lips. "Hmm…for what you'll be doing, it shouldn't matter." When Snape nodded and waved Draco onward, the Guru went on. "Neville's project, on the other hand…well, I was very specific in asking the elves for borosilicate glass, which is one of the few things nonreactive enough to be truly safe for what I've got in mind."

Snape just looked at him, unwilling to admit to having no idea as to just what 'borosilicate' glass might be. With a shrug, he turned away to supervise Draco as the Slytherin student set up the cauldron on a side table, well away from the student's desks.

The door to the potions classroom opened, and the three house elves pushed a kitchen cart in carefully. All of the students looked at it, hoping to get some clue as to just what the Guru had planned for his little demonstration. Unfortunately for them, the elves had taken the precaution of covering the cart with a cloth, and only an outline of the cart's contents could be seen.

"Ah, and here we are!" the Doctor said happily. "Excellent work as always, boys, give yourselves a gold star!" While the house elves wiggled with pleasure at the praise, the Guru took over the cart, pushing it to the side of Snape's desk. Pulling off the cover, he revealed…a rather uninteresting collection of materials.

Ignoring the signs of disappointment from the students (and Snape's feigned disinterest), the Guru began transferring the cart's contents to the desktop, speaking as he worked.

"Well, now, let's see…here we have our first ingredient," he said, lifting up a glass container in which a somewhat cloudy pale yellow fluid gently washed back and forth. "This is a freshly prepared extract of the fruiting body of C. limon, a highly dangerous substance. It contains not only a complex blend of aromatic and aliphatic hydrocarbons but a number of both simple and moderately complex carbohydrates, oils, and organic acids, most notably citric and ascorbic acids. It has a pH of between 2 and 3, which as I'm sure you know makes it strongly acidic," he said, looking around at the students, who obediently nodded cluelessly, "and would be terribly painful if I were to place it on certain delicate parts of your tender young bodies. So, guard you eyes carefully…you have been warned." With exaggerated care, he set the open container down, then picked up another cup, which held a white powder. "Here we have a quantity of the pure crystalline form of a disaccharide composed of a pentose and a hexose joined by a glycoside bond. With this as a base and a few common household cleaning products, I could make an explosive compound sufficient to blow the doors off the Great Hall." Setting this cup down near the plant extract, he lifted a large pitcher filled with a clear liquid carefully. "And here…pure dihydrogen monoxide, perhaps the single most dangerous substance on the planet! This stuff is so corrosive that it is often referred to as the 'Universal Solvent', and as little as two tablespoons of this is enough to kill anyone in this room. In fact, thousands of muggles and, I'm certain, dozens of wizards are killed every year by this benign-appearing liquid." Setting it down on the desk, the Guru looked out across the class sternly. "I do hope you appreciate just what a risk Mr. Longbottom is about to take," he said coldly.

"Bloody hell! You're going to let Longbottom play with that?" Blaise Zabini burst out. "He'll kill us all!" From all around the room, the Slytherins and Gryffindors found themselves for once in complete agreement.

"You would prefer to do it, Mr. Zabini? Perhaps in partnership with Mr. Weasley?" the Guru asked, the threat threading itself through his silky tone.

"Er, no, sir…not at all," Zabini answered. Looking at Ron Weasley, who was shaking his head in terror, Blaise shuddered, then dropped his eyes.

"I didn't think so," the Guru said. Then, he looked at the young man trembling at his side. "I have complete confidence that Mr. Longbottom can follow my instructions correctly, and that there will be no danger to any of you. In fact, I intend to drink the final product myself!" The fat man smiled tightly as eyes went wide around the room at that statement.

"Sir, are you sure?" Neville asked softly.

"Mr. Longbottom, I have never been more sure about anything in my life. Just do what I tell you, and nothing can go wrong. Trust me," the Guru finished warmly. "Now, let's get to it. First thing, I want you to completely dissolve all of the white crystals in the dihydrogen monoxide. You'll need to add it gently, and stir for at least a couple of minutes."

"Yes, sir. Should I stir clockwise or counter-clockwise?" Neville asked, his voice trembling.

"Your choice, Mr. Longbottom. However, I would suggest that you keep stirring in the same direction once you begin, until the last of the crystals has dissolved." Unconcernedly, the Guru stepped to the side just enough to allow Neville to begin carrying out his instructions.

To everyone's amazement, Neville's first task went off smoothly. He was perhaps a bit slow in adding the crystals to the clear liquid, but seemed to gain confidence when there was no immediate explosion forthcoming. Before long, his careful strokes had finished the dissolving process, and he turned to the Guru expectantly.

"Very good, Neville. Now, be careful of the extract, it's quite acidic. I want you to slowly add it to the monoxide/disaccharide mix, and stir it for thirty strokes in the same direction as before."

"Yes, sir," Neville said, then picked up the cup of liquid carefully. Biting his lower lip in concentration, he gently added the second ingredient, and once again the class was surprised when the process went smoothly. Thirty strokes later, Neville withdrew the stirring rod and looked up once more.

"Nicely done, Neville. Now, we'll just let your mix sit while Professor Snape shows us how to make a simple paste of sodium acetate. Are you ready, Professor?" the Guru asked politely.

"Of course. I trust you have components for me to use?" the Potions Master sniffed.

"Certainly. I asked the elves to bring me a cup of commercial-strength sodium bicarbonate—which will be the sodium source—as well as two cups of dilute acetic acid." He paused, then sighed. "I'd prefer to have used concentrated acetic acid, but since only a true chemistry lab would have that on hand, I had to improvise. That being the case, I'm afraid you'll have to use a 2 to 1 ratio of acid to bicarbonate, rather than the more customary 1 to 1 ration I'd prefer. Still, one must make do, mustn't one?" he asked, his tone dripping with condescension at the poor range of supplies available to him in this situation.

"I'm sure that I'll manage," Snape grated out, grabbing up the bicarbonate powder and tipping the entire cup into his cauldron. Then, ignoring the Guru's step back (and pulling Neville with him), Snape took the dilute acetic acid and poured a generous portion on top of the powder.

Instantly, the cauldron overflowed with whitish goo, spilling across the table and onto the floor before Snape could do anything to stop it.

"Bloody hell!" the Slytherin Head of House barked as he jumped back to avoid getting any of the sharp-smelling mess on his robes.

"Having a bit of a problem, Professor?" the Guru asked sweetly. "Can't keep it in the cauldron? Looks like you've made a bit of a mess," he offered, one hand gesturing the house elves to keep their places and not rush to clean it up.

"You knew this would happen, damn you!" Snape snarled, whirling on the Guru. "You specifically did this to humiliate me!"

The Guru shrugged. "Yep. Of course, it's not my fault that you've never been exposed to the old baking soda and vinegar volcano trick…which any muggle child over the age of eight could have told you about."

Ignoring Snape's sputtering; the Guru turned and picked up a shot glass from his earlier firewhiskey tasting. "Now, let's see just how Mr. Longbottom's mix came out. Anybody want to be the first to try it?" he asked, then chuckled when heads all around the room shook negatively. "Well, then…I suppose I'll have to be the guinea pig." With a flourish, he dipped the cup into the pale yellow liquid, pulled it out and put it to his lips, draining it all.

For a moment, he stood there, his face expressionless, his body immobile. Then, he smacked his lips and smiled. "Tastes great! Who wants lemonade?"

If the shocked faces that greeted his question surprised him, he didn't show it. Turning to the trio of house elves, he motioned them forward to begin serving the lemonade in the goblets that had also been part of his request list.

Neville was the first to recover his wits. "You…I mean, I…made lemonade?"

"Of course. What else do you get when you combine lemon juice, sugar and water?" the Guru asked innocently, his head cocked to one side.

"LEMONADE?!?! But…but…but…" Snape roared, then sputtered angrily.

"But nothing, Professor," the Guru said firmly, looking the other man directly in the eye. "Ordinary table sugar is sucrose, which is a double sugar made from a 5-carbon and a 6-carbon sugar joined together. Citrus limon is the scientific name for the common lemon tree, and dihydrogen monoxide…two hydrogen atoms and one oxygen atom…is nothing more than water. So, water, table sugar and lemon juice—what else does that make, if not lemonade?" He made his face as blankly innocent as he possibly could as he watched Snape work out just what he had been told.

"So…you tricked us all!" Snape spat. "And then, you have me to mix this…this…" he waved at the still-foaming cauldron.

"I had you mix two common items that I knew would make a glorious mess despite anything that you could do to prevent it, yes. Now, how did it feel?" the Guru asked, still maintaining eye contact.

Snape turned away in disgust as the Guru turned back to the class. "So, how's the lemonade?" he asked, pleased to see that everyone seemed to be enjoying it. "Now, let's talk about what I just did, and why I did it. Any thoughts? Yes, Miss Granger, go ahead," he said, indicating the muggle-born witch.

"You used scientific terms that Professor Snape wouldn't recognize, didn't you?" she asked carefully. Obviously, she still remembered what had happened to her earlier in the Great Hall.

The Doctor nodded. "Correct. Five points to Gryffindor. Who else has a comment?"

"You did it to humiliate Snape," Ron Weasley said, then flinched as the Professor whirled to glare at him.

"Also correct, Mr. Weasley; although for your sake, I'd probably keep on referring to him as 'Professor', if I were you."

"What you did wasn't fair!" Pansy Parkinson snapped. "Professor Snape can't be expected to know your muggle garbage."

"Maybe you're right, Miss Parkinson, and maybe you're not. Still, I had a very good reason for doing what I did…care to speculate what that reason was?"

"You wanted to humiliate Professor Snape in front of all of us…and make Longbottom look good at the same time," Pansy spat back.

The Guru nodded. "Correct as far as that goes, so 2 points to Slytherin. Anyone else?" he asked, scanning the room. When no one else dared to speak up, he frowned. "Nobody wants to venture a guess about why I went to all of this trouble? None of you Slytherins has figured it out yet?"

Draco raised his hand, and waited for the Guru's nod before he asked carefully. "Could you tell us how you knew the answers to the questions Professor Snape was going to ask you? Was it Legilimency?"

"Yes, you may ask, and no, it wasn't Legilimency. Actually, I was taking a chance with that, but I did manage to stack the deck in my favor." At the confused looks that his answer caused, he sighed. "I knew that Snape had tormented Harry as a first year with those three particular questions, and I also knew that I could answer them easily. So, when I challenged him, I made sure to plant a little mental seed about 'firsties' and 'Harry Potter' in his mind, and let Snape's subconscious mind do the rest. Just a bit of psychology, no wand-waving or hocus-pocus involved."

"So, you set him up," Harry made it a statement as much as a question.

"Absolutely. I figured that he'd make the connection between successfully tormenting you, Harry, and the chance to do the same to me. Imagine how he would have crowed had he actually been able to stump me with the same questions he used to humiliate you." The Guru turned to Snape, who was finishing with the cleanup of the mess he had made. "Wouldn't you have, Severus? You would have rubbed it into my face here, and again at least once in front of the entire school, if you could, wouldn't you?"

"I refuse to dignify these proceedings by answering you," Snape sniffed. "I find this so-called 'lesson' to be nothing more than an excuse for your own self-gratification through my embarassment."

"And there's the rub. Professor Pot, that makes me Doctor Kettle. Snape, do you really think that everyone at this school doesn't think that you do exactly that kind of thing on a daily basis? I just decided to give you a small taste of your own medicine…now how did you like it?"

Snape didn't answer, but he also refused to meet the Doctor's eyes. Harry, on the other hand, suddenly sat up in his seat and raised his hand.

"So, Doc…you wanted Snape to feel…like he makes us feel?" the Boy-Who-Lived asked.

"Very good, Mr. Potter, 10 points to Gryffindor. That's it exactly. Yes, Draco," he nodded to the blond Slytherin.

"And all of this was just to torment Professor Snape, then?" Draco asked, his voice neutral.

"Actually, no." The Guru became very serious as he hopped up to sit on Snape's desk. "There's a very important lesson here, if you'll let yourselves learn it. What I really wanted to demonstrate here today is that it doesn't take much to make even very smart people—like Professor Snape—look less smart and well educated than they are. All you have to do is catch them outside of their field, or area of expertise, and even the best of us can be brought down." He shrugged, and went on. "You'll find that there are people out there who will always delight in making your life difficult, and one of their favorite tactics is to pull you into their area and then put you down for not knowing their stuff as well as they do. It's childish and stupid, but it's also part of life as we know it. Often, the best that you can do is just to try to avoid these people, because they'll probably never, ever change." He paused and accepted another cup of lemonade from one of the house elves. "I have no doubt that most of you could write up a test on your favorite subject—like, Quiddich, maybe, or your favorite subject—that I couldn't pass in a million years. That doesn't mean that I'm stupid, or that you're especially gifted in that area, it only means that you know things that I don't. It doesn't make you superior, or better than me…it just makes you look like a complete and total wanker, ultimately." Looking around the class, he noticed a few eyes widening in understanding, a few more narrowing as they absorbed what he had said, and a few with frankly blank looks of complete and total incomprehension. Oh well, he thought, lead a horse to water and from there it's up to them. "Professor Snape, care to try some of Longbottom's really excellent lemonade?" he asked cheerfully, making an overture to the Professor.

Snape still looked at the Guru as if he was debating which Unforgivable to cast first, but he did accept a cup from a house elf. Sipping it, he nodded minutely. "Well, I see that in this case, Longbottom's performance was adequate. This time," he finished sourly.

And at that, the Guru winked once more at Neville Longbottom, which brought a tiny smile to the Gryffindor's lips.

It really was excellent lemonade.

A/N: Yes, I know Snape's not the Potions Master in Year 6. Yes, I know that Neville wouldn't be in the post-OWLS class with Snape for all the tea in China. Did I mention that this is a crack!fic, and an AU one at that? I'm sure I must have at some point along the way….

Yes, this really is an old family recipe for cough syrup, and it works well. The scientific terms are as scrupulously correct as I could make them. The Guru actually fudged a bit, but not much. The Lorentz transformations are college-level material, but Taq 1 and the Moho are both high school science-level material. Of course, the physical biochemistry and treatment of aconite ingestion came sometime later. Note that the Guru worked hard to 'talk up' Neville's ingredients while downplaying Snape's as inconsequential and innocuous—another bit of psychological misdirection and obfuscation. And, if you've never done it, mixing vinegar and baking soda is REALLY impressive, in a foaming, messy way.

So why did the Guru do all this? Because (a) Snape really deserves it and (b) who better than the Guru to feed him this bitter pill?

Next Chapter: assuming I get reviews for this piece of fluff, the next chapter involves the Room of Requirement, an announcement to the student body, and the problem of horcruxes.