It is often said among ponies that there are few places as quiet and peaceful as a library. Actually, this isn’t true; it is very seldom said at all, but if it were it would nonetheless be an accurate expression. Some would attribute this abundance of peace and quiet to the invariably draconian methods of the librarians, others would cite the inherent silence of the sort of activities that normally take place within a library, while still others would declare this all to be a moot point on the grounds that hardly anypony really visits libraries anyway.

On this particular Saturday afternoon however, the Ponyville library was neither silent nor peaceful. Tomes, scrolls, and codices alike trembled upon the shelves as a series of booming hoof-beats pounded their way up to the front door. A moment later the door burst wide open, revealing a very upset white unicorn, followed closely by her yellow pegasus companion. The scorned mare strode furiously into the library, fully intent upon regaling all those present with her tale of woe, only she couldn’t because there was nopony there. At least not at first.

Within seconds, the door to the library’s basement flew open as Twilight Sparkle and Spike hurried into the room.

“Rarity, what’s wrong?” asked Twilight.

“What’s wrong?” repeated a distraught Rarity in a distraught voice so that it could be made abundantly clear just how distraught she was. “What’s wrong? I’ll tell you what’s wrong! It’s those two! This time they’ve gone too far!”

Twilight did not immediately answer, but instead shifted her gaze to the timid face of Fluttershy. Given Rarity’s penchant for melodrama, it was usually best to gauge the actual severity of the situation by observing the state of those around her. True to form, Fluttershy did not appear distraught in the slightest, although Twilight did notice something odd about the way she kept sucking on her tongue.

“Okay, you got me. Who’s gone too far?”

“Who do you think?” hissed Rarity. “Who else would assail me with such mischief?”

“Rainbow Dash and Pinkie Pie then?”

“The very same!”

“What did they do this time?” asked Twilight, trying her best not to smile and failing.

Rarity flared her nostrils in indignation. Normally she considered this to be a vulgar act, but in this case she elected to make an exception.

“I’ll tell you what happened. Fluttershy and I were enjoying a nice relaxing cup of tea at my place when we heard the chime of the doorbell. So I answered the door, and what should I find upon my front step but...” she paused mid-gesture. “A lovely box of chocolates.”

“You didn't,” said Twilight, with a roll of her eyes.

“But of course. I simply cannot turn away such gifts just because they are sent anonymously. What if I actually do have a secret admirer?”

Twilight opened her mouth to argue, but decided against it. Best to pick her battles.

“I suppose I can’t argue with that logic.”

“Anyway...” continued Rarity. “I brought them inside and opened them, and then of course I had to share them with Fluttershy...”

“And let me guess,” said Twilight with a smirk. “Hot-sauce?”

“Oh that’s putting it mildly, darling.”

“I think Pinkie Pie’s been experimenting,” said Fluttershy, her usual soft tone rendered hoarse by Pinkie Pie’s volcanic confectionery.

Twilight snickered.

“Are you laughing at me, Twilight?!” shrieked Rarity.

“You make it too easy. Seriously, how did you not see that coming?”

“Um, I kinda saw it coming,” said Fluttershy sheepishly. “But then Rarity offered me one, and I just couldn’t say no...”

Twilight could restrain herself no longer. Collapsing into a nearby chair, her peals of laughter filled the room. Spike however, remained serious as he hurried to comfort the slighted Rarity.

“Twilight, how can you be laughing at a time like this?” said the young dragon. “Can’t you see that Rarity’s upset?”

“I’m sorry,” giggled Twilight. “But come on, you two walked right into that one! Besides, it’s just a prank, all in good fun right? It’s not like Rainbow and Pinkie are hurting anypony.”

At that moment, the front door to the library burst open for the second time that afternoon, permitting entry for the stoic orange figure of Ponyville’s premier apple farmer.

“Hello, Applejack,” said Twilight, cheerily ignoring the serious expression upon her friend’s face. “What brings you over?”

“Rainbow Dash n’ Pinkie Pie are what brings me over!” said Applejack rather loudly. “They’re on another of their little prankin’ sprees!”

“And so now you’ve come to either warn me or to vent your frustrations at me...” said Twilight, with a good-humoured roll of her eyes. “So which is it?”

“Er, to be honest, a bit o’ both I guess.”

“Well I’m afraid Rarity has beat you to the punch on both accounts,” said Twilight.

“Oh, they got you already?” said Applejack, turning to the other unicorn.

“Me and Fluttershy,” nodded Rarity. “Got us both with a thoughtful box of hot-sauce filled chocolates.”

“Well that don’t sound too bad.”

“Oh trust me, Applejack, I doubt even Princess Celestia could’ve handled them, and she works with a big ball of burning gas every day, if you’ll pardon my vulgar language.”

“So what did Dash and Pinkie do to you, Applejack?” asked Twilight with a smile.

“Well, me an’ Granny Smith were in the kitchen workin’ on a batch of apple pies an’ listenin’ to the radio. Suddenly the music just stops and this live news cast thing comes on, goin’ on about how the police’ve tracked down a gang of apple smugglers and how they’re just about to bust in and round ‘em all up!”

Rarity, Fluttershy, and Spike leaned in closer as Applejack told her story. Even Twilight was intrigued despite herself.

“It sounded mighty interestin’, so I turned up the volume, and suddenly they’re shoutin’ over the loudspeaker that they’ve got the place surrounded and for them crooks to come out with their hooves to the sky. But it ain’t just comin’ from the radio, it’s coming from right outside!”

There was a collective gasp of disbelief at this development in the story.

“I kid you not, girls,” said Applejack. “So naturally, Granny Smith gets all up in a panic, so it was up to me to tie my apron around a broom handle and head on out to let ‘em know there’s been a huge mistake. But when I got out there, there weren’t no police; just Rainbow Dash and Pinkie Pie with a big ol’ radio-microphone-thingy and me lookin’ all stupid.”

Twilight started laughing again.

“T’ain’t funny, Twilight, they darn near scared Granny Smith half to death!” shouted Applejack angrily.

“I’m sorry,” giggled Twilight. “But come on, I’m sure they didn’t mean any harm.”

“I don’t doubt it, girl,” said Applejack. “But that don’t make it any less harmful.”

“Somepony needs to teach those two a lesson!” huffed Rarity.

“Oh come on, Rarity,” said Twilight with a shake of her head as she turned to a nearby bookcase. “Those two? Pinkie Pie’s almost impossible to reason with, and as for Rainbow, well, frankly she’s as stubborn as you are, Applejack. No offence.”

“None taken, I know what you meant.”

“I’m sure they’ll come around and apologise later on,” said Twilight as she magically summoned to herself a particularly unremarkable old tome. “But for now it’s best to just let them have their fun. Now if you’ll excuse me, I have some studying to-”

Before she could finish, a great bang like a gunshot suddenly rent the air, followed by a violent ripping noise as a startled Twilight magically tore the book she was holding in twain. The purple mare wheeled around just in time to see Pinkie Pie and Rainbow Dash quivering in hysterics outside a nearby open window. Rainbow was holding a red and white striped megaphone, while Pinkie was clutching the ruptured remains of a brown paper bag. In horror, Twilight looked down upon destroyed book that now lay on the ground before her, then back to the two pranksters, and then back to the book, before resorting to a tried-and-true anger management technique of bursting violently into flames. The two mischievous mares yelped at the sight of Twilight’s sudden immolation and promptly fled the scene.

“Oh my...” squeaked Fluttershy.

“Now that’s just bad luck,” sighed Applejack.

Rarity cautiously approached her still smouldering friend.

“I’m not the sort to say ‘I told you so’, Twilight...” she murmured as she magically picked up the two torn halves of the book.

After perusing the damage for a moment, she gently pressed the two halves together. After a moment’s concentration the destroyed volume was engulfed in a nova of white light and made whole therein. Satisfied with her magical handiwork, Rarity passed the book back to Twilight.

“Thank-you Rarity,” seethed Twilight as she gingerly took the repaired codex.

“Not a problem, my dear,” said Rarity with a cautious nod.

Twilight’s enraged inferno seemed to have served its purpose, for as she leafed through the restored book her features shed their mask of anger and formed anew into a wide, thin-lipped grin. Applejack suddenly found herself feeling rather uneasy; she had seen that look on Twilight’s face before. She hadn’t much cared for it then, and the passage of time had done little to improve its appeal.

“Rarity...” Twilight said at last. “What was that you were saying before? About teaching Rainbow and Pinkie a lesson?”

“Now hold on there, missy!” interrupted Applejack. “Just what’re you thinkin’?”

“I’m thinking the same thing you and everypony else is, A.J.,” grinned Twilight. “I’m thinking we ought to give Rainbow Dash and Pinkie Pie, Ponyville’s Premier Professional Pranksters, a taste of their own sweet medicine!”

“Pardon me, darling, but isn’t that just escalating the conflict?” asked Rarity.

“Not at all,” said Twilight sweetly. “We just need to show those two that while pranks can be a lot of fun, sometimes they can take things a teensie bit too far. Which is why I propose we pull off a little prank of our own... You girls interested?”

For a moment, the four onlookers exchanged nervous glances. Finally, Applejack broke into a wide grin and stepped forward.

“What the hay. Y’all know I just can’t pass up a chance to show up ol’ Rainbow, now can I?”

“Count me in as well, Twilight,” said Rarity eagerly. “Just because I am a lady doesn’t mean those two should have all the fun.”

“Well, if Rarity’s in, then so am I!” declared Spike.

The rest of the group now turned to the timid holdout.

“Well Fluttershy?” asked Twilight.

“Oh, well, um... sure, why not? I’m in,” Fluttershy finally conceded with a smile.

“Right, so what now, Sugarcube?” asked Applejack.

With a flourish, Twilight magically swept her book high over her head before leveling it in the direction of the basement door.

“To the Book-Cave!”

Moments later, the four ponies and one dragon were gathered around a polished steel table in the centre of Twilight’s basement laboratory. All around them was the hum and whir of various machines and electronics, many of which served absolutely no practical purpose whatsoever other than to shield the library from potential budget cuts. Even the monolithic computer that dominated the room was of dubious value to the public, despite the long sleepless nights Twilight had spent trying to program basic software onto it with varying degrees of measurable success.

“Right,” said Applejack. “You got a plan, Twi?”

“That I do, Applejack,” smiled Twilight, still holding her book aloft. “Ironically, Rainbow and Pinkie have inadvertently suggested to us the means for our little... prank. For behold!” She slammed the book upon the table. “The Big Book of Experimental Alchemy!”

“Er, what’s alchemy?” asked Applejack.

“It’s like chemistry, but magic!” explained Twilight. “You know, magic potions and such.”

“I thought that stuff was all a load o’ hooey?” said Applejack quizzically.

“Most of it is,” conceded Twilight. “But as our dear friend Zecora has shown us time and again, there do exist naturally occurring substances with inherent magical properties that can be combined to produce various effects. This book contains some of the less... conventional formulae. And I just so happened to have noticed one that should work out very nicely indeed...”

Twilight flipped open the cover and magically rifled through the pages before settling on a recipe about halfway through the book. Spike leaned over the table to read the title aloud.

“Doppelganger... Draghit?”

“Draught, Spike, ‘Doppelganger Draught’,” corrected Twilight, briskly reading through the description opposite the formula itself. “Essentially it’s a potion that causes the imbiber to take on the appearance of somepony else.”

Rarity reacted to this revelation with visible revulsion.

“Look like... somepony else? Somepony who isn’t yourself? Why, how horrid... anypony you wish?”

“Well, you do need a ‘sample’ of the pony in question to mix into the potion, y’know like hair or blood or-”

Fluttershy suddenly let out a horrified squeal.

“Well, ideally not blood,” continued Twilight. “Also, it only affects the really superficial things like hair and eye colour, so it’s not like an exact match.”

“And just what’re we supposed to do with somethin’ like that?!” asked Applejack.

“It’s simple,” said Twilight. “We’re going to make two batches of the Draught; one of Rainbow Dash, and one of Pinkie Pie. Then, we swap ‘em up!”

A short pause followed.

“I’m not sure I follow, Twilight,” said Rarity at last.

“Well let me put it this way,” said Twilight. “How would you react if you woke up in the morning, went to look in your bathroom mirror, and saw Pinkie Pie staring back out at you?”

“I’d assume Pinkie Pie was in my mirror,” said Fluttershy matter-of-factly.

“Okay, bad example,” admitted Twilight. “How would you react if you saw Rainbow Dash staring back out at you, then?”

Applejack, Fluttershy, and Spike remained at a complete loss, but Rarity’s face suddenly lit up with a look of realization, which quickly reconstituted itself into a mischievous grin.

“Why Twilight Sparkle, you devious filly, that’s brilliant!”

Realization soon dawned on the rest of the gang.

“Oh I get it now, the ol’ switcheroo!” smiled Applejack.

“Oh Rainbow is going to freak out!” giggled Fluttershy.

“Very nice, Twilight, very nice,” nodded Spike.

“Well, no sense in wasting time,” said Twilight. “Let’s get to mixing!”

Preparing the Doppelganger Draught took the rest of the afternoon. Under Twilight’s direction, Spike had been sent to gather outstanding materials, while Applejack and Rarity were enlisted to acquire the all-important “samples” that would allow them to turn Rainbow Dash and Pinkie Pie into “Pinkie Dash” and “Rainbow Pie” respectively. Fluttershy was to remain behind and assist Twilight in mixing the potion itself.

Rarity had taken to her task with great enthusiasm, believing that the experience would be akin to her favourite romantic detective novels, in which the private-eye protagonist would triumphantly discover evidence of the suspicious dame’s passing upon her used hairbrush, at which point the dame herself would arrive on scene and the situation would subsequently become rather steamy (beyond this point, Rarity suddenly became rather embarrassed and refused to say any more on the matter, though the blush on her face did much to undermine her in this regard). She and Applejack had insisted they would be gone for merely thirty minutes; as it occurred, it was well over two hours before they returned.

“What kept you?” asked Twilight.

“We ran into some... complications,” said Rarity. “As it turns out, neither Rainbow Dash nor Pinkie Pie are much in the habit of brushing their hair.”

“Well shucks, I coulda’ told ya that, Rarity,” said Applejack. “But in the end we figured out a ‘plan B’, so it all worked out.”

Rarity magically placed two glass phials upon the table, each one containing several strands of hair. The first sample was a uniform shade of hot pink, while the second was a nonuniform shade of every colour but pink.

“Uh, where did you get these, exactly?” asked Twilight, noticing now that the hairs were invariably tangled and clumped and seemed rather damp as well.

Rarity hesitated to answer.

“Well, it was Applejack’s idea, you see, so...”

“We pulled ‘em outa their shower drains,” said Applejack briskly and without shame.

Rarity shuddered.

“Oh quit the drama, girl, it’s not like ya had to touch ‘em or anything.”

“It’s not so much that I had to touch them, Applejack, it’s more the fact that I had to get anywhere near them that’s bothering me,” said Rarity.

“What matters is that you got the samples, girls,” said Twilight, eager to prevent an argument before it began. “Now come over here and see what Fluttershy and I have cooked up.”

Twilight led them over to where Fluttershy was carefully attending to two small cast-iron cauldrons, each filled with a bubbling cream-coloured sludge. Twilight carefully emptied the contents of each phial into a cauldron. The boiling brews bubbled violently for a moment, before their colours suddenly changed to suit the subject of their effects; the first cauldron’s contents became a vibrant shade of pink, while the other’s changed to a rich sky-blue.

“I been meanin’ to ask, Twilight, but how are we gonna get ‘em to drink this stuff?” asked Applejack.

“Funny you should ask, A.J.,” answered Twilight. “Turns out it isn’t a potion you drink after all. It’s actually a candle.”

“A... candle?” responded Rarity incredulously.

“Yeah, apparently you just light it up and it works by inhaling the fumes.”

“But then why is it called a draught if it’s not something you drink?” asked Rarity.

Twilight shrugged.

“I guess they meant like a draught of air or something. It’s funny, I know. But we followed the recipe, and this is what it said. Anyway, the good news is that now all we have to do is set them up somewhere next to them, and then sit back and enjoy the fireworks.”

“Twilight, it’s ready,” announced Fluttershy, gesturing to the two cauldrons.

“And now for the final step.”

With the utmost caution, Twilight magically poured their mixtures into a duo of candle molds that Spike had acquired earlier from the local candlestick-maker’s shop. Almost immediately the enchanted wax began to set.

“Right, now that that’s done, we need to start planning for phase-two,” said Twilight. “I believe our best course of action will be for somepony to sneak into their houses tonight after they’re asleep and light these candles by their bedside. They’ll inhale the fumes while they sleep, and when they wake up the next morning...” Twilight permitted herself a giggle. “Ideally, we want somepony who’s very good at keeping quiet...”

“Yes, somepony with grace and subtlety...” added Rarity.

“Somepony who won’t have any trouble gettin’ into both a cloud house and an upper story apartment...” continued Applejack.

“Yeah...” said Spike. “Somepony who can... uh... ah, to heck with it, I vote Fluttershy.”

“Eeep.”

“Oh come now, Fluttershy, it’ll be fun,” said Rarity sweetly. “And you are the best pony for it.” The glamourous unicorn suddenly gasped in faux alarm. “But you’ll need a disguise of some sort, some stealthy raiment to help you remain unseen in the darkness of the night. Perhaps one of my Mare-Do-Well outfits would work... No, too garish; that particular shade of purple is simply not suitable for such delicate work. I suppose I’ll just have to whip up a whole new outfit! Come, Fluttershy, we haven’t a moment to lose!”

Before Fluttershy could protest, Rarity had already dragged her out the front door of the library, leaving Twilight and Spike to see off Applejack.

“Well, I’d better mosey on off,” said Applejack. “See y’all tomorrow mornin’, okay?”

“Be here around five o’ clock,” said Twilight. “I want us in position first thing in the morning. I just hope that Fluttershy delivers.”

“Don’t worry about her none,” smiled Applejack. “She wants to see this just as much as we do. Anyway, g’night, Twi.”

“Do you really think this’ll work the way you said?” asked Spike later that evening, after Fluttershy had collected the candles.

“Why wouldn’t it? We followed everything according to plan,” said Twilight. “Absolutely everything. What can possibly go wrong?” Twilight suddenly shuddered. “Woah, did you just feel a chill?” she asked.

“No,” answered Spike.

“Huh, weird. Anyway, let’s get you to bed, Spike. We have a big day tomorrow...”