Sister Says

by Scout Feather

Rating: mature
Tags: Original Character, Porn, My Little Pony: Friendship is Magic, Fetish, Sex
Length: 3391

A cute little filly is foalsat by her older sister, who has an entirely different view on what foalisitting should be.

A cute little filly is foalsat by her older sister, who has an entirely different view on what foalisitting should be.

This is a commission for Thunderchaser23

Contains: Foalcon, Diapers, Incest, and Diaper Rubs

Published 2019-09-30 01:20:01 UTC
Last updated 2019-09-30 01:20:01 UTC

Chapter 1

Glam Rock was supposed to be allowed to stay up late. That's what Mommy had told her, it being a weekend and all. There was no school in sight until the far-off future of Monday and such worries as homework and going to bed early were distant. Yet, her foalsitter disagreed.

Jazz Blossom was the worst kind of foalsitter. She wouldn't let Glam have any extra cookies, she was strict on the rules that had been set out prior, despite Glam's insistence that they were totally meant to be more of a guideline then 'rules'; and worst of all, she was Glam's sister. Everypony knows sisters make the worst foalsitters.

"But Jazzy! Mom said I could stay up late!" Glam Rock put on her poutiest face and widened her eyes to the size of saucers. A surefire hit for any grown-up to get her way, but to Jazz, it was simply and frustratingly ineffective.

"She did not," was the curt, slightly annoyed response. Jazz was doing her best to stay calm but the cracks were showing in her defences.

"Did so! She said 'Glammy can stay up late tonight if she wants to'," She stomped a little hoof on the carpeted floor of the living room matter-of-factly. In her mind, imagining herself a much bigger pony, the windows threatened to shatter and the entire room shook. In reality, the teddy bear nearest to her hoof wobbled and fell over.

"There's more to it than that and you know it!" was the snide response which came with a roll of her eyes. This had the desired effect on Glam, who faltered, chewed her lip, and plopped down on the ground. Jazz grinned with satisfaction; she'd won this round, but there would be more in the near future.

"She said I could stay up late...if I wore my special bedtime pants."

"Your what?" Jazz grinned devilishly. She knew, of course, but hearing her little sister admit defeat was oh so tantalizing.

"My special bedtime pants!" Glam outbursted, her cheeks aflame with a red hue.

"You mean your diapers, don't you?" Jazz trotted forth and bopped the little filly on the nose, "You mean if you wear you diapers like a good...little...foal!"

Glam turned a dark red, opening her mouth to protest. Instead of throwing a temper tantrum or yelling, she chose to take the high road. Hanging her head, the filly turned around and trotted off to her room.

Upstairs, Glam settled onto her bed, surrounded by fluffy pink bedspread and plushie animals galore. A fluffy pink diaper was spread out before her, unfolded and laid evenly across the bed. Glam shifted and moved herself onto it, until her bottom was touching the garment. With her hooves she pulled up the front, held it in place against her tummy, and brought the sides of the diaper up and around, taping it snugly in place. She shifted her bottom this way and that, feeling the bulk of it between her legs and restricting movement. Nice and snug, just as it should be.

Sitting up, the filly reached for her purple sleeper--a footed onesie covered in patterns from her favourite cartoon--and began sliding her hooves into the sleeves. One by one, she tucked herself into her jammies, feeling the extra bulk wrap around her rear, and pulled the zipper up her front. She had to bend over into a ball and grab the zipper carefully with her teeth, but she'd done this so many time she was practically an expert.

All dressed for bed and eager to stay up, Glam wiggled off of her bed and waddled to the staircase. As humiliating as it was to admit, her diapers were comfortable, even if they did bulk up enough between her legs to restrict movement.

"I'm all dressed and ready, can I come down now?" She called down to her sister, already setting hoof on the second step and descending.

"Fine. But you're still going to bed on time," was the response from annoyed sister. This earned a loud and dramatic groan of dissatisfaction from Glam.

Storming into the living room where her sister was watching T.V., Glam stood in front of the screen and glared daggers.

"Mommy. Said." She blurted.

"That I'm the boss and you have to listen to me. I'm telling you it's bedtime as usual." Jazz grinned, seeing her sister twitch and pout.

"Jaaaaaaaazzy! Why do you gotta be so meeeeean?" She dragged out her vowels into a high-pitched whine, starting to tear up a little in frustration.

Jazz started to relent finally, her armour worn thin. As much as she enjoyed the role of bossy older sister, she had a soft-spot for her little sister and still cared deeply for her. Seeing her get to the point of almost crying was not something she revelled in.

"Hmm," Jazz put a hoof to her chin, "I suppose we could stay up together. If you think you're grown-up enough to join me in my special game I was about to play. Otherwise, I'm afraid you'll have to go to bed!" She watched as Glam's expression soften, the little filly plopped onto her rear, nodding furiously.

"Of course! Of course I'm a grown-up! I'm a really big filly! I can do anything I want." Glam hoped that Jazz wouldn't draw attention to the diaper between her legs and how it so obviously served as proof to the contrary, but Jazz did nothing of the sort.

"Okay, Sis. Let's go to me room." Jazz reached over, shut off the TV and pried herself from the sofa, before trotting for the stairs rather quickly. Glam waddled behind her, struggling to keep up. Back up the stairs they went, little crinkles coming from a certain fillies rear each step they took. She tried desperately to minimize the sound but nothing helped, she just crinkled and waddled each step she went. Jazz snickered as she looked back, giving Glam a tousle of her mane when they'd made it to the top. Still, she didn't draw attention to the diaper.

Jazz's room always felt so much nicer to Glam. It had big-girl things like posters and neutral colours as opposed to Glam's bright pink room. She even had a little writing desk, and a much bigger, comfier bed. Glam scrambled up the side--it was much higher up than her own--and sprawled across it.

Jazz stretched out next to Glam. She hadn't said a word to the filly the entire trip, no teasing or mockery of her present state. As they lay next to each other, one of Jazz's forelegs reached out and crawled across Glam's tummy. She stroked in a small circle over the soft fabric, rubbing her belly.

"Hee!" Glam let out a small, barely audible giggle and shifted onto her back, letting her tummy face the ceiling as her sister gave her a nice massage, "S'nice, Jazzy."

"M-hm! Just wait until you see the super fun adult game. I learned at camp last year and it blew my mind." Jazz reached over and blew a raspberry on Glam's belly. The giggly filly let out a squeal and flailed her hooves.

"Eeeek! That tickles!"

The hoof on her belly started to wander in wider circles, making its way slowly down, further and further, digging through her jammies to massage at her skin underneath. Glam let her eyes drift close as she enjoyed herself. Jazz's sudden shift in mood was surprising, but wholly welcomed. She, too, was endeared to her sister.

Glam's eyes snapped open she unexpectedly felt her sister's hoof reaching for her diaper. Trailing around the front, filling the air with crinkly noises, applying firm pressure in different spots to press at her. She hadn't said anything yet, but still her head lifted just a little to watch what her sister was doing curiously.

The hoof made its way back and forth around her diaper, feeling where the waistband at the top, the leak protectors at each side and where they met her legs, and the bulkiest part of it at the moment. Her hoof pressed in and squeezed. Glam, still surprised by the turn of events, felt a weird tingle ripple through her body.

"J-Jazzy...isn't that my no-no place?" She asked quietly.

"M-hm. Don't worry Glam, this is the stuff I learned at camp. If you're really scared I guess we don't have to but you'll have to go to bed early, like I said. Only big ponies are allowed to stay up late and this is a game for big ponies."

"Nn...I guess it's okay, then." She laid her head back.

"Perfect!" Jazz's voice was louder than expected and caused Glam to jump a little, but it didn't surprise her as much as what she asked next.

"Can you wet your diaper? It's much better that way, trust me," Jazz hesitated sheepishly and blushed, "Uh, I would know."[

Glam was faced with a sudden dilemma and a surprising revelation. Was there really some way to make herself feel nice by making herself wet like that? She had to agree, when it was fresh and still warm, as it washed over her before the diaper soaked it up, the warmth was really, really nice. Good this be similar?

Glam bit her lip, eyeing Jazz, and must have showed some amount of concern on her face as she received a quick pat to the head, and the diaper.

"It's okay, Glam. It's easy and it'll feel wonderful. Do you trust me?"

"Yeah," Glam Rock admitted, shifting her gaze elsewhere. She tried to forget about her sister's presence. She pretended she was alone, in her room. When she'd tried slipping her hoof over her diaper a few times and felt tingly and wonderful. She realized this was the same thing.

Closing her eyes, she concentrated. A blush formed on her cheeks as she thought about pretty waterfalls, or the faucet in the bathtub running a nice bath. The thoughts of water had the desired effect and a familiar urge started to increase, at first just a whisper and then a crying need. Her bladder, full and ready to release, finally let go.

A faint hiss and sounds of crinkling filled the silence in the room as Glam started peeing herself. The pleasant warmth washed over her loins and bottom before the diaper soaked it up. It swelled, the padding taking every drop of filly pee from her.

Jazz had started rubbing her hoof over the filly's diaper again, stroking it to and fro. Her hoof squeezed, pressed, and patted the spots that had started to become thick and soggy.

"I-I don't think I can go anymore, sis." Glam shivered and let out a small squeak.

Jazz didn't respond. She'd reached over and grabbed the zipper of Glam's jammies in her teeth and tugged it all the way down past her middle, where it ended down near her groin. The sides of fleece jammies spilled open, revealing tufts of white fur that jutted out, and her white-and-pink patterned diaper. All the wetness indicators were flashing, though one barely needed it with how full it'd gotten.

The older filly stroked those adorable tufts of fur fondly for a moment, before her hoof made its familiar descent down to the diaper, stroking over the top and enjoying the warmth it radiated. It was too full now to really crinkle all that much.

"Wow, Glam, you really peed a lot. You know mom says it's unhealthy to hold it for too long."

"I know," Glam whispered, wiggling her hinds, rear legs splayed out due to the now-considerable bulk between them.

Jazz's hoof stroked up and down near the middle, right near the point where the diaper met Glam's fillyhood. The warm, soaked padding was pushed up against the filly's girl parts and pressed against her lips, splaying her vulva apart, touching her just inside. Glam squirmed and let out an unexpected moan.

"There's a good filly, Glam. See, like I said, it feels great!" Jazz was now sitting splayed out, her free hoof obscenely rubbing between her legs, pawing at her slit. She positioned herself so that Glam Rock could see what she was doing. The filly obliged, between squirming and shuddering gasps, she watched her sister touch herself.

"This is called 'masturbation', Glam. Does it feel nice."

"Really, really nice," muttered an out-of-breath filly.

Encouraged by her sister's approval, Jazz doubled down on really grinding her hoof into that diaper, pressing everything up against Glam's fillyhood, causing the diaper to squish. She grinded her hoof while her other hoof was busy between her legs, furiously rubbing her snatch. Jazz started to pant, and before she could speak, she heard a low, feeble moan of pleasure.

"Jaaaaazzy. Ooooh. That feels really nice now,"

Grinning, Jazz had no intention of doing so. She increased the pace of her grinding and went faster and faster. Under her diaper Glam was starting to hump back, her tiny nub showing itself and pushing out. She throbbed right as her sister rubbed and everything exploded. Her head got dizzy so she laid down flat, sticking her rump up, so eager for more. Her body language screamed for more so Jazz gave it, rubbing and rubbing and grinding her hoof.

"Jazz...Jazzy...Jaaaaaazzz! Oooh! Somethin's happening--Eeeeeek! Ahhh!" The filly screamed loudly as her body shook. Her hips lifted off of the bed and pushed back. Her eyes firmly shut, back arched, head up and screaming into the air.

"Jaaaaaaaaaaaazzz!" Glam moaned again as she squirted and came all over the inside of her diaper, further adding to the stickiness there. Her body went into overdrive as she humped into the air rapidly, even after Jazz had removed her hoof.

Jazz took her hoof back and applied both to herself, using one hoof to pull about her folds while the other pawed at her nub underneath. She gasped and bit her tongue as she came herself, arched her back and screaming breathlessly.

Both fillies collapsed next to each other in a satisfied glow. Glam latched onto her sister who eagerly pulled her close into a spooning position. Jazz cradled her, rubbing her mane and making her feel safe and warm.

"Geeze, Glam. That was sooo hot. I can't wait to do that again sometime." Jazz beamed wide as she nuzzled her sister's ear.

"It sure was fun, yeah. I didn't know I could feel like that. But...Jazzy?"

"Yeah, sis?"

"Could you, um...help me get changed now?"

"Do you one better, silly! Let's take a bath together!"

The porcelain tile was a cold and stark contrast to the warm and sticky diaper that Glam had just taken off, now sitting in a diaper pail. She waited impatiently for the water to be sufficiently warm while Jazz prepared the bath, even adding a little bit of bubbles.

Finally warm enough, Glam stepped up and peeked over the edge. She dipped a hoof in to test the temperate and smiled sleepily.

"Perfect! I love hot baths!"

"Me, too!" Jazz giggled as she stepped up behind her sister, grabbed onto her middle, and carefully hoisted her into the tub. She clambered in after her sinking into the water, enjoying how it felt on her fur and between her legs. She grabbed some soap and cleaned herself up quickly while Glam splashed.

When she was satisfied she'd washed the activities off of herself she reached out and tugged Glam closer. The filly struggled at first before relaxing, realizing Jazz's intentions.

"Gonna wash ya, silly filly. Hold still," Jazz explained, reaching for the shampoo and lathering it into her mane. Glam cooed and melted under her hooves.

For a little while, the two sisters sat in peaceful silence while Jazz washed her younger sibling, soaping up her hooves, tail and even giving her tummy a rub. Her petite rear was last and required extra care to wash away the lingering pee and scent. Jazz carefully cleaned all around her thighs, bottom, and just above Glam's naughty place.

The filly was standing on all fours, her tail draped over her back so as to be out of the way, her little hooves spread apart. Jazz fought back a blush as that tiny, puffy, slightly-red filly pussy stared her in the face. She cupped it with her hoof, puled at one of the lips, rubbed it sensually. Arching her back, Glam moaned.

"I got one more game, Glam. Ready for round two?"

"Already! Yes please!"

And without warning Jazz leaned forward, dragging her tongue from the bottom of her fillyhood all the way to the top, letting her tongue start to press between her tight lips, prodding forward. She lapped again and again, her hot breath bathing over her tush. Glam clenched up almost immediately and moaned readily.

"Oh gosh! I pee from there, Jazzy! Ahhh, are you sure about this?"

"Oh, very sure," Jazz licked her again, starting to prod her tongue between her folds until she wormed her tongue and inch or so into those agonizingly tight filly folds. Testing her limits a few times by pulled back and forth, and earning a shudder from Glam, Jazz knew it was time. She started wriggling her tongue back and forth, jutting it forward and deeper into her. She thrust it back and forth, suckling and nibbling at one of Glam's labia.

Glam rocked back and forth as she shuddered and struggled to contain her moans. She knew what to expect in the end but the journey there was so new and exciting that she could barely contain herself. She lifted a hoof, for leverage, and to Jazz's suprise, started to drip from inside.

"Ohh...It's happening again, sis. Almost."

Jazz found her clit, latched on and suckled.

With a loud squeal Glam mashed her face on her sister's muzzle and came with a shuddering squeak.

The filly had slipped and nearly fallen into the water had her sister not caught her. Pulling the filly back up to her hooves, Jazz cleaned off her residual filly cum, wiped her own muzzle off, and carried the filly off in a fluffy towel.

"That's called cumming, Glammy," Jazz whispered as she patted her down with the towel, "And you're really, really hot when you do it."

Glam for her part could barely stay awake and thus simply accepted what was being told to her with a sleepy nod of her head. When she was sufficiently dry and so was Jazz, the bigger sister picked up and carried the filly to her own pink room.

Glam did not protest, nor object when her sister helped to redress her, slipping a fresh, fluffy diaper under her bottom, taping it around the front snugly, and wiggling her back into her jammies. She started to squirm, though, when Jazz began to tuck her in.

"Noooo," she whimpered, "With you!"

Jazz didn't have it in her to object, so picking Glam up, she trotted back to her own room and deposited the filly on her bed. She crawled in on the other side and tucked the covers around the smaller sister, pulled her up into a hug same as earlier, and kissed her on the cheek.

"G'night, sweet Glam," Jazz whispered, smiling at her cute sister, who smiled back in her sleep.

The little filly stirred and turned in her sleep, seeking out the warmth of her sister's body. Jazz gladly accepted having her snuggle into her chest and draped her hoof around Glam. The filly snored, and though Jazz knew she wasn't about to sleep much, she wouldn't have it any other way.

The next morning, as sunlight cracked through the window, Glam awoke to tufts of her in her face, a familiar and unpleasant sogginess that felt cold and clammy between her legs, and a pleasant contentedness over her body that she couldn't quite place. She squeezed her sister, yawned, and rubbed her eyes, thinking about the fun night they'd had together, the new activities she'd learned...

...and how she'd fallen asleep early, ruining her one-time chance at staying up late. Frowning, she curled her muzzle and blurted out.

"Buck!"

Jazz awoke with a start, peered around the room and let her eyes fall on Glam. She took a moment to process what had been said before blinking in surprise.

"Glam! Language!"