A diapered competition

by Tacs Repaid

Rating: mature
Tags: Princess Luna, Princess Celestia, Sex, Slice of Life, My Little Pony: Friendship is Magic
Length: 3107

Celestia and luna have a competition to see who is the biggest foal.

Celestia and Luna have a competition to see who is the biggest foal by doing what else, but seeing who can stay in their diaper the longest.
The fic occurs after MLP Season 7, Episode 10, so if you want to avoid spoilers, don't read.

Contains: diapers, diaper usage, scat scenes

Published 2017-06-01 15:20:01 UTC
Last updated 2017-06-03 09:13:57 UTC

1. How it all started

Author's Note

This chapter does contain any diaper wearing or sexual themes. However, this will change soon in the story, so be warned.
Also, any feedback will be greatly appreciated. Constructive criticsm on grammer, text, characterisation will be welcome.
This is my first time writing fanfiction, so I need all the pointers I can get.
And thank you for reading.

1. How it all started

Chapter 1:

How it all started

Celestia yawned. It was the yawn of a mare who had spent the whole day trying to fix the mistakes somepony else had made. The fact that the pony who had made those mistakes was her sister made no difference. She was Celestia, princess of Equestria, a pony who was the epitome of responsibility, caring and a role model for thousands of fillies and colts, along their parents and their parent’s parents. It would just help if she hadn’t spent the whole of last night fighting of Starlight Glimmer’s evil interpretations of her and her sister.

Flicking though the last pages of a document, she signed her name at the bottom, then with a burst of will, a golden seal appeared beside her name, proving its authenticity. Her last piece of paperwork done for the day she leant back in her chair, ready for a well-earned two-minute bre- >POP< A dark blue alicorn appeared in front of Celestia in a flash of arcane light.

“Arghhh!” Celestia let out a high-pitched scream but quickly stifled it with her hoof. “Luna, how many times do I have to ask you not to teleport right in front of my face?”

“Tia, stop being such baby, it wasn’t that scary.” Luna said with large grin of her face.

“I was not scared, merely startled.” Replied the larger alicorn, trying to regain her composure, “Anyway, why did come here, you know it’s half an hour until it’s time to raise the moon?”

“Aww, was little Celly afraid of the big bad blue pony?”

“I wasn’t scared I-”

“Do you want me to check under the bed to make sure that the boogymonster isn’t there?”

“Knock it off.” Celestia gave her sister a playful shove. “Getting back to the point, why did you come down so early?”

“I wanted to see how you handled the um, incident of the school field trip. I do hope those fillies manage to go on their trip, I will not be able to forgive myself if they cannot go because of me, besides that dream was horrible.”

“Now who’s the baby? The princess of dreams being scared of a little nightmare, please.” Celestia relished the opportunity for the little jab at her sister, it was not her who had started the little argument.

“I’m not the one who had a night light shaped like the sun until Starswirl had to help you get over your fear of the dark.”

“I wasn’t the one who wet themselves when she first saw a manticore.”

“Well I didn-”

“Hang on, hang on!” Celestia put a large hoof over her sister’s muzzle, “Let’s not fight, this is exactly why Starlight was sent here, to stop this petty squabbling.” Lowering her hoof, she continued, “What if we had a little competition, to prove who is the biggest foal out of us?”

Luna gave out a little chuckle, “Well we both know who would win that competition.”

“And who would that be?”

“Me of course.” Both the sisters laughed at this. Between the two of them, Luna was known to have the most competitive nature.

Stifling the last of her giggles, Celestia spoke, “So, do you have any idea what to do for this competition?” Both the alicorns sat in silence for about twenty seconds before-

“I’ve got it!” A blue hoof shot into the air. Blushing slightly at her outburst, Luna continued, “We could both wear diapers.” This was not what Celestia was expecting.

“Really Luna.” She gave her sister a slow clap, “Stop joking around and help me think of an idea.”

“I’m not joking.” Celestia gave her a raised eyebrow, “Just listen to the idea okay.”

“I’m listening.” Came the slightly sarcastic response.

Not put off by her sister’s tone, Luna continued, “Well what’s the most foalish thing you can do? It’s wearing a diaper.”

“I don’t see how-” Now it was Luna’s turn to cover her sisters mouth.

“Let me finish. Now the only thing more foalish than wearing a diaper, is being changed out of your diaper. What I propose is that the one of us that manages to stay in a diaper the longest without being changed is the victor, and when the loser gives up, they have to ask the other pony to change their diaper.”

Celestia laughed, “That doesn’t sound so hard, I would win that competition in a-”

“And when I said stay in a diaper, I mean no taking of your diaper what so ever, under no circumstances.”

Realisation dawned of Celestia, “Augh, no Luna, that’s disgusting.”

“You said you wanted a competition.”

“Well I didn’t think that such a competition would include me defecating in my undergarments.”

“Come on Tia, it won’t be that bad. Or, are you too much of a foal for this challenge? Is little baby Celly scared of a little diaper? Do you need to put a little dummy in your mout-”

“Okay, I’ll do it.”

With those words, although she did not yet know it, Celestia had signed herself up for a very, very interesting week.

“Well then, it’s settled, diapers will be our challenge. Tonight I will come up with the rest of the details and give them to you tomorrow morning while you get some well needed, well-deserved rest.” With that, Luna’s horn began to glow, signalling a teleport spell being cast.

“Hang on wait!” Celestia tapped Luna on the nose, “To answer your previous question, yes, I was able to raise enough money for those school fillies, under your name as well.”

“Thank you Celestia, that, that really means a lot to me.” Luna pulled her sister into a quick hug, then teleported with a flash of blue light, leaving nothing but a small wisp of smoke and a warmth in her sister’s heart.

“Luna,” Celestia thought,“I am so glad you back.”

With that happy thought, Celestia finalist her paperwork, double checking the signatures and making sure that all the documents were in the right place. Lifting her checklist up, she marked of the second-to-last box. The last box read “Lower the sun,” and in bold print, “and make sure that Luna raises the moon.”

Starting up, Celestia looked at the clock, “Luna!” she shouted, and quickly teleported away in a flash of golden light.

2. The contract

Chapter 2:

The Contract

Celestia sat at the table, two large plates of banana topped pancakes in front of her. The sun streamed through the windows leaving a lovely golden glow to place. The air was peaceful and >BOOM< The door slammed open and in rushed her sister, obviously exited.

“Sister, I do believe that I have come up a very good plan for our little competition.”

“Is that so.” Celestia raised an eyebrow, “and when did you have time to plan this, surely you were busy all of last night helping ponies with their dreams?”

“I can multitask. Anyway, here it is.” With that the blue alicorn thrust a sheet of parchment across the table to her sister. Looking down at the parchment, Celestia took note of what her sister had written. “Well what do you think?”

The diaper cannot be taken of at any time, for any reason.

You may not use magic to clean the diaper at any point.

No magic can be used to hide the sound or sight of the diaper. Magic can be used to mask the smell, but it must be continually cast, not as a permanent enchantment.

If anypony discovers your diaper, you may not tell them about the competition.

An enchantment must be cast over our flanks to kill all harmful bacteria in the diaper during the competition.

An enchantment must be cast to prevent rashes under the diaper and to make sure any stool in the diaper does not dry out and cause irritation to our fur and skin.

We cannot cast magic on each other that will directly ruin the competition. i.e. Removing clothing covering up the diaper.

If the diaper gets too full or begins to leak, you must place another diaper over the first.

When a participant gives up, they must go to the other and say, “NAME, I’m the foal, please change me.” At which point the winner must change them out of the diaper and clean them up.

If at any point one of these rules are broken, the guilty will be given a suitable punishment by the other participant.

“Really,” Celestia looked up, “We are going to have to continually create an air tight bubble about our flanks, can’t we just place an anti-odour glyph on the diaper?”

“Come Tia, what is so bad about a little risk? It won’t be fun without it.”

“Okay okay, but there is one thing I would like to change.”

“Which is?”

“The, “for any reason,” part. If there is something that threatens Equestria during the competition, or we must make a very important diplomatic meeting, the competition has to be cancelled so we have the best chance of working at our best. I won’t have Equestria threatened because of this deal.”

“Understood sister, understood.” There was a brief pause in the conversation, both pony’s minds flashing back to the many trials and tribulations that came with being ageless rulers of a kingdom, frequently assailed with many dangers and immortal enemies.

“So,” Celestia said, breaking the silence, “Are you going to have some pancakes?”

“Definitely,” replied the younger alicorn, “I cannot believe I missed out on these for so long, you really are an excellent baker.” Digging into her pancakes, she continued, “So when are we going to do it?”

“In a few weeks, I want to wait until my appointments are a bit less demanding, and I still need to finish the trade agreements Yakyakistan, you know how they get if things are not perfect.”

“Well then sister, I look forward to beating you.” She gave her older sister a sly smile. “Well, it’s time for me to hit the hay, so to speak, see you in the morning.” With that, Luna finished her pancakes and trotted out the door to her bedroom.

Author's Note

Well this is the last chapter of set up, the rest will include lovely diapered ponies.
As I said previously, any criticism is greatly appreciated.
Thanks for reading.

3. Baby steps

Chapter 3:

Baby steps

Three and a half weeks later…

Although she would never admit it, Celestia was excited. After all, it wasn’t that often that she got to do something so risqué. It was evening, Celestia had finished all her work and was waiting for Luna to arrive with the, “Packages.” She was nervous to, how was she going to hide her diaper, what would happen if the public found out. All these and a million other worries flashed through her mind as she waited for her sister.

Then, interrupting her thoughts, her sister teleported into her room, carrying two large, nondescript brown bags. “Luna you’re here, are those the, um, the diapers?”

“They most certainly are, and you had better be grateful, getting diapers made in your size was next to impossible.” She tossed one of the packages over to Celestia, “Go on then, open it.”

With a slight hesitation, Celestia opened the package. Inside were five, very large, very thick white diapers. Looking more closely, she saw that a golden sun was printed on each of diapers.

“Wait Luna, you had my cutie mark printed on them, why?”

“I thought that you would appreciate the camouflage.” Looking round, Celestia saw Luna holding up her diapers. They were a dark blue, matching her coat perfectly, and like her own, had they owner’s cutie mark printed on them.

“How did you get these made?” Asked Celestia, “Surely ponies would have asked why.”

“Oh, don’t worry about that, I have made some connections with certain ponies since my return, and I trust them to keep this confidential.”

“May I ask who?”

“No, you may not. Sorry for keeping secrets, but she specifically requested that I keep her identity secret. The only way I found her was by stumbling upon her dream, she does not openly flaunt her business.”

“Okay, sorry I asked.”

“Don’t worry Tia, you did not know. So, do you want help putting them on.”

“Don’t worry, I’ll be fine. How hard can it be to put on a diaper?”

With that, Celestia took the top white diaper from the pile and opened it. It surprised her how large the diaper was when it was laid open on the floor, the white padding crinkling as it was shifted.

“Okay then, here goes nothing.” She said to herself, and sat down in the middle of the diaper. The diaper felt soft beneath her, almost cushiony in texture. With that done, Celestia pulled up both sides of the diaper and taped them together. Looking up, she saw to her surprise that Luna was already in her diaper with a hoof in front of her mouth, obviously stifling a giggle. “What’s so funny?” Luna turned around so that her diapered flanks faced Celestia, looked over her shoulders and said.

“Do you notice anything about my diaper?”

“Like what, it makes your bum look big.”

“Look at my tail.” Sure enough, Luna’s tail was poking through a small hole in the back of the blue padding. Looking back at her own diaper, Celestia saw that her tail was poking up through the waistband of her diaper, the ever-flowing ethereal mane spiralling out in odd directions.

“Oh, don’t worry, I’ll fix it.” She reached down to her waistband, her hoofs clumsily beginning to untape her diaper. Luna gave out an exasperated sigh.

“Let me do it.” She walked over to her sister, “Right, spin around and lay down.”

“Luna, I can do it myself, it’s not that hard.”

“Let me help you sister, after all, diapers were made to be put on by somepony else.”

Celestia relented, “Just do it quickly.” She did as her sister asked and lay down in front of her, diaper up in the air. Luna quickly untaped the diaper, freeing Celestia pastel coloured tail.

“Lift up your tail.”

“I beg your pardon.”

“Lift up your tail so I can fit it in the hole.”

Blushing a bit at her sister words, Celestia did what was asked of her. Luna slowly threaded her tail through the hole and folded the padding over her flank. Then using her magic, Luna taped up the diaper nice and tight, “There, all done.”

Celestia looked down at her diaper. She had to admit, with her tail probably out of the way, the diaper felt almost comfortable. “So this is it then, these are not coming off until the competition is over.”

“Quite right sister, are you ready to cast the spells?”

“Yes Luna, I am ready.”

In truth, Celestia had spent a rather large portion of time studying these spells. They were very different to the spells that she normally cast, and some of them were rather tricky.

“Ok, you do me first, then I will do you.”

***

After a good ten minutes of casting, the spells were complete. Now, finally, the competition had begun.

“Tia, you had better get some sleep, it is going to be a busy day for you tomorrow.”

“Don’t worry, I will. So what are you going to do now?”

“I,” Replied Luna, “am going to go put on a dress.”

“Why?” Luna gave her a quizzical look.

“To cover up my diaper of course, seriously Celestia, your diaper is going to be discovered immediately if you keep thinking like that.” With that, Luna teleported out of the room. With Luna gone, Celestia picked up the rest of her diapers and also teleported…

… to her room. She quickly locked the door and closed the curtains. With precautions out of the way, she finally got a chance to look herself in the mirror. There she saw herself, Celestia, princess of the sun, ruler of Equestria, wearing a large white diaper. “I do look rather cute don’t I.” She thought to herself as she shifted around, trying to get a look at her diaper from all angles.

One thing she noticed, was how loud her diaper sounded when she moved around. Admittedly it was only a soft crinkle, but in the room all by herself, the noise seemed to fill the whole space. She also found out that the diaper pushed her legs slightly apart. While this wasn’t really a problem, she could still quite easily close her legs, she couldn’t just ignore it either. Every time she walked, the padding shifted and reformed, pressing itself against her inner thighs.

Eventually, Celestia got tired of admiring her new accessory in the mirror, and moved over to her wardrobe. Inside were many, many dresses. Although she was not too overly keen about fashion, living a few millennia meant that invariably fashion changed so much that new dresses were necessary, even if the old ones had not yet run their course.

Digging about in the back of the wardrobe, she eventually found the style of dress she was looking for. About eight hundred years ago, for some reason, her dress maker had decided to make a small line of dresses that would poof out at the back, making her flank look much bigger. “Perfect.” she thought to herself, “These should hide my diaper perfectly.”

Taking out the dress, she hung it up on a small hook on the door to her en suite. Her attire sorted for the next day, Celestia took of her regalia, brushed her teeth, and got into bed. Under the covers, the diaper gave her lower body a warm glow, like an extra pillow between her legs. Celestia smiled, there was something very nice about this. The diaper gave her a sense of comfort, almost like when she was a child with Starswirl looking after the two of them as they slept. Snuggling up against her pillow, she quickly fell into a deep, blissful sleep.