Some might have thought it odd to place a library in the hollow of a tree. The humidity generated by the living wood was not an ideal environment to keep books, ensuring that the librarian needed to constantly refresh the enchantments on the shelves that kept the books dry and protected from moths. While it was quite wide by tree standards, the floorspace available was still narrow by the standards of a traditional structure, requiring the library to build upwards in order to fit its stock. Most libraries of such a small scale did not require a ladder to reach half the books available to it. Lastly, the more superstitious might point out that nothing good could come of using a tree to house the pulped and pressed remains of its kin.

However, whatever may be said about its dubious quality as a library, the great oak near the center of Ponyville was an excellent site to hold sleepovers. There was a surprising number of spare pillows available. There was a spare bed, and, as a result of insight from the night Rarity and Applejack had stayed over, a spare spare bed. Twilight had a whole pile of makeup and mane-styling accessories in the bathroom—gifts from Rarity, nearly every one of them—that were only ever brought out for the sake of the makeovers that her book, Slumber 101 and its sequel, Slumber 201 both insisted were a necessary part of the sleepover experience. The kitchen was well-stocked with all the ingredients required for proper s'more construction.

Perhaps most importantly, however, the walls were made to dampen sound, allowing guests to plot out pranks in hushed whispers without fear of discovery by their host.

“Did you bring it?” hissed Rainbow Dash, keeping her eyes trained on the door to the kitchen where Twilight was busy hunting down ingredients for s'mores. Dash had hidden the chocolate in the bottom left cupboard, so she knew they had at least five minutes while the unicorn checked each drawer systematically from right to left and top to bottom.

Pinkie Pie produced a small clay vial—from where, Dash was afraid to guess—and gave her a conspiratorial wink. “Of course!”

Dash took the vial in her hooves and grinned. “Awesome. Zecora said it would work?”

Pinkie nodded. “Yep! Just a little bit should do the trick. She said to be careful not to get any on your lips, or it'll affect you too!”

“That'd blow the whole thing,” Rainbow Dash agreed, carefully tucking the vial under her wing. She offered a hoof-bump to her friend. “You and me, Pinkie, we're gonna get back on top of our game. No egghead is gonna out-prank us!”

Pinkie grinned and reciprocated the gesture. “Well, except for the one time when she did. And the second time, when Rarity tried to get back at her. Three times, if you wanna count the time she turned Big Mac into a mare for a day.”

“That one doesn't count,” insisted Rainbow. “My point is, we're Ponyville's pranksters, not Twilight, and tonight she's gonna find out why that is.”

“Aha!” Twilight's voice issued from the kitchen. “Found the chocolate!” She emerged from the door, levitating graham crackers, marshmallows and a stack of chocolate bars behind her. “It's always the last place you look, isn't it?”

Rainbow chuckled and grinned sheepishly. “Yeah, funny that.”

The slumber party went as smoothly as could be expected. The pillow fight was spirited, pitting Dash's uncanny agility against Twilight's capacity to levitate every pillow in the library at will and Pinkie's inexplicable ability to be everywhere at once—Rainbow accused her at one point of keeping a clone from the mirror pool. Ultimately, the fight had to be called a draw before they ran out of usable pillows to sleep on.

Without Rarity present to egg them into it, makeovers came and went without much fuss, until Pinkie came up with an idea to frizz up Dash's mane and call her Rainfro Dash. In response, a few hairties turned the earth mare into Pigtail Pie. Twilight put her mane in a bun, but nopony could think of an entertaining pun for it, so she took it out.

Spooky stories and Truth or Dare ended up being rolled into one, as Pinkie Truthed Rainbow Dash to tell her the scariest story she knew, and Dash Dared Twilight to try and do better. The two of them shared classic campfire tales, while Pinkie followed up with a curiously disquieting story about every day being just a bit too sunny and everypony being a little too cheerful.

After a good deal of fun times and memories, it was finally time to go to bed. Given how active she was in the daytime, it was unsurprising that Pinkie fell fast asleep the moment she hit the pillow. Dash, being an expert napper, soon followed. Twilight had a little more trouble than her guests getting her eyes to shut. Nothing was really keeping her awake, but frequent late-night study sessions had gotten her body used to staying up well into the night.

She tossed and rolled in her bed for a little while before finally dropping her hooves to the floor to quietly tip-trot down the stairs into the kitchen. Twilight illuminated her way with a dim charge from her horn, careful not to make it bright enough to wake her guests.

Smacking her dry lips, Twilight levitated her favorite mug—a simple ceramic vessel with her cutie mark printed on the side—from the counter. She yawned as she filled the cup with water. It did not always work, but occasionally a little drink would help quell her insomnia. Twilight lapped at the cool, clear liquid.

The glow in the room began to brighten. Twilight winced and tried to extinguish her horn, only to realize the light was not coming from her horn. A soft but slowly intensifying light emanated from her own coat, bathing the kitchen in lavender luminescence.

She suppressed a yelp of surprise and stumbled back, her pupils shrinking both out of shock and exposure to light. She was radiating light like a giant purple firefly. Twilight twisted her head as she heard a couple of ponies snickering behind her.

Rainbow Dash and Pinkie peeked over the crest of the stairs, giggling. “Hey look, Pinkie,” said Dash, pointing her hoof. “It's Night-Light Sparkle!” The two mares fell over each other in laughter.

Twilight's eyes flickered back to her mug. The rim of it now had a golden, glowing substance smeared across where Twilight's lips had touched it. She rolled her eyes and gave her friends a good-natured chuckle. “Firefly dust on the rim. That's clever, you two. Very clever.”

Rainbow Dash slapped her knee with a wing. “I was beginning to wonder if you were ever going to drink from that cup! You're like a camel!”

The cup levitated in Twilight's magical grip as she studied it, rubbing her chin with a hoof. “How did you keep the stuff from glowing when you applied it?” she asked.

“We went to Zecora for that,” Pinkie supplied, bouncing happily. “She mixed it with some starch and a berry I can't remember the name of!”

“Duskberry,” Twilight ventured, nodding appreciatively. “I should've tasted it. The duskberries absorbed the light from the firefly dust, but they break down as soon as they meet the moisture in my lips. The dust takes effect, and I start glowing like a sign at an all night cafe.” She studied her luminescent hoof with an expression of academic satisfaction at having unraveled the mystery.

Rainbow waved her hoof dismissively. “Yeah, sure, probably that. The point is, we got you good. I mean, when we can see your expression reflected in shadow puppets on the wall, that's pretty good!” She turned to Pinkie, who was busy rolling on the floor giggling. “Didn't we get her good?”

Pinkie snorted. “We got her pretty good,” she agreed.

Twilight smiled graciously. “All right, you girls got me pretty good, I'll admit.”

“Ponyville's best pranksters!” Rainbow hissed, offering a hoof-bump to Pinkie, who returned it with enthusiasm.

Twilight yawned. “But I think now it really is time for bed. Good thing firefly dust doesn't last very long,” she said. Indeed, the glow emanating from her coat was already beginning to dim. She finished her glass of water and herded her guests back upstairs.

*-*-*

The next morning, Twilight Sparkle was larger. Or perhaps her bed was smaller. At any rate, where once her legs had a little space to reach for the ground when she rolled out of bed, this morning her hooves easily touched the smooth hardwood of the floor without ever leaving the covers. She yawned, muttering to herself something about fully investigating the cause of this after breakfast.

She stopped as she felt two pairs of eyes on her. “Oh, good morning, Pinkie, Rainbow Dash. I hope I didn't wake you. I was just going to get some breakfast. Would either of you two like anything?”

Pinkie and Rainbow Dash simply sat upright in their guest beds and stared, their mouths gaping open in shock. Perhaps it was a trick of perspective, but they seemed somehow shorter than Twilight.

After a few minutes of stunned silence from her friends, Twilight shrugged and started down the stairs. Addled by drowsiness, she stumbled on the first step, but fortunately her lavender wings opened up to stabilize her as she made her descent. Her expression registered something odd about this, but once again she repeated her vow to have breakfast before figuring anything out just yet.

She hummed an idle tune as she fixed herself a mug of coffee and a bowl of oats. The oats clinked together pleasantly in the bowl, and the coffee gurgled and percolated nicely. The granular meal was crunchy and just sweet enough, and the coffee managed to cool down enough by the time she drank it that she could call it just right.

Her breakfast thus completed, Twilight trotted back up the stairs, where her two friends remained in their beds, still frozen in shock.

“Now then,” she said, addressing the pair. “Pinkie, do I have wings?”

Pinkie Pie blinked. After a moment's hesitation, she nodded.

“I see,” said Twilight, nodding. “And I didn't have them last night, right? This isn't something I just didn't notice the whole time?”

Pinkie shook her head.

“Good, good. Now Rainbow, am I... taller than normal?”

Rainbow Dash nodded.

Twilight took a deep breath. “Okay. So, I'm taller, and I have wings now. Is there... is there anything else?”

Pinkie and Rainbow shared a glance. After a while, Pinkie cleared her throat. “Your uh, mane's all sparkly.”

“It is,” agreed Rainbow Dash. “I wasn't gonna say anything, but it totally is. Sparkly, and a bit, uh, floaty.”

“I was afraid this might happen,” said Twilight, shaking her head. “It was those duskberries.”

Rainbow sputtered, “The duskberries!? Twilight, berries can't do this! Look at you, you're a—you're an—”

“Well, no, not the duskberries by themselves, no,” Twilight said. “This isn't your fault, you couldn't have known I had dawnberries for breakfast yesterday.”

“Dawnberries?” Pinkie Pie asked.

“Yes, dawnberries. And I'm sure you both know what happens when a particularly magical unicorn eats dawnberries and duskberries in the same day, don't you?” She met with a pair of uncomprehending stares. “Well, you don't think Princess Cadance was born with wings, do you?”

Rainbow Dash shook her head. “Nope. No way. Nice try, Twilight, but I'm not buying it. These are like, fake wings, or something.” She got out of bed and reached out with a hoof to grab her wings. They were warm, and they moved on their own, and the feathers felt very, very real.

Twilight winced, and with a few beats of her purple wings lifted into the air. “Ow! Uh, please don't do that, Dash, that hurts.”

Rainbow stumbled backwards, her eyes going wide. “C-C-Celestia, they're real!” she stammered.

Both Twilight and Rainbow Dash winced as a high-pitched, happy squeal issued from Pinkie. “Omigosh, Twilight, you're a princess! I've never gotten to throw a coronation party before!” The bed squeaked and groaned as she bounced on it. Pinkie used it as a springboard to launch herself at Twilight in a flying hug.

“I—ack—don't think that's how royalty works, Pinkie,” gasped Twilight as pink hooves squeezed her. Pinkie's grip loosened and Twilight let her down to the floor. “But it still would be a good idea to let Princess Celestia know about this. Do you think you two could go find Spike for me, please?”

“Okie dokie, your highness!” Pinkie Pie trotted down the stairs and out the door, humming the Equestrian national anthem as she went.

Rainbow Dash remained in place, staring vacantly for a few minutes before finally shaking her head and taking to the air. “Hey Pinkie, wait up!”

Twilight went out on the balcony to watch the pink and blue dots disappear into the streets of Ponyville. A bluebird perched on the railing and chirped cheerfully to her. She smiled at the bird and whistled back to it. She heard hoofsteps behind her. “Did I do okay?” she asked.

A smaller, wingless Twilight joined her on the balcony. “That was incredible! You saw their faces, didn't you? They totally believed it!”

“Indeed, darling, you performed marvelously.” Rarity joined the two Twilights, grinning. “Wonderful quick thinking dear. 'Dawnberries,' I loved it! Where did you learn to improvise like that?”

The taller, winged Twilight smiled. “Well, I—” she coughed as the voice-alteration candy's effects wore off. “Oh, excuse me,” came Fluttershy's own soft voice. “See, Thursdays are improv night for the bunnies and me. You should see Angel Bunny's Hoity Toity impression. It's really good.”

The two unicorns helped Fluttershy out of the stilts she had been wearing to look taller. Rarity removed the enchanted wig, which halted its unearthly shimmer as it was removed from Fluttershy's head. Rarity had spent quite a few bits to get her hooves on a wig that both had the right colors and also had the sparkling enchantment on it to imitate the Celestial Sisters' famous manes. She had ended up painting the pink stripe on it herself.

Twilight glanced out over Ponyville. Pinkie and Rainbow Dash could still be seen galloping across the plaza. “I wonder how long it's going to take them to remember Spike is in Canterlot for the week?” she mused.

Rarity shrugged. “I suppose this little joke could potentially backfire on us if they go all the way to Canterlot and tell the Princess themselves. Still, I would call it worth it.”

Fluttershy's wooden horn clattered to the ground. “Oh my!” the pegasus shrank back, hiding behind purple-dyed wings. “D-did I just commit treason?” she squeaked. “When I agreed to help you two, I didn't even think... is impersonating a princess a crime? Taking care of a sick bird was one thing, but I don't want to get banished for this!”

“Relax, Fluttershy,” said Twilight, placing a hoof on her friend's shoulders before she could start hyperventilating. “For one thing, you were impersonating me, not a princess. And even if that still counted, Princess Celestia loves a good practical joke. You've got nothing to worry about.”

“A-are you sure? What if the Princess doesn't think it was funny?”

“Then Twilight and I will take full responsibility for it,” Rarity placated.

Fluttershy nodded. “Okay. But, um, if it's all the same to you, I think I'm going to go home and wash this dye out, and start working on an alibi.” She gathered up her things and slipped out the back door, darting from bush to bush in an effort not to be seen.

“I can get Aloe and Lotus to swear you were at the spa all morning, if you'd like,” Rarity called after her.

“Eep!” Fluttershy disappeared in a purple blur.

Twilight put a hoof to her chin, blinking at Rarity. “Actually, I'm still not sure why you agreed to help with this, Rarity,” she said. “Not that I'm not grateful. Your disguise was great; Fluttershy and I couldn't have done this without you,” she added, “but I thought you were still trying to get back at me for the one prank over teatime. What happened to 'nopony pulls one on Rarity Belle and gets away clean?'”

“Ah, well you see,” Rarity chuckled lightly. “I've found a new, more productive motto for myself.”

Twilight raised an eyebrow. “Oh? And what is that?”

Rarity leaned against the railing. “If you can't beat them, join them.”

Author's Notes:

Boy, did the season 3 finale take the wind out of this chapter.