Rarity whined as her mom nudged her along towards the living room of their family home, her younger sister hopping about, looking eager for playtime. "But mom, I want to work on my dress," The fashion filly was no older than ten while Sweetie was around four.
Cookie Crumbles shook her head. "Now come on, your sister wants to play. Don't you want to spend time with your sister?"
"Ya sissy play!" Sweetie chimed, skipping about as Rarity begrudgingly walked into the room yet was smiling all the while. It was just something about Sweetie's energy that was infectious.
"Okay, we can play," Rarity said, setting her small red glasses somewhere safe before turning to her sister. "What do you want to play?"
Sweetie sat down, tapping her chin as she thought about it. "Well, we could draw, oh oh or make a puzzle, or dance!" She clapped her hooves before staring at the dollhouse in one corner and the baby pony doll. "I know we playhouse!"
"House?" Rarity asked, seeing what her sister was staring at. Moving over to the dollhouse, she sat down waiting, although Sweetie giggled.
"Yeah, House, I play mommy, and you be da foal," Sweetie Belle said with a slight voice squeak.
Still thinking Sweetie meant the dolls, Rarity picks up the small foal doll. "Why can't I play the mommy?"
"No, I wanna be mommy," The filly stomped her hoof before glancing at the doll and back at her sister. "Hehe, foal needs to dress up!" With that, she scampered across the room to a small trunk pulling open the lid with a grin.
Rarity blinked, staring at the doll in her hooves. "This doll looks fine to me, Sweetie Belle."
"No, sissy needs to dress up," Sweetie replied as she dug around soon, showing off items.
Rarity instantly started to blush upon seeing them. An oversized foal diaper was perfect for her size, along with a pink bubble sleeve dress and matching bonnet. "W-what? B-but it is just a game; I do not need to dress up." The thought of why they had such items was not even crossing her mind.
"You foal, you need to look the part," the filly insisted as she brought the items over.
"B-but that is so embarrassing!"
Sweetie pouted before taking a breath. "Mooom, Rarity will not play with me!"
Cookie replied from the kitchen a second later, apparently now making a meal. "Rarity, play nice or no trip to the sewing store."
"Ugh!" Rarity moans, putting her hooves to her beat red face. "Fine, I will dress up." Upon Sweetie cheering, Rarity hesitantly laid down, having to help lead her younger sister on how to apply that thick garment to her flanks. It only added to her embarrassment of telling her each step, having to assist in some spots as her tail was tucked through, and watching her sister pull it up into place. Once they would work together to make sure the diaper was secured snuggly, Rarity cannot help noticing how soft the garment was and rather loud she had to note too.
"Now the dress," Sweetie sang as Rarity wobbled as she sat up, having to lean over so her sister could slide the dress over her head and the forelegs in the sleeves. "Aww, pretty."
Rarity muzzle could not possibly be any more flushed as she shifted around, looking at a mirror that was in the living room as well. Something about the dress seemed familiar, like she had seen it in her foal pictures in the family album. "Is that all?"
As if to answer, her sister rushed back to the trunk, giggling as she digs a bit more before returning to Rarity with more items. "Nu-uh, mommy's foal needs more." She held up the large white bib with a duck on it, securing it around Rarity's neck before happily sliding purple booties on each hoof secured by velcro. "Yay, the foal will help mommy dress up too?"
"A-alright, Sweetie, I will help," Rarity said as she got up only to slip and fall back on her rump with a poof of air, a scent of foal powder in the air despite not having been applied. She groaned as her younger sister laughed a bit as she got back over hooves carefully and felt sheepish as she had no choice but to waddle her way to the trunk. Shifting through the blankets and other outfits within, the elder sister soon found what she figured would work as she lifted out a dark purple dress with a large white apron with pockets. "I think this should work."
"Yay!" Sweetie cheered happily, lifting her hooves as her sister helped dress her up, even adding a pink sun hat with flowers embroidered into the fabric placed on her head. Once done, the little sister smiled, reaching up and booping her sister's nose. "Good foal."
"So, what are you going to do first?" Rarity asked, watching as her sister digs out a comb and some ribbons.
"Brushies then feeding," Sweetie replied, beaming as Rarity sits down once more next to the couch as her sister climbed up on it so she could reach before starting to groom the mane. "Foal's mane smells nice," she muttered as the filly kept brushing. A few minutes passed before Rarity felt a light tug as Sweetie managed to tie a large bow into the mane. "Hehe, okay, now mommy is going to feed you." Hopping down, she grabbed Rarity hoof, walking her along towards the kitchen.
When they reach the kitchen, Cookie Crumbles immediately awwed and was trying to hold back a snicker. "Oh are you playing house, little one," she asked Sweetie Belle."
"Uh-huh, now mommy gotta feed her foal," Sweetie said as she patted Rarity's big diaper.
Rarity wondered what Sweetie Belle was going to feed her? Hopefully, Sweetie Belle was not cooking! She burnt juice before!
"Oh, don't you pout. I have gotten a lot better at cooking." Sweetie Belle explained that an easy bake oven was in one corner. Rarity watched as the filly hurried over the toy and began muttering and doing random things and somehow came back to the table with a large bowl of applesauce. Her mom fetched her over the colorful spoons as well.
"Oh, do not forget the baby needs her milk too!" Cookie Crumble exclaimed as she placed a foal bottle on Rarity's table tray
"T... that is not breastmilk, is it". Rarity whined, poking at the bottle. It even felt warm to the touch.
Cookie Crumble winked, "of course, only fresh mama milk for the baby."
"Moooom!' Rarity whined and watched as Sweetie spooned up some of the applesauce to her lips.
"Hehe, come on, open up, choo choo," Sweetie sang, giggling every once in a while.
Rarity shook her head, placing her hooves over her mouth, and snapped, "I wana feed myself."
"No, I'm the mommy, and mommies feed their foals," Sweetie said matter a factly as she pokes the spoon on Rarity's cheeks to get them dirty. "Uh oh, you messy eater, hehe. You da foal remember?"
"Mmmm, b-but," Rarity started but felt her sister pop the spoon in her mouth when she tried to retort. Their mom giggled at the adorable sight.
"Oh come on, Rarity, let Sweetie have her fun," Cookie mothered, wagging her hoof.
Rarity chomped down on the food eventually, but with a pout, this was beyond humiliating...but the applesauce at least was not bad. She let her sister continue feeding her, the bottle almost taunting her with what would come next as it went on. Bit of the sauce ended up on her cheeks and her duck-themed bib regardless. Sweetie lifts a cloth dabbing at her sister's cheeks.
"Baba time," Sweetie said before quickly popping the nipple into her sister's mouth.
Rarity was hesitant to drink it at first but looking into Sweetie's puppy dog eyes made her give in as she began to slowly suckle and swallow down the milk, feeling fuller the move she drank.
Something felt off after the bottle popped out of her mouth; she felt bloated, and her mind was hazy… "oh, my head hurts…." Rarity mumbled, rubbing a hoof over her head, feeling almost tempted to suckle on it.
"Oh dear, I think the baby needs a checkup." Cookie Crumbles chimed. "Better pat her back, Sweetie Belle. The foal has gas."
"Okay," Sweetie did as she was told, happily patting her sister's back, waiting for the burp to happen.
Rarity whined a bit as the pressure in her tummy grew before she felt a sizable unladylike belch leave her mouth, letting out a sigh when she felt better. She eeped suddenly when Sweetie poked at the diaper too. "H-hey! I most certainly will not be using this thing."
Sweetie gave her sister a hug nuzzling her. "Mommy loves her foal." She then nudged Rarity to move back to the living room. "I wanna read to the foal."
Getting up, the older sister waddled next to her sister till they returned to the living room Rarity seeing a bookshelf full of picture books and asked, "Can I pick one out, mama?"
Sweetie Belle dawwed, "aww, you called me mama."
Rarity squealed, feeling a bit embarrassed. "Just part of the game," she said, slimming the various colorful covers with cartoon critters on them. However, the names of them would seem to change whenever she would blink.
She then squeaked as she felt a hoof pat her bottom and turned to see Sweetie Belle with her cheeks flushed pink. "Sorry, just checking."
"N...not gonna use my diaper! Do not have to check it every few minutes." Rarity snapped before picking out a book with a white cat on it. It reminded her of Opel.
"Oh, this is going to be a good one," Sweetie Belle chimed as she led her sister to a soft armchair. She then tapped the seat Rarity sat down, letting her sister sit between her forelegs. Sweetie smiled as she opened up the cover, slowly reading out the words. Rarity rubbed her eyes some as the words never seem to be the same for very long. "Once upon a time." As the story went on, Rarity started to feel sleepy, slumping a bit as she listened to Sweetie's voice read, the filly stumbling on a few words here or there. After another minute, the big foal dozed off, closing her eyes fully.
When Rarity woke up, she was now strapped in a stroller hugging a plush bunny, and straps went around her. She felt something rubbery in her mouth...and she suckled on it, realizing it was a pacifier in her mouth. "Mmmm?" She looked around, confused cheeks starting to turn crimson again. The suckling was somewhat soothing, however, which just encouraged her to keep going.
She looked around, seeing she was at some park with trees, fields all over. She scrunched the diaper around her rump, and her cheeks flushed pink as she found she would wet herself. "Mmm!"
"Oh, do not worry. I know you are wet, but it's only a little; we'll be wasting a diaper if I change you right now." Sweetie said as she came into view. She was now somehow much older, while Rarity was much smaller.
"Mm mmhm," Rarity whined, holding the plush up her muzzle as if to hide from view. Somepony might see her like this; how dreadful. Her suckling only increased, helping her to stay calm the more she did it.
Other ponies were walking around the park and saw that they weren't shocked and treated her like a foal dawwing and waving their hooves at her. Sweetie reached down and began to tickle Rarity's tummy. "Coochy coo, who a happy filly, yes you are!"
"Nuuuu hahaha!" Rarity squealed, kicking her hooves about as she tickled, pushing her hooves against her sister's in an attempt to stop it
"Oh, what a cute little foal," a strange mare commented as she came over Rarity. The mare in question had a dark purple coat and a very strange mane being an ethereal blue with shimmering stars in the mane. Her eyes were a dark violet as well and were quite calming. It felt rather soothing to stare at her.
"Hehe, this is Rarity, my little sister," Sweetie said, patting Rarity's head.
Rarity blushed, looking into the mare's eyes, slowly lifting up her hoof and waving. "Hewwo," she lisped.
"Oh, such a cutie trying to talk, can you say mama?" the mare asked.
Rarity sheepishly partly hid behind her plush. "Mmm, a mama."
"Oh good filly," the mare coo lifting the foal out of the stroller and kissing the forehead, soon placing Rarity into a foal swing. "Time to fly."
The white-coated filly squealed, throwing her hooves in the air, having so much fun as she got higher and higher with each push... Her laughter was heard all over as she chanted, "fly fly fly hehe," She felt like a pegasus as she was pushed.
Sweetie Belle, after a few minutes, gave Rarity's diaper another check, "oh, I think it's time for a change."
Rarity kicked and whined, "no diaper change! Keep playing!"
Sweetie Belle snickered, "now, now don't want a rash, do you?"
"Mmm, guess not," Rarity grumbled, not even being mad about using her diaper.
The purple mare watched from the side as the foal was changed; Rarity wiggled around during the process. Sweetie cooed. "Aww, aren't you excited little sis?"
Rarity couldn't help but kick and giggle; she had so much energy! Sweetie Belle struggled a bit but was able to tape a fresh diaper over her little sister's bottom. "Hehe, that tickles!"
"Oh, maybe she would like the sandbox," the ethereal maned mare suggested pointing over to it where a little Fluttershy was playing.
Rarity got excited, bouncing up and down on her diaper. "Wana play with Fluttershy!"
"Okay, come on, but you have to stay in the sandbox, okay?" Sweetie Belle replied as she placed her sister down in the sandbox.
Rarity shouted, "Yes, mama!" She then toddled over to Fluttershy, who looked up, "Hey Rarity, wana help me make a sandcastle?"
"Yeah! I'm gonna help!" Rarity exclaimed as she clapped her hooves and started to dig through the sand, looking for diamonds. She found all kinds of jewels helping to make the sandcastle look "pretty" while Fluttershy built the towers and placed a plush bunny in the middle of the castle.
"Tis is king bunny!" Fluttershy explained.
Rarity tapped a hoof," taking needs a crown." She then dug around the sandbox and gasped, seeing a little plastic crown. "Look what I found!"
"Oh! That looks cool!" Fluttershy cooed as she placid on her plush.
The purple mare soon leaned down and nuzzled the two. "Hehe, see, aren't you having fun?" She asked Rarity directly.
"Uh-huh," Rarity nodded, shifting about and crinkling.
"That is good, just remember to have fun all the time," she said before walking away.
Rarity scratched her mane, wondering who that strange mare was; she shrugged and went back to playing without a care in the world. A lot of time must have passed when Sweetie Belle picked her up, and her diaper was changed again (this time, it was much more used than before)
Rarity realized she must have shrunk even more, and Sweetie Belle hasn't changed much, looking down with a smile at her. Although she found her mouth lacking teeth, the filly wanted to speak, only having two small one's upfront. She wanted teeth on something too. Sweetie cooed at her, slowly cradling her in her huge hooves. Rarity was then placed into a foal carriage being laid down and wrapped up in some blankets, hugging her from all sides and holding her head in its wrap. A pacifier was then popped into her mouth, which she happily began to suckle away on.
"Alright, just get some sleep," Sweetie whispered as she pushed her sister through the park. Rarity started to close her eyes as she did instead feel tired after a gentle hisss, and she felt her bottom feeling warm. However, it didn't matter to her because she was feeling so relaxed being a newborn foal…
Rarity yawned as she awoke the following day. Slipping off her mask, she looked at herself, overseeing that she was a grown adult. She lifted the blankets to ensure she wasn't wearing a diaper and saw nothing of the sort.
"Oh, that is a relief," Rarity sighed and shrugged, "it was just a strange dream."
Climbing out of bed, she stretched out her limbs. She was thinking about the dream despite it being not very comfortable. It was a pleasant and relaxing dream. "Mmm, I shall have to give mam-no..my sister a big hug the next time I see her."
The white-coated mare's face turned red, hoping nopony heard that, "maybe I should have Twilight send a letter to Luna for me." She walked off, going downstairs to make breakfast for herself and her sister, secretly having a craving for applesauce.