Warning: The story contains humiliation, messy diapers and living suits

So, I never really wrote a story about my arts before, but I've had people asking me if I would in the past, so I decided to give it a shot, I guess.

*Clears throat*

.................................................

Rainbow Dash was a fearless Wonderbolt. Whenever she was sent on a mission, she looked whatever she was dealing with straight in the eye.
With her jealousy-inducing speed and fierce physical strength, she was a force to be reckoned with.
So, when Spitfire sent her on today's mission, she didn't think much of it.
She was certain it was going to be another walk in the park, as always.

The cocky pegasus landed on a meadow in The Middle Of Nowhere, a plain that got its name for being in the middle of nowhere.
She had no idea what the threat could be around here, except maybe locusts.

"Heeeeey!! What's up!? I hear there's some creature problem around here!?"

She yelled out, but she didn't really know what she was expecting. For a random pony to pop out of the grass and give her instructions? She was alone here.
That's what she thought, until she turned around and almost suffered a heart attack from the sight of something big standing behind her.
Upon closer examination, it was a weird textured entity, looking kind of like a blank pony model.
It had a kind of chubby and weird looking shape of a pony, but it had no mane, no tail, no ears, not even a cutie mark or a face. It was colourless, dull grey all throughout.
The strange creature looked at her. Or she wasn't looking at her, until bright purple eyes suddenly grew on its featureless face.
It blinked at her a few times and slowly, the bottom part of its face stretched out and formed the shape of a snoot like it was clay.

"Hehe, heyaaa!! You're a cute one! What's your name, little fella?"

The pegasus stumbled back. Not because the voice was scary, but because it sounded like her own.
A little squeaky and bubbly, but definitely hers.

"SQUEAK!! Pretty mane! Soooo rainbow! What's your name, doll?"

The mass shook its head and, like rolling out a rug, fluffy rainbow curls poured down its shoulders, bouncing around gracefully.
Rainbow's ears dropped. A shapeshifter!? She's never heard of anything like that before. Was it dangerous? Must be. That's why they had to call in a Wondebolt.
Still... What was with the diaper though? So weird...
While Dashie was brainstorming, the entitiy rubbed its face, forming it into a more pony-like shape, but with big pointy ears and blushy cheeks.

"Quicky speed, super sweet! What's your name, darling?"

"R-Rainbow Dash..."

The mare finally got herself together and actually answered its only question. It wasn't looking hostile right now...

"Rainbow Dashie! Mashy Dashie! Hehehehe!!"

It giggled gleefully, spinning around, which seamlessly changed its colourless body into a shiny Wonderbolt suit.
Rainbow's eyebrow twitched. Her vision flashed red. Only those who trained hard and dedicated themselves to the Wonderbolts had the right to wear the iconic outfit.
A silly-looking creature like that one...
Stealing her 20% awesomer-than-anypony look was bad enough, but this was just unacceptable.
Nopony made fun of the Wonderbolts on her watch!
The shapeshifter before her shook its backside, a curly rainbow tail popping out of it.
It was now finished. Before her was standing a bubbly, silly, ridiculous, cutesy, girly, diapered version of herself.
If they made a filly's baby doll of Rainbow Dash, she'd look like this.

"Teehee! You're an adooorable pony Dashie! We're gonna be besties! Gonna have sOooOoo much fun together!"

It clapped its big hooves together squeakily and made a clumsy step towards the mare, giggling stupidly.
Even though it was almost twice her size, she wasn't scared.
She's fought much bigger.
She grit her teeth, leaned down, spread her wings gracefully and thrust herself at the fraud with great power.
She yelled as she kicked it with great force, hitting the soft mass and making it stumble back a few steps, almost falling over.
She smirked, her muscles sparkling with adrenaline. The creature was slow as all hay!
The smirk quicky faded though, as she realised she couldn't pull her hoof out of its stomach.
Or where its stomach was supposed to be. It was all just one big mass and it was heavy, like she kicked a big blob of molasses.
Furthermore, as she tried to pull back, she realised the mass had a grip, and it was pulling her hoof deeper.

"Oop, wowie! Sooo faaast! Pwecious wittle Wondiebolt!"

The fake Dash said, towering above her.
Rainbow desperately tried to free her hoof, placing her other two hooves on its belly to gain leverage, but as she tugged, she felt her support hooves sink into the mass as well.
Mistake! She made a dumb mistake!

"Awwwiiiieee, Dashie want cuddles?"

The mimic smiled sweetly, spreading her hooves around the trapped mare for a big hug, incapacitating her completely.
Even a champion knows when they're defeated, and so Rainbow started screaming for help as the creature hugged her closely, sinking her deeper and deeper into itself.
But nopony could hear her. She was in the middle of nowhere.
She started flailing her body around in panic, though it didn't move much.

"You bucking monster!! LET ME GO!! Oh, you're gonna wish you-"

She was forced to close her mouth as her head was plunged into the mass along with the rest of her body, making any sort of movement next to impossible as she sank further into the middle.
She couldn't escape. She seriously got defeated by a sissy piece of jelly.
She was sure the situation couldn't get any worse, when she felt something around her waist.
Her legs and arms were spread apart to fit the limbs of the big pony suit, and with that, the massive diaper pressed on her.
She blushed hard. None of this made sense. This had to be some sort of a sick prank. This creature must have been made by some weird magic, it just didn't make any sense.
Why? Why would anypony-

"Yipee!! I finally have a new bestie to play with! I can already feel we're all connected! This is the best day ever!!"

The pegasus decided to risk opening her eyes. Instead of just seeing suffocating darkness like she expected, she realised she could see the outside world. She could see it from a higher point than she was, though, and everything had a weird and slightly distorted purple look.
It struck her. Somehow, she could see through the monster's eyes. This was definitely foul magic.

"But da best part is, now we can go potty together!! Potty buddiesss!"

She felt the mimic outside say, sending a shiver down her spine.
P-potty buddies? What is that supposed to-
She suddenly felt pressure in her gut.
There's was no way the creature could-
She felt the creature bend over and "Hnggg" quietly. Her heart started racing as she realised what was about to happen.
It gave her new strength to squirm and struggle, but it was fruitless.
With a big grunt that rid her of all her dignity, she filled the creature's diaper. She clenched her teeth in disgust as the warm mess was kept in place, not like when using the toilet.

"Phee-ew! That was such a big load, Mashy Dashie! I'm so proud of you!"

Dash wished Tartarus would swallow her right here and now. Her ears were tomato red and burning from humiliation.
She had never been so degraded in her entire life.

"I can't wait to show everypony how cute you are! I can see aaaall your friends in your silly little memories? ISN'T IT THE COOLEST THING?? Like, twenty percentos!"

Dash screamed internally at the mere thought of somepony seeing her life this.
She gathered all the power she had left, and with one big punch, she burst through the belly of the beast, making a small hole through it and sticking her head out.

"NOOOOOOO!! LET! ME! OOOUUUTTT!!"

"Oh! Hi bestie! I can tell somepony's suuuper excited! I'll make sure to hurry uppie! BOOP!"

The boop from the heavy hoof pushed Rainbow back in her squishy prison, the hole getting smaller and smaller until it was mended, before the mare could even react.
She felt the mass get even denser.
She was now truly struck.
They were set in motion as the fraud suddenly started whistling and skipping playfully, making Dash bounce around in her own mess powerlessly.
And she couldn't do a thing.

Later that afternoon, the Mashy Dashie felt the absolute mortification of parading through Ponyville, ten messes in, exclaiming out joyful sissy phrases and pretty much making her presence known to everypony in at least the same continent.
Rainbow Dash later told Discord, who it turned out was behind the entire thing as a revenge for one of Dashie's pranks, that she forgave him.
It wasn't true at all.
But she decided it was better to NOT be his enemy.

"Hey Rainbow Dash?"

A little filly's voice snapped her out of her walk-around-the-town daydreaming.
She swung her mane back majestically.
She was always fond of giving out autographs to the little ones.

"Uh-huh?"

"Can you say the iconic funny line, please? You know... Bathrooms and toilets are silly and lame, but cute poofy diapies are my middle name! Rainbow Diapie Dashie!"

Rainbow Dash knew damn well:
She was never gonna live it down.