A study on Sodium Polyacrylate

by Foal Star

Rating: teen
Tags: Twilight Sparkle, My Little Pony: Friendship is Magic, Fetish, Comedy, Princess Celestia, Slice of Life
Length: 10392

Twilight decides to wear a diaper while studying. But somehow it gets stuck to her rump the next morning before her big test.

Twilight Sparkle decides to try wearing a diaper to help her save time while studying. It sounds like a good plan in theory until she finds out the next morning shes stuck in the diaper. Worse off she has less than two hours to get ready for her test. So Twilight has a choice to skip her test to save herself from embarrassment or take the test in a diaper....

Cover artist: Kurikia

Published 2018-10-23 17:30:01 UTC
Last updated 2019-01-20 07:03:57 UTC

Chapter One: Absorbency, Check!

Chapter One: Absorbency, Check!

In a small cozy study in a giant tower that stood over Canterlot. Inside there was a single simple desk made of oak, with a few thick books placed upon it. Each book contained various magic spells. A few sat open next to an ink pot with a dozen scrolls lying about notes scrawled across them. Near the desk was a big window and beyond it the clear dark night sky with glittering stars and the full moon with its light illuminating the room. There was even a very comfy brown couch in the back of the room. In the middle of the cozy, simple room, a young purple-coated unicorn named Twilight was laying on her back exposing her belly on a big poofy pink changing mat. It was an odd feature in such a simple room designed for studying. Even the studious mare knew this, and despite her respect for places of learning she gave the gaudy object a sheepish smile and whispered, “the only reason I’m doing this because I don’t want to use the bathroom while I study I need to get a hundred on tomorrow's test.”

Twilight took out a big white bottle within a sparkly a pink aurora over her rump and carefully began to sprinkle the white powdery substance over her crotch and tush. She looked on with her tired purple eyes gauging the amount of powder that should be added to her seat and whispered, “slow and steady that’s what the book on proper foal care said. I have to make sure to cover the entire genital and rump is completely with the white powder.” The mare continued to pour the powder making sure to cover every inch of her purple fur with the powdery substance.

Twilight looked down at her rump and nodded seeing not a speck of purple fur through the thick film of white powder. Nodding in approval, she threw her perfect straight black and pink striped mane from her face that came down her shoulders and gulped with a nervous expression as she lifted a giant white diaper over her head. The padding was big and thick with a big giant baby silver moon printed on the back of the diaper with little purple stars printed around the moon. The purple unicorn eyed it with suspicion and mumbled, “Moondancer said she wore these to help her study for the last test. Hopefully, she wasn’t just trying to embarase me.” She shuddered at the thought of one of her classmates seeing her in a diaper.

She then began to strap the diaper around her rump slowly unfolding the giant plastic square. Twilight then started to strap it around her backside slowly folding the front of the diaper over her belly. She then used her telekinesis to lower two straps onto the plastic landing zone with a dark blue field with little yellow stars printed on it. She smoothed the diaper out with a hoof and slid it around the baby blue leak guards that encircled her thighs to make sure the padding was snug. Twilight then slowly threaded her long purple and black striped tail through the back end of the diaper until popped out of the tail hole. She smiled at how the diaper was perfect around her rump and whispered, “alright now for the pajamas.”

Twilight lit her horn again as she hovered a set of giant purple footed pajamas. The fabric was covered in stars and swirling galaxies that made it look like something from a night sky. Twilight slowly slipped into the cute pajamas moving one leg at a time through each leg hole. She drifted her tail through the back tailhole then pulled up the zipper making sure it was perfect around her body. Twilight slowly rolled herself over and got onto all fours. She rose her body from the ground with the thickness of the diaper under her. The mare looked behind her and analyzed the massive diaper bulge and whispered, “I need to walk around and make sure it doesn't slip off or cause any issues while I’m studying.”

Twilight was getting used to it was added weight and decided to wiggle around the study. The padding was thick making her legs spread out and blushed seeing how exaggerated her waddle was. But the diaper itself shifted around her rump was tightly strapped around her bottom. Twilight satisfied with her test she continued with a smile, ”alright now I can start my studying.”

Twilight happily waddled to her seat and plopped down with a small poof of foal powder and a low wheeze made by the air escaping through the leg holes. A small blush rose on Twilight's cheeks as the mare slowly turned to see a cup of steaming coffee and slowly picked the cup up with her magic. Despite her caution the diaper crinkled with every small movement making the mare uneasy. But she continued to and slowly sip her drink despite the constant rustiling from the diaper. She placed the cup down on the small glass plate on the table still trying to get used to the embarrassing crinkles. Twilight then frantically picked up her books and a quill as she tried to forget about the foalish garment strapped around her and exclaimed, “alright time to hit the books!” She then began to analyze the open spell book and began to write notes down with her quill.

six hours later…

Twilight was deep into her studies and had a dozen scrolls jolted down with spells and complex puzzles. But, she has also drunk a couple of cups of coffee with three porcelain cups placed on top of each other as proof. Twilight was busy drinking the fourth cup looking over a scroll that she held within her magic, and she realized that the pressure in her bladder was starting to build within her. She groaned and scrunched her back legs into the thick padding. “No! I was hoping I wouldn’t have to actually use it.”

Twilight sighed looking at her fourth cup of coffee and slammed a hoof into her face. “Yet I was dumb enough to have four cups of coffee.”

Twilight unable to escape the pang of needing to pee she grumbled,” alright diaper you better do as the label proclaims or im getting a refund."

She started to let go of the pressure and sighed as she began to pee into padding. The mare blushes hearing the loud hissing noise that came from underneath her soft pajamas. But, the padding was thick and did its job in holding in the urine. Twilight out of curiosity prodded the diaper bulge within her footed pajamas making low squishing noises and gave a big sigh of relief, “it worked and did a swell job of keeping the urine in.” She giggled at the pun. “Swell job.” The mare laughed and kicked about in her soaked diaper making squelching noises. Twilight meeped from embarrassment and continued to flip through the pages of her spell book trying frantically to forget about the fact she just peed into a diaper.

five hours later…

It was still dark when the princess of Equestria woke up at about five in the morning. Celestia yawned as she stretched out her big white feathered wings and flung her long flowing colorful mane. She slowly stumbbled out of bed and mumbled, “hmm. Tomorrow is that big test, tons of papers to grade.”

She chuckled knowing her top student Twilight sparkle was probably staying up all night to study. Despite her telling the young mare time and time again that it was better to just get some rest. Celestia blushed realising how much the two have bonded since that young filly joined her school. Then her alarm clock ringed and she slammed a hoof down on it and growled as she walked her way to the bathroom. As the princess brushed her teeth and fixed her mane she looked into the bathroom mirror at her tired face and droopy eyelids. Celestia shook her head still wondering why she woke up so early. The princess still had an hour before she needed to raise the sun. Celestia turned to her window and whispered, “I wonder...should I check on Twilight?"

She then unfurled her wings and threw herself into the night. She flew through the air scanning the houses and found Twilight’s tower at the edge of the city. Celestia smiled and dived down towards it and gazed into one of the windows. She gasped upon seeing Twilight Sparkle. She was zonked out on in her study with a bunch of books scattered over the desk and the piles of notes stacked near her with the ink pot spilled over making a puddle of a thick black goo on the floor. But what caught Celestia's eyes, even more, was the cute footed pajamas Twilight wore with a big diaper bulge that shown through the fabric. The princess sighed shaking her head. “Silly mare what are you doing wearing diapers. Wouldn’t changing them take more time than just using the bathroom?”

She opened the window slowly and flew over Twilight. The princess smirked as she lifted Twilight within an aurora of magic seeing how the diaper sagged from underneath the pajamas. from the chair and laid down on the pink changing mat still set up in the middle of the room. Celestia slowly unzipped the pajamas down the middle and couldn't help but snicker as she unveiled the huge thick yellow stained padding with fading purple stars on the front. Celestia gave it a few taps hearing it squish under her hoof and scoffed. "You did a number on this diaper soggy butt."

She then slowly unstrapped the diaper and hummed as she took out some foal wipes and began to clean the filly’s groin area.

The purple mare still fast asleep murmured, “m..mommy wh..why..why are you changing me?”

Celestia giggled at the remark and played along as she cooed, “I knew you would be staying up late tonight for that big test later this afternoon. I was just going to come by to make sure you get some sleep.”

Twilight continued with a dreamy smile, “ I’m. I’m sorry mommy I wet the bed,”

Celestia paused realizing that Twilight was still deep in her sleep and continued the role as her mom and cooed, ”now Twilight, I don’t mind you wetting the bed. Now, how about after your diaper change I tuck you in and read a storybook.”

Twilight gave a tired no and whispered, ”yes mommy I would like that.”

Celestia with her gentle smile whispered, “alright well just hold still sweetheart.” She uncapped the foal powder in a blue aura and drifted over Twilight’s rump and started to powder it thoroughly until her rump was completely covered in the white substance again. Twilight seemed unaware as she stirred, “mmm...I’m here for the test mommy.”

The princess smirked thinking of a way to play along and continued, “yes now can you sing your ABCs?”

Twilight whispered under her breath. “ABCs...A is for Anthropomorphic...B is for Biomass...C is for Cellular reconstruction...”

Celestia dawwed under her breath and pulled out another one of the big thick diapers. She couldn't help but smirk seeing the big silvery moon on the seat of the diaper. She shook her head and chuckled, “I'm betting Moondancer got these for you huh? I remember her saying something about wearing diapers to help her study. I thought it was a joke.”

The princess just slowly lifted Twilight’s legs with her blue aura and slipped the diaper underneath the mare's rump and watched as. it sank into the padding. She then slowly slipped Twilight's tail through the tail hole and cooed, “that’s right good job sweetheart now can you count to three?”

Twilight kicked about on her fresh padding making it crinkle and murmured, “one short sparkle...two shots of lightning...three drops of liquid nitrogen.”

Celestia giggled and finished strapping the tabs over the diaper’s tabs on the landing zones. She rubbed a hoof down the soft diaper hearing it crinkle she felt a warmth in her chest where she knew deep in her heart she always wanted a foal but never had the time to care for one. Celestia then zipped the pajamas up carefully making an as little sound as possible. She lit her horn and slowly levitated Twilight off the ground as a cacophony of crinkles made from the fresh diaper echoed throughout the room. Celestia then slowly tip-hoofed up some steps to her student's bedroom. There she found a basket with Twilight’s baby dragon Spike sleeping soundly curled up in a ball as his tail was popped in his mouth sucking away on it. The princess smiled a little and whispered, “looks like we have two babies.”

Celestia continued tucking Twilight underneath the sheets of her bed. Twilight stirred and whimpered, “Mommy...I...I'm wearing a diaper..”

Celestia paused again and with a smirk answered in her motherly tone, “it’s okay diapers are okay to wear at school.”

Twilight paused seeming to think about what Celestia just said. The mare seemed to have clamed down as she whispered, “okay mama, can you read me a story now?”

The princess nodded “once upon a time there was a little unicorn who studied really hard, But she also liked to wear diapers. One day she accidentally went to school in her diapers and was laughed at it. But the teacher told her students not to laugh and brought the little filly to the front of the class to show how brave she was. Instead of laughing the class cheered and they all got As.”

Twilight stopped fidgeting and mumbled, “thanks mommy.” Celestia just gave Twilight a sweet smile as she drifted the blankets around her student's neck and kissed her on the cheek. “Goodnight and sweet dreams Twilight.”

She then adjusted her alarm clock by the bed setting it about around ten A.M giving her enough sleep and more than enough time to get ready for the test at noon. The princess took one last look at her student all tucked under the blankets with the diaper bulge still showing through. The princess couldn't help and coo, “all the little filly is missing is a pacifier.”

The princess lit her horn and a cute pacifier popped in Twilight’s mouth with the sun rays printed on the mouth guard. Twilight unconsciously gave it a few suckles and soon it started to bob up and down naturally. Celestia smirked and took out a small camera and snapped some photos. “Oh, I'm going to keep these forever!” The princess then stepped towards the window and flew through and into the night.

Chapter Two: Life Ruined, Check!

Twilight woke up the next morning to a ringing to her ears. She slammed a hoof down onto the alarm clock that screaming next to her bed. She yawned as she slowly got out of bed until the mare noticed she was wearing her dark blue nightie. Twilight squeaked in surprise at first kicking about hearing the diaper under her rump crinkle. The mare blinked with an odd look on her face and murmured, “weird, I remember peeing in my diaper last night…”

The purple-coated unicorn slowly unzipped her nightie with her magic taking it off as she looked down at the pristine white diaper (with the purple stars wetness indicators still printed on the front of the diaper showing she hadn’t peed) strapped securely around her rump. Twilight jumped out of bed with a look of astonishment and shouted, “how did that happen! I mean I was studying, and I soaked myself last night. So how is there a new diaper around my rump!?”

The mare turned to see her assistant baby dragon Spike walk into the room with his mouth wide open. Twilight squeaked as she shoved a hoof over the front of her diaper making it crinkle loudly. Spike still just rubbed his eyes in disbelief and asked, “so...a...are you…”

Twilight who was now super embarrassed as she looked up and asked, ”Spike...did you change my diaper last night?”

Spike couldn’t help but burst into laughter. “No of course not! Anyways why are you wearing that!”

Twilight stomped a hoof to the ground and growled, “like as if I’m going to explain that to you! Now, are you going to help me or not!”

Spike shrugged as he walked over and tried un-taping the tabs himself around the front of Twilight’s diaper, but they seemed unable to budge. The mare shouted in horror. “Why can’t it come off!”

The mare tried pulling the tabs off with her magic and saw that nothing she did could get them off. Twilight Spark shouted, “how could this happen!” She groaned and tore out her mane as she was getting becoming more worried about being late to her test. Twilight looked across the room at her alarm clock and saw that she now had exactly one hour and thirty minutes left. She turned around towards her young dragon assistant and out of desperation, she shouted to Spike. ”Light it on fire!”

Spike squeaked with surprise and stammered, “a..a...are you sure?”

Twilight with her eye twitching shouted, ”yes please light it on fire!”

Spike gulped as he readied himself taking in a deep breath and in one swift motion the young dragon burped out a massive burst of flame lighting the diaper on fire. The diaper burst into flames making Twilight squeak stumbling backwards as the flames disappeared into a cloud of smoke. Twilight saw that the diaper was utterly unscathed as she shouted, “what! How could this happen!”

Twilight got off the bed and ran over to the package of diapers and turned it around reading the label. Warning: after eight hours this diaper can only be taken off by the one who placed them on just in case to keep the diaper from opening by another pony or by accident. After twenty-four hours the diaper will remove itself if no one else does so or one hour after an accident.

The purple unicorn groaned seeing down below. “These diapers are magic and fireproof buck!”

She threw the package of diapers at the wall as the neatly folded diapers exploded out from the plastic and flew all over the room. Spike turned around and asked, “was there any pony else who you had over last night?”

Twilight crossed her forelegs with a cute pout and scoffed, ”of course not! Nopony would have changed my diaper! But it doesn't matter the test is happening in two hours!”

The mare groaned as Spike shrugged and asked, “why don't you create an invisibility spell.”

Twilight looked down at the empty plastic that was on the ground. She saw something else on the package and read it. If you find yourself needing to have the diaper not be noticed it has an invisibility spell attached warning: The spell isn’t fully ready as these diapers are prototypes. Please Understand that means the padding will still be noisy and will always be around your rump.

Twilight was a bit astonished at what she read. “These diapers are weird…” But Twilight plopped onto her rump making it crinkle and looked down at the diaper around her rump and asked, ”um diaper turn invisible please.”

The padding instantly seemed to have disappeared making it look nothing was there. Twilight gave another walk around her room and groaned again hearing the padding crinkle and saw she still had an exaggerated waddle. Twilight couldn’t help but stomp a hoof with agitation and roared, “it’s invisible! But it still makes noise, and I look like something is up my rump!”

Twilight continued to waddle about for a little longer and squeaked as she accidentally hit Spike with the weight of her diaper sending him flying as he giggled, ”wow be careful with that rump.”

The purple mare turned around at Spike with an angry glare as she shouted, ”instead of making fun of me how about help me think of a way to make me have a good excuse for this crinkling and to make sure my diaper doesn’t hit other ponies!” This made the young dragon stepped back with a sheepish smile still unable to contain the fact. Twilight the earnest student of celestia looked like a padded toddler having a temper tantrum.

The baby dragon tapped a claw to his chin and asked, “so what about we also make you wear a dress or a skirt? That will make it easier to see as the fabric will be around the diaper, and it’ll make an excuse for the rustling.”

Twilight beamed a smile and bounced over hugging Spike as she squealed with delight, ”that’s a great idea Spike!”

She scurried over to her closet and picked out an old school filly’s uniform. It was cute with a white vest and a blue overcoat and a dark blue tie. Twilight quickly dressed then took a big blue skirt and with her magic and slowly placed it over her rump. The skirt had ruffles which spread out of her backend forming around the padding. Twilight gave a relieved smile and exclaimed, “it works Spike awesome job!”

Twilight then looked around at the clock and saw that she only had thirty minutes and squeaked, “oh dear Celestia! I’m going to be late!” She then burst from the room and down the hall and out into the streets of Canterlot.

At Celestia’s academy for gifted young unicorns. The princess was standing at the front of the classroom looking over her students with a look of fear and nervousness. Everyone of her students sat straight up and ready for the test. But it seemed that there was only one desk missing and blushed seeing Twilight wasn’t among the class. The princess continued looking for Twilight and sighed, “oh dear did she wake up?”

But she sighed in relief as Twilight burst through the doors in the back of the room wearing a cute school uniform despite the fact they didn't need to wear one today. But Celestia shrugged and just watched as her favorite student waddled to her se...waddled? The princess blinked seeing Twilight waddling into the classroom with something seeming to bump into her students. The young mare squeaked out apologizes appearing to be quite nervous and aware that something wasn’t right. Twilight gulped as she sat on to her chair making it fly up and crinkle as the mare blushed hard trying to brush the skirt down. Celestia shrugged assuming it was the skirt and started handing out papers for the test. The princess continued to instruct her students. “Now you all know the rules for the final exam of the school year. Everypony must have their test finished and have every answer filled out before you can leave the room, that also includes bathroom breaks.”

Twilight's ears went behind her head when she heard that and squeaked as Celestia made sure each student had a test in front of them. Once every test was handed out Princess Celestia walked up to her front desk and looked back at her students and exclaimed, “now, unless you have any questions, begin!”

At that everypony started their test and Celestia watched closely seeing that Twilight was nervous the entire time. But shrugged as she knew the mare had a bad case of test anxiety. Celestia watched as she seemed to shift about and gulped and saw sweat pouring down her face. The princess then heard more rustling and crinkling, and it all hit Celestia like a truck… Twilight is still wearing a diaper!

The princess was now nervously sweating unsure of what to do. Despite she and Twilight having a relationship, the princess couldn’t just have the mare leave the class knowing it would be an automatic failure. But what was going through her mind was why she would keep a diaper on? Did something happened when she changed Twilight last night?”

Twilight continued to write down the test answers, but Celestia noticed the mare ‘s face was flushed red as she kicked about looking queasy. The princess blushed and could only hope Twilight can hold her pee in. But she gasped seeing Twilight looking around with a nervous whimper as a queer hissing sound flooded the room.

Everypony looked up and around but trying to figure out where the odd sound was coming from as Twilight’s ears drooped and she bent down to look at her test shaking all over. Celestia instantly exclaimed, ”oh uh don’t worry about that it’s the pipes. They are quite old as you know.”

Most of the students shrugged at the answer and Twilight looked up at Celestia with a relieved smile on her face and continued to finish the test with a slight blush. Celestia sat back at her desk waiting patiently hoping that she could take Twilight somewhere private to get the diaper off her rump.

As each student slowly finished their tests and placed them on Celestia’s desk. Twilight waddled up to the desk with her face now a deep red as an odd squelch came from her. Celestia waited patiently as Twilight got to her desk and asked, ”hello Twilight I’m guessing another hundred?”

The purple unicorn gave a nod and exclaimed, “yep! As you can see every question is visible.”

As she placed the test down the diaper suddenly appeared around Twilight’s rump with the silvery crescent moon printed on her rump. The rest of the class gasped and giggled seeing Twilight Celestia’s favourite student was now showing off her thick diaper now slightly stained yellow in front of all of them. The embarrassed student turned around feeling the burning gazes of dozens of ponies and looked down at the diaper, with its thick padding with the cute purple fading stars now revealed itself to the world. Twilight was speechless quivering with anxiety unsure of what to say or do being too embarrassed to say or anything. Celestia with a sudden thought coming to her mind she got up quickly and exclaimed dramatically, ”oh wow Twilight is that apart of your final project due tomorrow!”

Twilight gulped as she pressed her legs together making her diaper squelch as she stammered, “y...y...yeah! I um...uh was studying the..um chemical compound Sodium Polyacrylate which is most common absorbent material in foal diapers!”

The class was a bit stunned as Twilight still shaking with her diaper crinkling the mare continued the silly lie. “Yes, and I was studying the science of diapers last night and well...I forgot about my experiment...so um...yeah!”

Many of the class applauded with smirks on their faces. Celestia got up and squeaked,”now, if you excuse us I need to talk to Twilight about her odd project.” The princess then scurried her student out of the room as Twilight waddled away as quickly as possible with her diaper squelching as she cried, “my life is ruined!”

Back in Celestia's study at the academy Twilight was lying down on her back in front of the princess. Celestia legs up in the air with an angry look on her face as Twilight already told her all about the diaper and it’s magic. The princess gulped as she was getting out a stash of adult foal supplies she conjured up and whispered,”I’m...so sorry Twilight if I knew that about the diapers I would have never changed you last night.”

Twilight was now the one embarrassed as she looked squarely at the princess and exclaimed, “you were the one who changed me last night!”

Celestia with a light blush squeaked, ”yes...I couldn’t just leave you in a soaked diaper…” The mare then slowly untapped the tabs from the diaper. Twilight just looked back up at the ceiling and complained, “well what do I have to do now? My whole project was on Starswirl the Bearded! Not bucking diapers!”

Princess Celestia continued to clean the mare’s rump carefully with foal wipes. The princess watched as Twilight fidgeted about with the wipes being quite cold; then, slowly slid the sodden diaper from her student’s rump as she explained, ”well considering the circumstances and that this whole thing is partly my fault. I think I’ll help you with the project.”

Twilight was stunned unable to even shiver at the cold touch of the wipes as her heart stopped in her chest. Studying with Princess Celestia? It was a dream come true! Despite the fact it would be about stupid diapers it didn’t sound too bad. She sighed, “yeah I don’t see any issues with that.”

Celestia gave a nod as she took out the foal powder and started to sprinkle Twilight’s rump and nether regions. The unicorn was a bit confused but could only sneeze as Celestia was making sure Twilight's rump was now completely powdered white. The princess of the sun cooed, “that’s wonderful to hear, we’re going to make an excellent team.” She balled up the sodden diaper carefully; and, threw it in in a pail then began taking out another diaper with her magic. This padding had her sun cutie mark printed on the seat of the diaper and she was unfolding the plastic square. Twilight watched with a horrified look and exclaimed, "Wait, Stop!”

Celestia stopped in her tracks as she saw blinked in astonishment and quickly threw it aside and apologized with a slight blush. “Sorry, guess um...I got carried away.”

Twilight slowly got up and shook her rump trying to get the powder off as she whispered, ”look, I’ll go back to my place and take a shower...” Celestia nodded and added,”I’ll go through the royal library and find books on Sodium polyacetate. But um...just stay at your place I’ll meet you there in secret.”

The student gave a nod and quickly burst through the doors and galloped full speed to her tower. Celestia looked down at the adult diaper with the sun printed on it and pondered on the reasoning behind wanting to diaper her favorite student.

Chapter three: Celestia is crazy, Check!

Twilight was now in Celestia’s chamber reading a giant book on the science of diapers. The princess herself was laying lazily on the bed reading a large book about the history of diapers. Twilight had her eyes aglow with the childish wonder and she shouted, “Can you believe the Sodium polyacrylate, also known as waterlock, is a sodium salt of polyacrylic acid with the chemical formulaₙ and this superabsorbent polymer has the ability to absorb as much as one hundred to one thousand times its mass in water. Sodium polyacrylate is an anionic polyelectrolyte with negatively charged carboxylic groups in the main chain. While sodium neutralized polyacrylic acids are the most common form used in the diaper industry! I bet we could design even better diapers if we can somehow define the absorption rate then maybe create wetness indicators designed to show the parent how soaked their foals diapers are.”

Princess Celestia just gave a chuckle as she was unsure of feeling a hint of love just seeing Twilight looking excited about the odd subject. She gave a nod and cooed, “Yes, that does sound good, but we would need to test your diapers...”

Twilight gave a deep blush having a feeling that Celestia wants to diaper her again. The mare waved a hoof. “Oh, I’m not wearing another diaper. I’ll just use an ammonia base yellow liquid to look like urine to fill the diapers for the experiments.”

The princess of the sun shut the history book and commented, “Yes, but as the great doctor Paddington back in the classical era created his new compound he tested the first diaper himself. I think we should honor his research.”

Twilight gave a blush as she explained, “Well, it’s embarrassing. I mean I don’t ever want to be caught wearing a diaper again.”

The princess threw the book aside and explained, “I mean you already were, and...I’ll designed it with you. Please, it will be fun!”

Twilight was unsure about this despite Celestia being her mentor and seemingly seems to be genuinely happy from experience. The young unicorn mare didn’t want to ruin the princess's fun and sighed as she gave a nod. “Well alright, I think that it’ll be fine, but I…I'm not peeing in front of the class. We can show the class the experimental diapers we designed.”

Celestia looked down a little disappointed and gave an exasperated sigh, “right…well, we may need some supplies to start.”

The princess then lit her horn and a pile of stuffing and white plastic poofed into the room. Twilight was stunned and asked, “Celestia...where did all these diapers come from?”

Celestia blushed a little as she continued to explain, “I…I had practice creating diapers in my spare time. You just work on the science and measurements to make sure we're doing this right?”

Twilight gave a nod as she turned towards her task of measuring formulas and chemicals blushing as she thought to herself, Why does Celestia want to diaper me so severely?

The two mares worked all night and there in front of the two there were two diapers one with lines indicating the amount of liquid it will expand with, 25 ML. 50, ML. 75 ML. While the other plastic square had a huge smiling sun on the front. Twilight’s face was flushed red as she lifted the foalish padding in her magic. Twilight looked upon the diaper with disdain and groaned, “As much as I agree that this diaper reflects the exact measurements to a perfect diaper, I’m not sure about this design.”

Celestia turned around with a loving smile and cooed, “But…um…it has to be foalish as it…um reflects its intended purpose right?”

Twilight looked over at Celestia who was giving her a sheepish smile. “Well, I guess….seems like we did all that’s needed for the project I should get some rest.”

The princess nodded and looked outside. “Its night right now, maybe you should just sleep here with me….diapered…”

Twilight paused as she looked up at the princess who was seemingly scared of the answer and the young student was unsure of what to do. She turned around and asked, “Well um…I wouldn’t mind…but I have to ask why you want to diaper me so much?”

Princess Celestia paused unsure of how to respond as she continued to explain with a blush on her cheeks.“Well, if I tell you to promise not to laugh.”

Twilight gave a nod “I promise not to laugh.” The princess of the sun paused and quivered in front of her student before she continued to explain, “Yes, I see you as my daughter and I really just want to treat you like a foal. I know that sounds silly but you worked so hard, and I always thought it would be great for you to relax.”

Twilight turned around with a blush on her face and sighed, “Well, maybe I guess that will be alright if you diapered me tonight. But let’s not wear the diapers we prepared for the presentation I don’t want to ruin them.”

Celestia took out the package of unused diapers that looked exactly like the ones Twilight wore the night previously. The mare was nervous, but she let Celestia powder her rump nicely with white foal powder. The princess then strapped her student up in a thick blue diaper. With the cute little stars printed over the diaper and the crescent moon printed on the seat of the diaper. The princess then began pulling the diaper over her student's seat with the diaper rustling and crinkling, the princess slowly strapped the plastic tabs over the landing zone decorated like a night sky.

Twilight was beyond embarrassed at the fact the princess of Equestria has diapered her for a second time but was still unsure if she should say anything. Before the mare could protest, The princess slipped the filly up into a dark blue sleeper and slowly zipped the long zipper over the mare's body. Twilight was beyond embarrassed seeing her diaper bulge showing through the foalish sleeper once again. Celestia just looked down with a motherly smile as she patted the diaper with a hoof loving the sound of the diaper crinkling underneath and cooed “you are the most adorable filly in the world.”

Celestia then bent down and kissed the mare on the forehead as Twilight was too embarrassed and just gulped. The princess then lifted her student with magic and slowly tucked her under the covers and tucked them under her chin. The princess then came over and slowly tucked herself under the bed with her student as she folded her large white wings over her student. As they drifted off to sleep, Twilight just looked up at the ceiling completely confused and a bit unnerved by all of this as she thought to herself, Why is Celestia so obsessed with putting me in a diaper.

Later that morning Twilight was mare gulped as she was nervous in her seat watching as many of the students did their end of the year projects. They were about various spells and scientific discoveries as that was the sole purpose of these projects. Twilight gulped as she scrunched her diaper with her front hooves and waited patiently with a sheepish smile on her face. As she turned to see that Celestia who gave a nod as the mare slowly got up and many of the classmates giggled seeing Twilight slowly waddled to the front of the class. The mare cringed seeing her legs so spread apart by the diaper and with it rustling and crinkling with each step. The big poofy diaper smacked into other students as she waddled across the room. The classmates were giggling and snickering unable to comprehend the fact that Twilight, the most studious pony ever was waddling about in a thick diaper like a little filly. The mare was now in front of the class fully diapered again with a big smiling sun printed right on the seat of rump and exclaimed, “I know, this is weird! But diapers are interesting, and there are weird but hear me out. Only fifty years ago plastic disposable diapers didn’t exist. Imagine raising foals with just simple cloth diapers all the time. It would be a nightmare.”

Many of the students blushed and whispered amongst themselves Twilight continued, “that was the state of things, and with the population boom the need for taking care of foals was becoming something that Equestria needed. So a doctor name Paddington was thinking of a way to create a Superabsorbent polymer (also called slush powder) which can absorb and retain vast amounts of a liquid relative to their own mass. So Paddington went about combining Chemicals in his lab to create a compound that can effectively absorb urine than what they had out in the market at the time. The mare then presented the test diaper all folded up in a perfect square. This diaper was designed with lines with 25 ML, 75 ML, and 100 ML underneath that. She placed down the diaper on a pedestal and took out a beaker full of fake urine and explained, “You see as I pour this sample of fake urine into the diaper I’ll show how it absorbs and expands.”

As she started to pour the beaker of yellow liquid onto the padding and watched it rise as the lines of 25 ML, to 50 ML began to disappear. The whole class listened as she continued to pour and explained. “you see the fabric will absorb the urine and for most wetness indicators will disappear as the pee makes the diaper swell. I got the approximate measurement to absorb it without delay, and in that case, we can identify when the compound can no longer hold together.”

As the mare finished pouring the fake urine, the 100 ML faded as a big red stop sign appeared on the diaper. The class was impressed and stunned then Twilight turned to show a chart near the podium with suns on the top was a giant sun with a smiling sun, as it slowly faded under the clouds down to the bottom where it was slowly hidden by clouds blaring orange like a sunset. Twilight then continued to explain, “This is what we like to call smart wetness indicators, mostly they’re magical and the sun indicated will set as the diaper is being soaked until it reaches its limit.”

Some students chuckled, but they were most impressed as Twilight continued her project. “It was on accident when he poured a bottle of crushed pure sodium onto polyacrylate and saw it expand upwards. Then the stallion tested and studied the compound and saw that the padding rose up. It can absorb liquids quite well. We learned to map out the absorption level of the compound and to use a catalyst that will indicate wetness. We can use it to create diapers that can do a better job with an indication of how much it can absorb.”

Twilight then turned around to show off the back of her diaper that she was wearing with the big cute smiling sun printed on the seat. Then all of a sudden a hissing sound echoed through the room like the back of the diaper began to soak yellow. Twilight squeaked in horror not releasing what’s going on before she felt the hot liquid filling her diaper making her whimper. The class burst into laughter, but they watched as the sun on the front of the diaper set as Twilight whimpered, “the idea is that the sun will continue to fade as the diaper is soaked with liquid.”

Many students murmured and some mares who were new parents gave nods of approval seeing how the diaper was well designed. Despite the foalish garment being around a grown mare.

As Twilight poured a loud hissing noise came from somewhere, but it was masked by the mare finishing spilling the beaker of fake pee on the diaper. When finished she noticed that many of the classmates were giggling and pointing at her and snickering. Twilight froze in place as she started to pee some more. The noise hissed, and the mare squeaked as her diaper swelled and soaked the front of the diaper. The sun was now slowly setting under a cloud as the white padding yellowed and she blushed hard seeing how cute the sun which was quite adorable. But she felt strange wondering how she was peeing in her diaper. Then it dawned on Twilight who turned to see Celestia standing by with her horn lit with magic she suddenly stopped and looked away as Twilight gave her an ominous glare. The mare then turned to the class and sighed, ”yes, as I peed some more into my diaper. The wetness indicator changed to that of a sun hiding behind the clouds, that shows that I’m quite soaked and I need a change.”

The class dawwed and chuckled some more as Twilight waddled over craning as her diaper squelched between her legs. She then took out the final part of her project which was a couple of packages of foal diapers. “I know we had some mothers in the room and I would like you to try these for free on your own foals.”

The whole class clapped with approval as Celestia joined with the applause and cooed, “That was quite the adorable and amazing project never in my thousand years have I saw a project on such an odd subject do so well, you earn an A+! Just stunning” Just as the motherly mares got up and began taking the free samples. One mare came over and whispered, “Um…do you want me to change you? I have twins of my own, and I’m very skilled.”

Twilight shook her head and sighed, “No it’s okay, I’ll do it myself later.” She turned towards the princess who gave her a reassuring smile. But the mare was a little concerned, as she thought to herself. I’m happy Celestia is happy, but she made me pee my diaper in front of the entire class?! Seriously why does she want treat me like a foal so badly!”

Back in Celestia’s room the princess once again had twilight on the carpet as she was busy changing the soggy diaper now laid out before with Twilight laid down just looking up at the ceiling. The mare was silent and seemed to be flustered after the embarrassing project was finished. Celestia hummed a sweet tune as she continued to wipe the mare’s crotch down with foal and cooed, ”you did a wonderful job, in fact, we should sell the diapers to a company. I wouldn’t mind having a brand named after me.”

Twilight rolled her eyes and grumbled, “look, I rather we put this whole thing behind us okay? I know…you wanted to do this and all. But that was really embarrassing.”

The princess gave her student and apologetic look as she explained, “I’m sorry, but we need to see it just to make sure they worked.”

Twilight just shook her head still angry at the princess, as soon as Celestia balled up the sodden diaper and tossed it in a pail. The angry purple mare got up and grumbled. “Well at least you had fun, but right now I just want to take a shower.”

Celestia turned around and tried to reassure her student. “Oh don’t be so angry Twilight. Everypony is graduating this year there will be jokes, but you really blew the project out of the water in less than a day. Most ponies in your situation would have crumbled under stress.”

Twilight who was furious after what Celestia did and finally exploded, “You’re the one who got me into this mess in the first place! I mean honestly stop trying to act like this is going to blow over! You could’ve ruined everything for me and made me the laughing stock of Canterlot!”

The princess was stunned and but looked down to the ground knowing that Twilight had a point. The mare paused seeing how to hurt Celestia was and feeling guilty she whispered, “look...I...”

Before she could say anything, else Celestia just whispered. ”You can take a shower after that we can forget about this.” The princess then slowly walked through the door as Twilight shouted in frustration and stomped toward the shower.

Chapter four: Pamper Payback, check!

A year later….

It's been over a year since Twilight Sparkle came to Ponyville and she was busy pushing a shopping cart down the superstore aisle as she was preparing to send some gifts over to Mrs. Cake for her new babies as she just learned the Cakes are having twins. She already loaded her shopping cart with foal stuff. The mare had everything from toys, to clothes. The last items the mare was grabbing were the diaper care items with foal powder, goal cream, wipes, and a diaper genie all in her cart. The last aisle was the embarrassing diaper aisle. (Which Twilight dreaded going down remembering the last time she was near these things) Twilight blushed as she slowly poked her head down the aisle seeing the rows, and rows of foal diapers packaged tightly in plastic of all kinds for almost all ages. After a few heavy breaths, she slowly pushed her cart down the aisle looking left and right for diapers designed for Newborns. The mare suddenly froze in front of a few packages of diapers as her mouth dropped wide open. The packages were bright yellow, and on the yellow plastic, It was labeled in big white bubble letters. “Little Sunshine” The diapers looked precisely like the padding she crafted back when she was living in Canterlot. Twilight took the package with her magic to examine it better and saw that it had Celestia’s face plastered on the packaging with a little circle of words around her mug reading, Celestia approves the quality of this product.

Twilight was just stunned with heart in her chest beating rapidly turning the package over reading the various ingredients that are on the diapers. Then at the bottom under all that was. This design created by Mrs. Paddington. Twilight blinked with surprise, “Paddington...you mean she’s the daughter of thee Doctor Paddington!?”

Twilight turned around and lit her horn with magic spilling a dozen packages of the same brand and quickly rushed out of the aisle as fast as she could.

The instant Twilight was back in the library Spike came around the corner to greet Twilight and asked, ”hey you got the gi-?” The young dragon gaped upon what he saw Twilight stood just before the door with a half dozen package of diapers all around her and Spike with a stunned look squeaked, ”holy Celestia you didn’t need to buy so many diapers!”

Twilight looked around with an embarrassed look and gave an exasperated sighed, ”I didn’t buy them just for the baby shower. Look, these are the same diapers Celestia had me wear for my final project remeb-”

Spike blinked with surprise expression still on his face unsure of what Twilight was talking about. The mare then waved a hoof and tried to brush the issue off casually. “You know what on second thought I’ll just go upstairs.” The mare then took one of the packages within her magic and quickly ran up the stairs as fast as she possibly could. When she reached her study Twilight instantly got out a pen and a scroll. “Dear Princess Celestia, did you sell the idea of the diapers I created for my final project a year ago? Please respond ASAP!”

Twilight then quickly rolled the scroll up and shouted, “Spike come in here!”

The little dragon ran upstairs and asked, “what’s going on! Seriously! Is this about that time you had a diaper stuck to your rump?”

The mare was beyond irritable and stomped a hoof on the ground and shouted, “just send this to Princess Celestia right now!”

She then shot fire at the scroll and sent it to Celestia, and in a few minutes, a scroll poofed right into his claws. The dragon then began to read from the manuscript,

Dear Twilight,

Yes, I gave the idea to a Mrs. Paddington she loves making diapers and makes the best in Eauestria. So I gave them your designs, and she loved them and made some adjustments, but overall it’s your design. If you wish there is a substantial bit Mrs. Paddington has set aside for you for the model as well. I didn’t input your name on the packaging as I was unsure if you wanted any relation to this. In any case, let me know what you want. To do?

Sincerely Princess Celestia

Twilight scratched her chin and whispered, “yeah, I don’t see anything wrong. But, do you think they properly tested these?”

Spike scratched his head as he responded, “Yeah I think they probably would have before sending them out.”

The mare then slowly and carefully opened the package of diapers with her magic peeling off the yellow plastic and taking one of the perfectly folded squares from the packaging. She revealed it before herself seeing the bright sun sitting on the seat of the diaper. Twilight then had an excellent idea pop into her head. “Oh, I know what I’m going to do! Spike send a message back.”

Spike then took out a scroll and quill as he prepared to write and asked, “what would you like to say?”

Twilight trotted back and forth across the room then she raised a hoof and exclaimed, “I know!”

Spike then began to write as Twilight continued to talk,

Dear Princess Celestia,

I thank you for the proposal, and I’m fine with Mrs. Paddington using the design to her liking and I would like to instead use the bits I earned from the “foal care” industry as a way to pay for the school here in Ponyville in help funding for a new playground. As for any inputs on the diapers themselves I would like to run some tests with you to see for myself that they are working correctly. I have finished my friendship lesson earlier this week and wouldn’t mind coming this Friday afternoon to test the diapers. If this is inconvenient, then let’s reschedule for next week.

From your faithful student

Twilight Sparkle

Spike finished writing the letter and sealed it before bursting it into flames and sending it magically to Princess Celestia. Twilight then nervously began to tap a hoof awaiting for the princess’s response when a letter suddenly appeared out of Spike’s mouth. The young dragon broke the seal and read it.

Dear Twilight

I accept the proposal and will be waiting for your arrival at my palace tomorrow afternoon.

Twilight rubbed her hooves together with a cunning smile on her face, “Oh Celestia wait until I show what I have in store for you.” She then laughed maniacally with Spike just scratching his head completely confused on what’s going on.

The next day

Twilight was now back in Celestia’s room with the princess looking nervous they haven’t spoken in person since The Galloping Gala, and even then they didn’t mention “the diaper incident.” Twilight stood before her mentor looking down with a guilty expression seeing that she never properly gave the princess an apology for what she said to her. Princess Celestia gulped as she steadied herself and began to explain, “look I know that, we haven't really discussed the diaper incident since it happened and before we start I want to know I apologize for my behavior.”

Twilight gave a slight nod as she whispered, ”I also apologize, I know that you can't have children of your own. After you explained how you saw me as your daughter and wanting to diaper me makes sense.”

Celestia looked down at the ground as she sighed after the “diaper incident” The princess took another test from a doctor and learned she was still infertile and probably will never be. But the princess shook her head wanting to avoid those dark thoughts and with a light smile asked, “alright, how about we get past the drama and get right into why your here?”

Twilight smirked at her mentor and with a sly smile cooed, “oh you think I was going to test the diapers, nope despite the fact I forgive you for diapering me. I think it’s about time you get a taste of your own medicine.”

The purple-coated unicorn took out a giant-sized version of the infant diaper she had back at her library. Twilight laid the plastic object out before Celestia who looked down with a blush. The princess's face flushed red as she understood exactly what her most faithful student wanted her to do and gave an exasperated sighed, “well it is only fair…”

The princess then laid down on her back and spreading out her back legs. Twilight stood before her mentor as she slowly shook some foal powder on her mentor's rump rubbing the white powder into Celestia's white fur. Celestia couldn’t help but kick a little and sneeze as some of the powder hit her nose. Twilight gave a small chuckle as she then slowly lifted Celestia’s rump and slid the diaper under. She then slowly laid her mentor's rear onto the plush innards off the diaper making Celestia whimper at how soft the diaper was and wiggled a little making the plastic crinkle quite loudly. Twilight snickered and continued to diaper her mentor’s rump as she used her magic to fold the top of the diaper over the mare’s plump rump and sealed the diaper tightly with the plastic tabs onto the sun designed landing zone making it crinkle. After finishing, Twilight looked down at Celestia with the thick white diaper blending with the alicorn’s coat making the happy smiling sun on her rump even more pronounced. What made twilight daww was the cute little yellow leak guards that lined the outside of the padding. Twilight gave the diaper a few pats and cooed, ”oh look at you Tia all padded up. Now come on let’s get you up.”

Celestia’s face was still flushed red too embarrassed to protest. As she got up the diaper’s padding spread out the alicorn’s legs with it seeming to form correctly around her thighs and rump. But what made Celestia squeak as Twilight rubbed a hoof around the yellow leak guards and asked: “it’s not to tight is it?”

Celestia fidgeted about making the diaper crinkle and rustle as she squeaked, “it feels comfortable.”

Twilight gave a nod as she took out a clipboard with her magic and quill and asked, “now can you walk around a little?”

The princess sighed, but she did as Twilight said and waddled about in her diaper. Celestia was still so embarrassed at the fact she had such an exaggerated waddle as the padding kept her legs spread apart, making crinkling noises with clouds of foal powder poofing out of the thighs of her diaper. Twilight snickered as she asked, “now as you walk does it like it’s too tight or too loose?”

Celestia shakes her head “no it feels fine no issues so far.”

Twilight checked marked something on her clipboard as she instructed, “Okay, next is the play test. I brought some foal toys I’ll expand to be bigger. You’ll play like a foal for thirty minutes just to see how durable these diapers are.”

The unicorn lit her horn as foam blocks, dolls and balls all poofed into the room as if from nowhere. Celestia was quite stunned as Twilight smirked, ”Alright I’ll start the timer in three...two...one...GO!”

Celestia sighed as she sat down and began to bounce a ball with her hooves looking irritated now. Twilight then came over and held out her hooves and asked, ”wana play catch?”

Celestia giggled as she threw the ball with her hooves Twilight caught it with her magic and threw it right back. They played for some time before they did a game of hide and go seek, tag, then they built towers together and when the timer finally beeped. Twilight came over to Celestia who was busy playing with some dolls as she ran a hoof around the diaper and checked it. Celestia squeaked out in surprise and whined, “warn me before you do that!”

Twilight gave her mentor a sheepish smile as she checked marked the next box and squeaked, “Okay I’ll keep that in mind, for the next test it's...for the wetness test…”

Celestia gulped as she knew this was eventually coming. The princess stood up and released what was in her bladder as it made a hissing noise. Celestia was silent as her diaper yellowed a little and the Sun began to hide behind some clouds on the back of the diaper. Twilight then checked marked something on her clipboard seeing no leaks and chirped, “good, now you play for thirty more minutes.”

Celestia stomped a hoof on the ground and whined, ”oh come on seriously?”

Twilight scoffed, ”you barely wet that diaper, and we need need to how durable these are even when used. I need you to pee some more during this play time as well.”

Celestia grumbled irritably but did as Twilight said, and they continued to play together for another thirty minutes. Despite the princess’s misgivings about this “testing” it was quite fun and thrilling to act like a foal Then Twilight looked down at her mentor's padding seeing the diaper was a little more soden but overall holding well. “Okay the diaper looks good, and it’s holding well. But now for one final test…”

Celestia stomped a hoof in defiance and shouted. “No...no way I’m not messing my diaper!”

Twilight blushed as she explained, ”look once you do this it’s done. I'm doing this just to make sure this product is faulty in any way. Imagine a parent having to deal with a diaper that doesn't work?”

Celestia groaned but conceded siding that her student did make some good points. She grunted and let out a giant mess into her diaper as it bulged and browned in the back. The once cheery yellow sun was now an angry orange sun with black thunder clouds surrounding it. Twilight gave a nod as she gave her clipboard a checkmark, ”good it holds, now let's get you out of that messy diaper.”

The princess grumbled as she laid down cringing feeling the mess in her diaper. Twilight came over and made quick work of the diaper change. Once finished with the messy diaper balled up and thrown away. Twilight looked down at Celestia with an apologetic look and asked, ”how do you feel?”

The princess got up seeing her rump nice and clean she squealed, “that was actually quite fun! I feel like a new princess! I need to do that more often!”

Twilight laughed, “well, don't make it a habit.” The purple unicorn then began to shrink the toys and other foal supplies and placed them in the bag. “Now, that the testing is complete, I guess we can give the results to Mrs. Paddington, and I'll make sure my bits get donated.”

Before she left Celestia flew in and gave her student a big hug using her wings to envelop Twilight in a feathery embrace. She then cooed, “thank you, that was fully quite fun. I'm happy we can find some common ground on this diaper business.”

Twilight still a little unsure whispered, “yeah but like I said we can diaper each other once in a while. But I rather this doesn't turn into a habit.”

Celestia gave a bod as she watched Twilight walk away. Then out of nowhere, Luna burst into the room. “Dear sister, I too wish for a diaper to be designed after me! It's not fair, there should be a nighttime diaper named after me too!

Celestia smirked as she answered, “well...you might need to do some testing first…”