It was another beautiful day in Ponyville as the sun shone brightly down on the residents below.
Ponies were bustling around, going about their business all around Ponyville.
Among the busy ponies were a white unicorn and a purple alicorn, whom everypony was quite familiar with.
It was none other than Twilight Sparkle, the Princess of friendship, and Shining Armor, Prince of the Crystal Empire.
It had been awhile since Shining Armor had come to Ponyville for a visit to see his sister, and he felt it was overdue.
Usually his wife Cadance and his daughter Flurry Heart would be with him, but it had been forever since the two siblings had spent one on one time with another.
It would be nice to just enjoy each other’s company for a few days and have fun doing things they loved doing with each other when they were younger.
Right now, the two were on their way to Sugarcube Corner for some dessert after lunch.
It was a bit slow going, as every couple yards or so a pony would stop them and ask for a picture or an autograph, but they were both happy to oblige, happy to make a pony’s day with such simple jesters.
Eventually the two made it to the sweet shop, eager to pick up some delicious treats. The two waited in line and bought their items, each going with an ice cream cone and settled in at a table to continue their conversation.
It was the middle of the afternoon rush for the small business and there were lots of ponies in line eager to buy treats of their own from the establishment.
The Cakes and their friend Pinkie Pie were doing their best to keep up with the demand while also keeping an eye on the Cake’s two young foals Pound and Pumpkin.
The two were in a playpen off to the side at the far end of the counter, with Pinkie or one of the Cakes stopping over now and again to make sure the twins were playing nice together.
The two foals played with their baby toys, occasionally looking up from their fun at the world outside their playpen to see if anything interesting was happening.
Needless to say, the foals had little interest in the line of ponies that happen to be waiting about for sweets, finding playing with their toys much more fun.
Across from the playpen was Shining and Twilight’s table, where the two continued to catch up and tell funny stories.
They were just finishing up their cones and getting ready to leave when they each felt a powerful blast of energy impact their bodies, pushing them and the chairs they were sitting on against the wall.
It only lasted a moment, but both practiced magic wielders knew it was a powerful amount of magic that had been blasted at them.
A quick scan of their surroundings found they were in no danger, and the two quickly deduced based on the exhausted looking unicorn foal laying down in the playpen it had been a magical outburst from her.
It was very common for baby unicorns to play with their magic, but since they were so young and inexperienced any over exhaustion of their horn could cause the magic to fly uncontrolled outward into anything that was in front of them, with sometimes disastrous effects.
Luckily both Shining and Twilight appeared to be fine, other than some pounding headaches.
The Cakes had rushed over to them, apologizing profusely for their daughter’s actions, but the two were quite understanding. It wasn’t like the little filly meant to do it.
The two thanked the cakes for their wonderful service and took their leave, ready to see where else the day would take them.
The two siblings were making their way through the streets of town, continuing to chat as they went.
As they walked, they both began to notice the pounding in their heads subsiding, but a pleasant tingle seemed to be taking its place.
Neither sibling mentioned it, not wanting to ruin their fun day together.
Eventually they ended up on the edge of town at the Ponyville schoolhouse.
It was now late in the afternoon, and the school ponies had gone home for the day.
As Twilight looked over at the building, the playground caught her attention.
She remembered when she was younger and her and Shining would go to the playground together and play.
“Hey BBBFF, can you push me on the swings?” She asked him sheepishly.
She knew it was a silly thing to ask of him, but she really wanted him to for some reason.
Shining Armor looked over at his sister.
The question was a little odd, but he couldn’t say no to his best friend and sister.
“Of course Twily.” He said as Twilight began to run over to the swings in glee, her brother right behind her.
Twilight sat down while Shining took position behind her, using his hoof to push Twilight and get her started.
Before long, they had a good rhythm going, Twilight soaring higher and higher.
As she went, Twilight continued to focus on her memories of playing on the playground.
What had been a memory so long ago now seemed so recent in her mind.
That couldn’t be right though. Her and Shining hadn’t been to the playground since-
The tingling in Twilight’s brain seemed to be getting stronger, making it hard to think.
Little did she realize magic was messing with her brain, changing and rewriting her memories to fit the magic’s will.
All of a sudden, everything seemed clear.
Her and Shining had been to the playground just last week.
Time was hard for the little filly sometimes. She was just in kindergarten after all!
She smiled, becoming a lot more giddy and excited for a grown mare on a swing.
Shining was glad to see his sister having so much fun.
He remembered how much he loved playing on the playground when he was little.
His parents use to bring him all the time before Twilight was-
Shining too found his memory started to get hazy.
What were once memories of him playing on the playground by himself as a colt were replaced with memories of him and Twilight playing together.
Memories of the two being big brother and little sister were now as them being the same age.
Shining loved coming to the playground with his twin sister Twilight.
They loved always playing and learning together.
Shining began giggling and laughing with glee just like Twilight, acting like the kindergarten age colt he now believed himself to be.
Soon the two switched places and Twilight began to push her brother on the swing, pushing him higher and higher.
The two then went off and played with the other playground equipment, going on the teeter-totter, merry go round, and slide, all throughout laughing and screaming in childish delight.
Eventually, the two ended up in the sandbox, using their magic to try and make a sand castle together.
Their castle was coming along nicely, with Shining working on a moat while Twilight was working on the castle towers.
Suddenly Twilight began to feel a familiar feeling in her tummy.
She had to pee.
But she didn’t want to stop playing with her Brother.
She was having way too much fun to stop now!
She decided to hold it, wanting to wait until the castle was done.
This took longer than the young alicorn first anticipated however, and soon she found herself fidgeting as the pressure of her full bladder began to mount.
She looked around frantically to try and find a bathroom, but there was none in sight.
She was about to ask her brother Shiny for help when the inevitable happened and she began to wet herself.
Luckily, the magic affecting Twilight reacted in a flash, producing a large, foalish looking pull-up around the alicorn’s waist.
It was pink, with little designs running along the garment from front to back.
As Twilight began wetting her new pull-up, she was puzzled.
She didn’t remember putting a pull-up on this morning. She was a big filly! She hadn’t worn pull-ups in-
Twilight became distracted as her head began to feel funny, the tingly sensation returning with vigor.
It was making it hard to concentrate.
As it began to subside, Twilight came to her senses.
Of course she wore pull-ups! She was only two after all.
Her Mommy had gotten them for her when she started potty training.
Mommy said she was getting to be a big girl and it was time to start using the potty.
She hopped she wouldn’t be too upset she’d had an accident.
Meanwhile Shining Armor had finished digging the moat around the castle and looked over to see how his sister was doing, just as she began to soak her pull-up.
Had she been wearing one before? He couldn’t remember her wearing one since-
As Shining began to think about when Twilight had been potty trained, a pleasant tingle began to radiate through his mind.
He tried to focus, but found the pleasant feeling too hard to ignore.
At the same time, a pull-up poofed into existence around Shinin’s own waist.
It was just like Twilight’s, but in blue instead of pink.
As the tingling subsided, the new two year old colt came to his senses.
It had been that morning he’d seen Twilight in a pull-up.
Mommy had changed them into new ones when they got up.
He could see by the designs fading from the front and Twilight’s worried expression she had an accident.
He felt bad for his sister and wanted to help her feel better.
Looking down at his pull-up, he had an idea.
As Twilight pondered how upset her Mommy was going to about her accident, she heard a faint hissing sound.
Looking over, she saw her Brother Shiny blushing as the designs on his pull-up faded away.
“Me hwad awcidwent.” Said Shining as he blushed in embarrassment from what he did.
“Wit owkie. I dwid too.” Said Twilight as the two tots embraced in a loving hug.
The two then turned their attention back to their sandcastle, their soggy bottoms forgotten in their minds as they finished putting up the outer walls and adding some personal design touches before calling their creation complete.
“Awl hwail pwincess Twiley and hwer bwestest kwight Swiney!” She said, bowing as her brother clapped his hooves in approval.
“Wet’s gwo sow Mommy!” Said Shining.
“Yweah! Sow Mommy!” Said Twilight in gleeful agreement as the two got up and looked around the edges of the playground for their mother.
The two were surprised to find her nowhere to be found, and after a good bit of searching decided to head off toward town in search of her.
The two siblings started back toward Ponyville, their swollen pull-ups causing the two grown ponies to waddle like the overgrown toddlers they now were.
As the two wandered deeper and deeper into town, more and more ponies began to take notice of the siblings and their jovial appearance.
Many ponies stared oddly at the pair as they wandered about, looking in store windows to see if their Mommy was in any of them.
Some ponies tried to go up to them and ask if anything was wrong, but the only response they could get from either of them was if they’d seen their Mommy and if they could help them find her.
Some ponies were repulsed at the stale smell of pee that hung around the two, while some of the fillies and colts laughed at the spectacle of two adults wandering around town in soaked training pants.
Eventually Twilight and Shining ended up outside a toy store.
They didn’t see their Mommy when they looked inside, but all the bright and colorful toys looked so pretty! Surely Mommy wouldn’t mind if the two looked around a bit and continued looking for her later?
The two waddled in as fast as their legs could carry them and began to gawk in awe at all the toys that were spread far and wide.
The store prided itself on being a one stop shop, carrying toys and games for the youngest to the oldest of ponies.
A few customers turned to look at Twilight and Shining, smelling their stale pee soaked pull-ups as they walked by, the two occasionally giggling and fawning over a toy that caught their attention.
It wasn’t long before the two had made their way to the foal isle, where the simplest of toys and games were kept.
The two recognized many of these as being toys they were familiar with, only having stopped playing with them recently.
The isle contained other things for baby ponies too like cloths, formula, baby food, medicine, and much more.
Twilight looked over at a shelf where packages of baby diapers were kept.
Lots of sizes and colors were available, and one package in particular caught her eye.
On the front was a little baby filly, being changed by her Mommy into a new diaper.
Twilight remembered fondly being changed by her Mommy when she was in diapers. She liked the smell of the baby powder and her Mommy cooing down at her.
The magic effecting her activated, and her wet pull-up began to change.
The pink sides turned white and changed shape, separating and forming tabs with tapes on the end. They fastened to the garments front to fit snugly around her waist. The garment then began to expand rapidly, doubling, tripling, and then quadrupling in size, spreading the mare’s legs outward from the added bulk and making her bow legged.
Where a wet pull-up once was wrapped around Twilight’s waist was a clean, thick and white disposable diaper.
Twilight noticed the bulk and looked down, surprised to see her new diaper.
Where had her pull-up gone? She didn’t wear diapers! She was a big-
Before Twilight could finish her thought her head began to tingle once more and the little tot found her mind beginning to relax.
Her thoughts began to become simpler, easier, dumber.
Images of herself as a filly tot in her mind morphed and changed to that of a foal, only able to drool and play with the most basic of toys.
Images of herself filling her diapers also appeared, herself not concerned at all by her wet and messy diapers when there was fun to be had.
Back in reality, Twilight had stuck her hoof in her mouth and begun to suck on it mindlessly as a familiar full feeling in her tummy barely registered to the little foal’s mind.
Instinctively, she squatted down and began to push, her diaper beginning to expand in the back as the adult foal filled her diaper like the little foal she now was.
When she had finished, she plopped her bottom down with a squish, returning her focus to how nice her hoof felt to suck on, giggling and drooling as she did.
Shining meanwhile had been looking at the strange containers of foal formula when he smelled his sister’s accident and turned to face her, seeing his baby sister sitting contently in a foalish state of bliss.
Why was his sissy acting like a baby? They hadn’t been foals or worn diapers in-
Shining then felt a growing bulk between his legs and looked down, finding his own pull-up was now poofing up and changing to become a diaper as well, as thick and comfy as his sister’s.
He didn’t have much time to worry about it though as his mind too began to have thoughts more benefitting of a diaper wearer.
Thoughts of his Mommy holding him close and stroking his hair as she fed him his bottle, laying snuggly in his crib with his Brutus Force stuffie, and playing all day as he loaded his diapers filled his head.
His eyes became unfocused as he began to babble and coo, sticking his own hoof in his mouth.
The need to go soon overtook Shining as well as he deposited his own mess into his diaper seat and even began to soak the front, the baby colt enjoying how warm and squish his diaper was becoming and began to bounce in place, mashing his mess about and making audible squishes, much to his twin sister’s amusement as she too began to join in the fun.
Both the siblings spent the next hour like this until Twilight’s friends finally came and took them home.
They were concerned and shocked by what they found when they arrived, their friend and her brother acting like little foals in the toy store.
But with a little coaxing they managed to get them into a wagon and on their way back to Twilight’s castle, the two large foals falling asleep from tiring themselves out.
It had been a big day for them, and their friends hoped they would have everything solved by tomorrow.
By the next day things were in full swing.
Princess Cadance and Sunburst had arrived from the Crystal Empire to help find and conjure a spell to try and get Twilight and Shining back to normal, combing through Twilight’s library to try and figure it out.
Along with them were Pound Cake and Pumpkin Cake, who had changed a bit as well.
It hadn’t taken too long for the Cakes to relay what had happened to them and explain that Pound and Pumpkin had seemed to be getting more smarter and developed as the day had progressed.
Pumpkin had become quite book smart while Pound had become quite strong.
It was as if their personalities had been swapped with Twilight and Shining’s.
The two adult foals had quickly volunteered their help, especially since Pumpkin had pretty much started the problem to begin with.
Elsewhere in the castle, Twilight Velvet was with her daughter and son looking after them.
It had been Cadance’s idea to ask her to come, thinking that she would be best suited to look after her children while they looked for a counter spell.
The unicorn had been quite surprised when she got Cadance’s letter, and even more surprised when she saw her babies babbling happy at her when she arrived, but she was happy to help.
They were still her babies after all, and she’d always be their Mommy.
Velvet had quickly fallen into her old rhythm of keeping an eye on the two, playing and entertaining them throughout the day.
She looked after them with expert care, feeding them, changing their diapers, and rocking them to sleep.
A part of her was actually enjoying taking care of her babies again.
She didn’t see much of them with all their royal duties, and them needing her again left her feeling especially fulfilled and happy to be able to provide her babies everything they needed.
Right now she was making silly faces at Twilight who was in an oversized walker, giggling at her Mommy around her pacifier.
Velvet had dressed her little princess in a onesie and put a bow in her hair, finding them quite cute on her.
Shining was at her other side, currently trying to wrap his Mommy in a hug as he babbled and cooed at her in just his baby blue diaper.
Velvet couldn’t help but smile happily at her two babies. She wasn’t sure how long they’d be stuck this way, but she was going to enjoy every minute of having her babies back until then.
