The familiar image of Twilight Sparkle reading a book on the train was different in two ways: Twilight's cutie mark was on the book, and was missing from the flanks of its usual owner, to all apparent others on the train. But the other ponies on the train chalked it up to some magical disguisery Twilight was studying and didn't think twice about it, if they even noticed at all.
Twilight's six friends, however, realized it with every encounter.
"You even SOUND like Pinkie Pie," Rarity said, looking into Pinkie's now-purple eyes as Pinkie looked up from The Book of Sparkle to watch the other ponies on the train again.
"What do you mean? I thought I sounded like Twilight, if a little echoey. Hello. Helooooo. Hellllloooooooooo."
"That's exactly how I mean, darling. While our Twilight does enjoy her science, she usually doesn't go at it in the middle of a conversation as you do, dearie."
Twilight explained, "The effects you're talking about, Pinkie, are caused by sound waves reverberating in the skull. You always sound a bit different to other people as you do to yourself."
"heloooooooooh … I THOUGHT something was a bit meedely-beadley about all this."
Applejack looked up suddenly from her own window-gazing, "THAT'S what you found all … meedely-beadilwhatsit? Not suddenly lookin' like Twilight?"
"Well, that's not really a meededly-beadley. It's more of a 'bingy-boingy-bouncy-castle'."
"Ya, you're right." Spike was looking at Pinkie's eyes instead of Rarity's, for once. "You can tell it's not really Twilight right away." he snickered a bit as Pinkie looked over the train-car again, "She pony-watches instead of reads."
"I like how she still bounces up and down when she walks," Fluttershy smiled.
"Same with Twilight." Rainbow Dash added, "Pinkie Pie would never go on about head re-vibrations."
"Well, she ASKED," Twilight smiled as she defended herself laughingly, "Anyone who can ask the question deserves an answer."
"I'm wonderin' what the other ponies might say. Are we keeping this a secret or aren't we? And what am I supposed to tell them when these two start acting all funny? You know I'm no good at lyin'." She was looking down at her orchard far below, looking like a little kid's toyset far off in the distance.
As the train slowly spiraled up the mountain, everyone pondered this question, and a number of others. As the train went though the tunnel on the final approach to Canterlot, it was slowly rolling to a stop.
"Did they really have to stop inside the tunnel?" Rarity complained. "Couldn't they have waited until we were out?"
"I'm sure they have a good reason to," Twilight looked up from her own book and out the slightly-less-dark window. She could see the light at the end of the tunnel; and it was getting smaller, not bigger, as the train jerked into motion again. Strange, the train seemed to be backing up of all things, reversing faster and faster.
The realization hit her in the very pit of her stomach, as she figured it out:
they weren't reversing at all. The train was rolling downhill. It was out of control!
Faster and faster the train sped. Bits of luggage tumbled down. Other ponies started to figure it out, as well.
Twilight, thinking fast, reached up and pulled the emergency stop. And pulled. And yanked for all her worth.
It didn't accomplish much.
"Are we going to crash?" Fluttershy was three-quarters into hiding under her seat, narrowly missed by a huge bag. Bags were tumbling across the traincar. Ponies dived for cover as they were divebombed.
Twi thought fast again, "Pinkie! Please tell me You've gotten through chapter one of my book."
"About how magic is an allegoryoryory- just like life?"
"YES!"
"Oh yeah, I'm on chapter three now. Well, chapter two. Three. Is the number "3" part of chapter 2 or 3?"
"I need you to make a magic bubble shield for the train to bounce into."
Pinkie fidgeted and looked down. "Um."
"Come on Pinkie, we need a bubble to take up the train's momentum. You like bubbles. Imagine a HUGE bubble. You can even make it pink."
"Or BALOONS. A pink balloon!"
"Yes! A pink balloon. Imagine it in your head. Now imagine pushing all the air into the balloon."
"It's going all Pssssspppphhhhhhh all over the place."
Twilight stopped a second. Twilight thought. How do you explain magic to someone who's never known it before? How would you explain a new color to one who'd never seen it? How would you write about a song to someone who'd never heard it? Could she even explain it so Pinkie could understand?
"Remember the movement spell? Or light spell? The magic in your horn? "
"I can do that." Pinkie looked up and focused on her horn so magic filled it, and it started glowing brighter.
"Put the magic in your balloon."
"What? But where is the balloon?"
"In your head."
"But it's in my imagination. Is that a place?"
"You need to make it a place."
"How do I do that?"
Twilight wasn't sure this was going to work on such short notice. Drat! She should've taught Pinkie about spells last night. But there was no knowing this would happen.
The train was still careening backwards and picking up truly ridiculous speed. They may not make the next bend in the tracks.
She didn't want to think about that.
"Pinkie," Fluttershy broke the silence. "Remember at your last party you showed me how to work the helium tank, even though I was afraid of breaking it?"
"Yeah?"
"You need to let Twilight show you how to work your magic tank. Fill your balloon. Don't be afraid. you're not going to break Twilight's spell. Just let it fill your balloons, and everything is fine." Fluttershy smiled up at Pinkie, leaning out from under the seat, and standing on two front hooves, "I have faith in you."
Pinkie Pie closed her eyes and imagined her balloon in her mind's eye. Just like on her cutie mark. She pushed all the magic into it and it gradually inflated, and got bigger and bigger. And bigger! More magic. More inflation. Pinkie opened her eyes and there was a solid pink, sparkly magic balloon around all seven of them.
"You did it. Keep going!" Twilight encouraged Pinkie.
"How big does it need to be?"
"As big as the train!"
"We're going to need a lot of helium."
Her eyes still open for reference, Pinkie shone more brilliant pink magic into the balloon's space. With every grain of it, the balloon inflated in size. Pinkie thought of all the parties she'd ever thrown and how much helium they'd all needed, how many times she'd entertained all her friends; all their happiness. All their laughter. All their friendship.
She slammed her eyes shut and dumped every ounce of happy helium into her balloon, and …
pow
With the tiniest sound, the train started to slow; and instead of the sudden, jarring stop of a crash, instead they felt the slow, easygoing slooshing around of a perfect dive onto a bed of feathers … or a baloon.
The train rolled to a perfect stop. The entire mountaintop had been enshrouded in a truly titanic, massive pink bubble, larger than the entire city of Canterlot and the mountaintop besides. The train was gently resting on one edge of it, and though the bubble had deformed, the train could not go over the side.
Pinkie looked out the window, "Maybe I overdid it?"
Rarity tentatively felt the edge of the bubble with one hoof, resting it on the barrier, and smiled. "No, Pinkie. It's perfect." She continued on, "I'd hate to be the one to go on a magic duel against you. This balloon is magnificent!"
Dash said, "I'd hate to be whoever's been pulling these pranks on us, and keeping us from Celestia."
Rarity agreed. "Whomever sabotaged the train must be very desperate. Maybe we should go in disguise? I didn't bring any costumes, but …"
Twilight smiled a big, toothy Pinkie smile. "Oh don't worry; if Pinkie can pull it off, I know just the spell."