Reposted from my deviantArt account.
 
“The Sweetest Little Model”
 
“Sweetie Belle was hanging out at Sweet Apple Acres with her friends Applebloom and Scootaloo, sampling the Apple family’s newest cider, made with their rare Zap Apples.
 
Suddenly, Sweetie remembered that she had volunteered to help Rarity with a very important project she was working on. After finishing off her ninth cup of Zap Apple Cider, she said goodbye to her friends and rushed off to meet her sister at Carousel Boutique.
 
When Sweetie arrived, her big sister quickly took the little unicorn to her work room, where she began her project. At first, Sweetie simply sat and watched her sister work. She had always admired Rarity’s skill with her sewing materials, but so far, she couldn’t tell what exactly her sister was making. So far, it was looking like a shirt, but if that’s what it was, it looked like Rarity had just about finished with the project, making Sweetie wonder why Rarity needed her help in the first place.
 
Then Rarity set down her project and her sewing supplies, instructed Sweetie to lie on the floor on her back, and then left the room. Lying on her back, Sweetie began to feel a slight pressure building up inside her. That Zap Apple cider was starting to catch up with her, and she’d need to pay a visit to the little filly’s room very soon.
 
Just then, Rarity returned to the room, carrying a large bag. She set the bag down next to Sweetie, and pulled out a diaper. Rarity then explained to Sweetie that she was making a onesie for her client, and she needed Sweetie to wear the onesie while Rarity worked on it because she didn’t have any mannequins small enough for the onesie to fit, and she needed to wear the diaper so that she could properly make the onesie fir around a diapered rump.
 
She lifted Sweetie’s rump off the floor and slid the diaper underneath. She wrapped the diaper around her little sister’s waist, and stood her back up. Sweetie blushed as she looked back at her now padded rump. Rarity then slipped the unfinished onesie onto her now padded little sister, and resumed working on the rest of it. Slowly, the pressure inside Sweetie began to grow more and more intense, and it was getting increasingly difficult to hold the floodgates closed. She tried to explain to Rarity that she needed to use the bathroom, but Rarity was so wrapped up in her work, she told Sweetie she couldn’t allow for even the slightest delay. After a brief pause, Rarity reluctantly suggested that Sweetie just use the diaper she’s wearing, much to Sweetie’s embarrassment. As much as she just wanted to relieve herself, Sweetie chose to try and hold it.
 
Finally, after what felt like hours to Sweetie, Rarity finally finished the onesie. She took a moment to admire her work, as Sweetie stood there with her hind legs crossed. Out of curiosity, Sweetie asked Rarity who the client was, seeing as the onesie was far too big for an ordinary foal to be wearing.
 
Rarity lovingly picked her little sister up and held her close, unknowingly putting a slight pressure on Sweetie’s stomach.
 
“My client is the only little foal big enough to wear this adorable little outfit,” Rarity whispered sweetly to her sister, “ and that little foal is my little foal.”
 
With that, she squeezed her little sister in a tight hug, as Sweetie felt a sudden warm wetness fill her diaper as she realized that not only was the onesie made for her, but that she suddenly didn’t have to go to the bathroom anymore…”