Princess Twilight Sparkle's Undertaking

by Certificate

Rating: mature
Tags: Adventure, Princess Celestia, Sex, Twilight Sparkle, My Little Pony: Friendship is Magic, Princess Luna, Thriller, Porn, Fetish
Length: 3273

Alicorn Twilight Sparkle is tasked by Princess Celestia to hold in her pee for an entire week. Unbeknownst to her, this will end up being only the beginning of her full bladder-centered adventure.

Twilight Sparkle-- a nerd, book pony, and now a Princess of Equestria-- is tasked by Princess Celestia to hold in her pee for an entire week. Fortunately for her, holding in her pee and keeping her bladder full is something she's familiar with, but the stretch of seven whole days is something she'd barely even gotten halfway to in her previous and personal ventures. Unlike other mares, however, her external urinary sphincter isn't the only form of control she has over her bladder... and with a helpful gift from Celestia herself, she may just be able to reach an entire week.

...And then realize that was only the beginning of her adventure.

Original cover art belongs to Bugplayer
This is a fetish-centered story that's focused on full bladders and pee desperation.

Published 2018-04-20 19:40:06 UTC
Last updated 2018-04-20 19:40:06 UTC

An Early Close Call

"Mmmph!!!"

Twilight Sparkle paused going up the long, spiral staircase that lead to her bedchambers to rapidly tap her hind-legs against the steps, squeezing her eyes closed and arching her neck upwards. She had to pee so badly! The next morning her bladder would've had four whole days worth of pee inside of it-- that was four whole days... and it was all begging to come out. She opened her eyes back up and took a deep breath, looking up at the stairs in-front of her. Her body was trembling and her breathing was shaky; She was so close to relief, but her external urethral sphincter was so tired after consciously holding in her pee all throughout the day. She was absolutely exhausted, but she had to push through for just a little longer. Taking a deep breath and holding the air in her lungs, Twilight puffed out her cheeks and frantically charged up the spiraling stairs in a mad dash. Alarms were going off in her mind telling her just how close she was to letting out her pee, leaving her in a constant state of panic as she struggled with her quivering hold. Her desperation to urinate was driving her crazy, and having to go up tons of stairs just to get to her bedroom in one of the Canterlot Castle's Towers wasn't making it any easier. She didn't stop charging up the steps-- the faster she ran, the faster she wouldn't have to deal with them anymore, and the faster she'd be able to give her poor, tired urinary sphincter a rest. At least, that's what she thought...

She was only about ten steps away from her door when she was unfortunately forced to stop again; her desperation had reached a peak, and she felt like she couldn't hold anymore. Her whole body tensed as still and solid as a statue, with all four of her hooves locked straight as she focused every bit of her strength on squeezing her exhausted urethral sphincter. Her bladder had been bothering her for so many hours all throughout the day, and it was letting Twilight know that it wanted to be emptied... right now.

"Nnmph!!!!!!!"

Twilight arched her neck upwards again as her exhausted holding muscles began reaching their limit. She knew this feeling all too well-- her desperation had reached a critical point to where it felt like she couldn't physically squeeze hard enough to push her pee back inside her bladder where it belonged. She sharply breathed in past her tightly clenched teeth, before tapping all four of her hooves against the steps so fast they looked like a blur, doing anything she could not to let her pee get to that point. She could barely stay in control of her own bladder! Her backside started to lower down towards the ground, and her hind-legs pressed and rubbed against each other as she continued to violently tap them against the steps in a vain attempt to do anything possible to help her squeeze just a little harder. She continued until she accidentally misplaced one of her hind-legs, and in an instant the purple mare's eyes went wide with fear as she abruptly lost her balance and began tipping backwards down the steps.

"AHHHH!!!!" Letting out a gasp and a high-pitched yelp, Twilight squeezed her eyes closed and curled up in a ball as she tumbled down the stairs. She could feel her stuffed bladder's contents tossing and turning from within the big bulge located at her lower-abdomen, sloshing around and driving her bladder crazy with pain and pressure as she toppled against the steps. Eventually she managed to stop herself from tumbling down any further, stopping her momentum by pressing her hind-hooves against the wall and the center column of the staircase. She had fortunately managed to stop herself while she was right-side up, with her flank pressing down against the steps. Her hind-legs were spread wide apart and tense in this position, with her left leg pressing against the center column and her right leg against the wall to her right.

Twilight panted and trembled slightly, staring ahead of her for a few seconds as she tried to recompose herself. It didn't take long for her gaze to trail downwards, where she found herself staring at the huge bulge that was so blatantly visible at her lower-belly-- with her hind-legs spread apart, everything down there was easily visible. The large bulge belonged to nothing other than her bladder, which had been unable to empty for over three and a half days now-- all thanks to Twilight herself. She admired it for a short time, before her gaze trailed down even lower, down towards the reason that her bladder was still so full and not currently emptying all over the stairs.

Down in-between her widely spread hind-legs was her big and plump marehood, which was always very easily noticeable due to just how large and puffy the outer-lips were-- they were huge! They were currently pressing against each other, which was something Twilight had done right before she fell. The instant she had felt herself begin tipping over, she knew that there was no way she would've been able to keep holding it using her exhausted, quivering urinary sphincter, so she let go of it, relaxing it, and held it by pressing her lower-lips against each other instead-- something special that Twilight had learned she was able to do. She continued to pant, slowly catching her breath as she found herself staring at her blatantly exposed marehood. The outer-lips were visibly pressing hard together, keeping her urine from pouring out like her bladder so desperately wanted. If it wasn't for them and her talent of being able to press them together, she definitely would've lost control when she fell-- her pee would've been spraying and splattering everywhere as she tumbled down the stairs.

"Wow that was close.. I really need to be more careful." Twilight muttered softly to herself. She had wanted to save her ability to use her second pair of 'holding muscles' while she was doing her nightly bathroom chores so that they would go by alot easier, but that ultimately ended up costing her. It had taken alot of effort to hold it through all of that tumbling, and her big and plump outer-lips were already starting to feel tired... She continued to stare at her marehood for a few more seconds, and she gulped, before slowly and carefully getting back up. She had finally caught her breath by now, and upon getting back on all four of her hooves, she quickly began to make her way up the stairs again.

With careful steps, she eventually made it up to the top, and she opened the door, walking into her large bedroom. Twilight Sparkle's bedroom consisted of well-decorated walls, floors and ceilings. The room was colored with different shades of pink and purple, with a large, lavish carpet that fit in perfectly right in-front of her bed. Twilight's bed was a huge, inviting bed that was so big that she wouldn't be able to stretch across both sides of it, even if she was twice as big as she was. It consisted of pretty pink covers, a large assortment of pillows lined and positioned neatly at the back, and light-pink, slightly see-through curtains that lined the entire perimeter of the bed. In-front of the bed and against the wall was a long wooden dresser, with all sorts of different objects positioned neatly on-top of it. A huge and clear mirror was attached to the wall right above the dresser, and to the right of it all were glass doors that lead to a small, circular balcony.

Twilight glanced at her huge bed, feeling tempted to just call it a day, but she still had things to do first. Stepping to the right of the bed, she walked past it, keeping her hind-legs close together as she made her way into her completely open walk-in bathroom. Her hooves changed from walking on deep, purple carpet to small white and light-blue tiles, and it didn't take long before she found herself staring at the toilet. It was sitting there with the lid open, almost begging for Twilight to just plop her flank down on-top of it and let all of her bladder's stuffed contents out. She really wouldn't mind doing that right now, to just let go and empty her poor bladder after so long... but she would never let Celestia down like that. It would've been okay if she was holding it in for her own personal reasons, but this was something different.

Furrowing her eyebrows, she made her way over the bathroom counter, fidgeting slightly as she did so. All she had to do was brush her teeth for the evening, and then she'd be free to go to bed and give her exhausted external urinary sphincter a well-deserved rest all night long... Letting her hind-legs press together as she stood mostly still, she levitated her toothbrush out, looking down at the bristles as she squeezed out a small bit of toothpaste onto them. She proceeded to look up at the mirror in-front of her, staring at herself for a few seconds before beginning to brush.

Her desperation became more obvious the longer she spent brushing. Her squirming and fidgeting gradually became more prominent; her hind-legs tapped against the tile floor with increasing speed and intensity, and she groaned a little as she brushed faster. She was still making sure that she was keeping her plump outer-lips securely pressing together, but they were already getting so tired. She wasn't able to keep them pressed together for very long-- maybe ten minutes at most-- but this time it was different. Her bladder was so incredibly restless, constantly contracting and trying to push out its contents, and tumbling down the stairs hadn't of helped either. Her bladder wanted to empty.

'Why did I have to fall down the stairs?' Twilight thought to herself with another groan. She squirmed her backside back and forth a little over-dramatically, struggling against her hold, and before long, she had finally finished with the brushing.

With her flank cheeks pressing hard together, Twilight rapidly tapped her hind-legs on the tiles below as she took the brush out of her mouth. She turned on the faucet but then cringed when she heard and saw the water begin splattering out into the sink, making her tap her hind-legs even faster as she began to rinse off her toothbrush. At this point she was starting to look like a little filly doing a desperate pee-pee dance-- she really needed to go! She wasn't able to keep still, constantly walking in place and squirming in her attempts to hold back the flood and keep those puffy lips of hers pressed firmly together. Twilight quickly filled her mouth up with water, swishing it around speedily and rinsing out her mouth before spitting it all out a few seconds later. She spit one more time, before hastily trotting out of the bathroom-- that was all she was doing! She would finally be able to get on her bed and put and end to her increasing distress...

Twilight panted lightly and fidgeted as she approached her massive bed, walking in place faster as she prepared herself to jump, before hopping up onto it shortly afterwards. She nearly ran all the way over to the center before abruptly laying down on her back, slamming her hind-legs together as soon as she did. She looked down at them, feeling and seeing them tremble softly as she jerked her body back and forth in her desperation. She gazed at them for a little while longer, before looking down further towards something special-- her marehood. She could visibly see the plump and puffy outer-lips shaking in their exhaustion, and she gulped. Her hold on them was getting so much less responsive... She felt like she was missing something, however-- something vitally important. Something that was supposed to make this all so much easier... She began readying herself to close the light pink see-through curtains of her huge bed, before it suddenly occurred to her what she was forgetting, and she gasped.

"The crown!"

Twilight surprised herself at how she had forgotten something so important to keeping her bladder full-- how would she have been able to get to sleep and hold it in throughout the whole night anyway as she was? She could barely keep holding it! Her horn began to glow, and a small, well-decorated box that was laying on-top of her dresser began to glow. She levitated it over to her and then changed the direction of her magic output as she quickly closed all the curtains, squeezing her eyes closed and then pressing her hind-legs even harder against each other. Her control over her lower-lips was quickly faltering, and she knew she had to hurry before they got too unresponsive...

She unconsciously began to hold her breath, and her hind-legs trembled as she struggled to keep her plump outer-lips pressed against each other. She looked down at the box and quickly opened it, revealing something special that Celestia herself had personally gave to her-- a small crown. It was much too small to fit on her head, but it was the perfect size for something else... Something that was personal and precious. Something that was currently in-between her hind-legs and trembling desperately.....

Twilight shakily exhaled the breath that she had unknowingly been holding as she levitated the small crown out of the box, sitting up on the bed and scrunching her face up in her desperate attempts to press her hind-legs even harder together. She quickly levitated the crown over to her marehood, feeling her hind-legs shaking even more as she struggled to be as still as possible, before carefully positioning it on-top of her plump, quivering outer-lips. She watched them as they trembled, increasingly straining to stay pressed together despite their exhaustion... Her entire body was tense by now, and she began to hold her breath again as she tried to make sure the crown was placed perfectly on-top of her puffy outer-lips. She only had to last just a tiny bit longer..!

Twilight's heart was pounding fiercely in her chest, and her eyes narrowed as her face scrunched up even more. Her big outer-lips began to quiver more and more, and Twilight saw it. They were getting so exhausted.... She was already lucky that pee hadn't begun slipping out from between them! She would hate to get any pee on her warm, lush covers, but the crown needed to be on just right... Unable to take anymore though, Twilight gasped and pressed on a small red jewel that was on the crown, causing it to begin gently but firmly hugging her puffy outer-lips together. As soon as she felt like it was on correctly, she immediately relaxed, letting her exhausted outer-lips make one final, weak quiver before completely relaxing... After seeing not a single drop of pee drip out, Twilight breathed out and let the back of her head rest against the bed as she relaxed every muscle in her body. She began to smile, and she started to spread her hind-legs, moaning softly and closing her eyes. It felt phenomenal to finally relax, and the sense of relief was overwhelming... Her marehood had successfully done its royal duty of keeping Twilight's bladder full, and she began to gently rub her back against the covers of her bed as she took in the relief of letting go after so long. She had made it! Just barely, but she made it.

Twilight kept her eyes closed for several seconds, taking the time to catch her breath, before opening them and staring up at the light-pink ceiling. By tomorrow morning her bladder was going to have four entire days worth of pee kept inside of it... just the thought of that was incredible-- that was a really long time! She didn't know if she was going to be able to keep it all in for an entire week like Celestia had asked her to do though... This had easily been the most desperate she had ever gotten since she started holding it in over three days ago, and a week was a really long time. Tomorrow morning was only going to be the forth day, and she was still going to have to hold it in for three more days! She was barely able to get up the stairs and in her bed this time-- how on Equestria was she going to last three more days...? She couldn't just stay in bed all day with the crown hugging her plump outer-lips-- she still had duties to do as Princess Twilight Sparkle. She was also unfortunately unable to just keep the crown on her marehood; she could only use it if she was lying down with her marehood facing up, otherwise it wouldn't stay on, and there was supposedly a reason for that.... If she was standing up, her marehood would be mostly hidden, just like if she was in her bedroom asleep. It wouldn't be out in the open and exposed for everyone to see, as if it were sleeping, so why would it wear a crown? Princesses didn't wear their crowns to sleep... That's why only when it was fully-exposed, like when she was laying down on her back, would it wear its crown. It was a bit of a silly reason, but it was the one given.

Twilight's thoughts soon trailed off to another subject: Just why was Celestia making her hold in her pee for an entire week? She never did get a reason, and she couldn't help but wonder why. Her maximum holding record was usually only around three days, so she was reaching for twice that in this task. Just why would Celestia have her do something so far-fetched..? She did have an advantage this time around though-- her marehood's own personal crown. When she put it on, it gave her a chance to relax, which was something so very important. Still, however, she was having alot of difficulty going about her day-- at least towards the end. She couldn't fathom going through another four days, but she had to. Twilight wasn't the type of pony who would ever want to disappoint Celestia, meaning she was going to try her very best anyway. Surely she could successfully complete her task..

Her mind soon wandered from thoughts to feelings, where the looming pressure down at her lower-abdomen was constantly there. Her bladder had gotten so full already, bulging so far and so visibly... In a way it felt warm and comforting-- warm because of just how much pee was inside, kept right at her body temperature, and comforting, knowing that it was all still there. Her bladder was still full... and that was a good thing.

The alicorn's exhaustion soon caught up with her though, and she levitated the covers over her body and up to her neck. After snuggling in and getting nice and comfortable, she shut off the lights, closing her eyes and nuzzling into her pillow. Tomorrow was going to be an interesting day...

Author's Note

Twilight Sparkle is an amazing and talented pony, I'm sure she'll be fine .3.

An unrevised version of this chapter can be found here: https://pastebin.com/aTySjmue | The writing style is different, so please let me know if there's anything you like about it