Rarity prided herself on her commitment to cleanliness. She took great care in making sure she looked the part of a pristine and refined mare from the moment she woke up, the result of hours spent making sure everywhere from the tip of her mane down to the soles of her hooves was pristine and free of any dirt of blemishes that could ruin her finely crafted image.
This commitment didn't just stop at the physical either, as just about every part of her life from the way she spoke and carried herself, to the freshly cleaned look of her many boutiques shared in this level of cleanliness. Ask any pony with even a passing knowledge of Rarity and inevitably they would remark on how much of a shining beacon to cleanliness she really was, almost to the point of bordering on obsessions. Sure, there had been moments in her life where she had needed to get “down and dirty” in the dirt and mud, but a nice, long shower always cleared that right away.
And yet, Rarity knew that despite the image she projected onto the world, deep down... she was a very, very dirty mare. Possibly the dirtiest mare in all of Equestria even, and it was only behind the locked door of her boutique's basement back in Ponyville that she could let loose and be the filthy mare she really was.
This was the main thing on Rarity's mind as she strolled into her boutique one night after a long and exhausting day. Part of her wanted to just head upstairs and take a well deserved nap, but the excitement of what else she had planned very quickly overrode that thought as she locked the door behind her and practically pranced for the door to the basement.
As she threw open the door, she was met with several racks of dresses and clothes from her previous sets, having designated the basement as storage long ago. Weaving though and around the multitudes of past fashion lines, Rarity finally came upon her true destination: a seemingly benign looking door at the far back of the basement, largely hidden behind the wall of clothes down here. This door was very special though, as it had been fitted with a lock that would respond only to Rarity's unique magical signature to ensure that she was the only pony with the key.
Illuminating her horn, Rarity was positively giddy with building excitement as the sound of the lock clicking open reached her ears. Wasting little time, Rarity stepped inside the mysterious room and shut the door behind her, which locked again with an audible click.
On first glance the room itself wouldn't appear to be all that noteworthy, seemingly being just a sparsely furnished guest room with a bed, a night-side table with a lamp on it, and a small closet. There wasn't even any carpeting within the room, with the floor instead being tiling that would have looked more natural within a bathroom.
Strolling up to the closet door, Rarity pulled it open and began rummaging inside for everything she would need. After several moments of searching, she had finally located everything she needed and levitated them over to the bed to prepare.
The first item in question appeared at first to be just a blue rubber hot water bottle, which would make the rubber tubing and nozzle connected to it seem very out of place, as would the container of solution nearby and the IV stand set up next to the bed. For this was actually an enema bag, one Rarity had much experience with using. Next to that were two small containers labelled “Rash Cream” and “Lubricant” respectively. But if these items didn't already raise some eyebrows, then the next two would have definitely resulted in some questions.
Lying atop the bed was a large baby blue rectangle, one with a noticeable plastic sheen to it. Next to that appeared to be a set of clear plastic and watertight undergarments to be worn along with the other object. The first object was unmistakably an adult sized diaper, one that made Rarity recall the packaging saying it could contain, “Even the biggest of accidents!”
Rarity smiled at the though. I'll be the judge of that.
As she hooked the enema bag up to the IV stand and began to pour in the solution, she winced as a loud grumble emanated from her belly and a fullness in her bowels grew ever more urgent. Rarity had made sure to eat a large meal in preparation for this moment, and now her body was making it very clear how much she desperately needed to relieve herself. She ignored it, however, as she finished setting up the enema bag and turned her attention onto the diaper still sitting atop the bed. Unfolding the diaper with a bevy of loud crinkling sounds, she set it down on the floor nearby before then unscrewing the container of rash cream and applying an even layer of cream to her rectum and mare bits. Once she was satisfied, she unscrewed the container of lubricant and gathered up a small ball of it in her magic.
The first few times she had done this she had needed the aid of a mirror, but now Rarity was experienced enough to levitate the ball of lubricant up to her anus and gently lube it up, only wincing slightly as the cold liquid touched her warm flesh.
With everything prepared, it was almost time for the main event.
Licking her lips, Rarity positioned herself over the open diaper and carefully floated the nozzled end of the enema bag over, inserting it directly into her hole. “Ahhh...” she moaned as the nozzle slipped effortlessly inside her. Once it was fully inserted, a quick shake of the bag caused the solution inside to rush down the rubber tube and into her bowels. If Rarity had felt full before, the rush of solution pouring into her was making her picture a balloon being inflated more and more until it finally bursts, but this sensation only served to excite her even more as the seconds slowly ticked by.
After several slow moments, the bag finally ran dry. The clock was truly running now, as Rarity quickly removed the nozzle and plopped herself down onto the diaper and pulled up the front of the diaper as she quickly worked to tape itself onto her. She still took care to make sure it was secure enough that it wouldn't leak, but the quickly growing fullness in her abdomen made it clear that she didn't have long. Once she was sure the diaper was tape up tight enough she stood back up and grabbed the plastic pants off the bed and yanked them up her legs until they sat securely onto her thickly diapered rear.
And now... she waited.
Minutes felt like hours as she felt the fullness of her belly begin to settle. She still felt like she might explode at any moment, but it didn't feel as urgent as it had a moment before. Her belly grumbled again as another minute passed with nothing happening. And then...
“Oh!” Rarity gasped as the fullness from before suddenly returned, even more urgent and pleading for release than before. But still Rarity held on, wishing to prolong and savour this moment for as long as possible. Her eyes clamped shut as the bloating in her bowels began to border on the painful, and she knew in her heart that she was only seconds away from losing the battle with her bowels.
In that moment, Rarity's tail flagged up and she did the only thing she could: Push.
Like a mudslide cascading down the side of a mountain, a torrent of manure and dung poured out of Rarity like water from a broken faucet. The unmistakable stench of fresh feces began to fill the room as Rarity's diaper began to bulge and sag as it tried to contain the rapid flood of feces, as the plastic pants stretched and stretched to hold in the quickly expanding mass. Never in her life could Rarity have imagined she was even capable of producing the volume of horrid sludge that was currently pouring out of her, and it was still going without an end in sight!
As several moments passed and her diaper sagged low enough to touch the floor, Rarity finally felt the torrent begin to slow down. A few more pushes helped to move along whatever she had left inside her as her bowels finally voided themselves completely. As her tail lowered back down over her diapered rear. Rarity was left with her butt in the air as her upper half braced against the ground, breathing heavily in the fecal stench that was radiating out from her utterly destroyed diaper.
Anyone else in this situation would have likely begin to retch and gag at the stench in the air, but not Rarity. In fact, Rarity reveled in the huge mess she had just made into her diapers, her arousal building with each stench filled breath she took. With a wiggle of her behind, Rarity slammed her sagging, mess filled diaper onto the floor, feeling it squish and press against her body as she flopped over onto her back.
Rarity was in smelly heaven as her front hooves pressed deeply into the front of her messy diaper, feeling it rub against her with each thrust of her body as she rubbed harder and faster. She panted for breath as she felt pleasure course though her body, filling her with excitement that was virtually undesirable. Back and forth she rubbed against the messy contents of her diaper, feeling her excitement grow and grow at how much of a dirty!
Smelly!
Disgusting!
Filthy!
Messy diaper lover she was!
“AAAAAAAHHHH!”
With a thunderous cry, Rarity orgasmed harder than she could ever remember. Her eyes rolled back into her head for a moment from sheer, unimaginable bliss as she rode the lasting aftershocks for what felt like an eternity. With great effort, Rarity managed to drag her post-orgasm self over the bed and lift herself up and onto it. She didn't even bother getting under the covers as she let her still rancid diaper air out. A slight humming sound filled the air as vents in the walls began to siphon the smell away and into open air, but Rarity hardly noticed it as she felt herself drifting off to sleep, now completely spent from such a powerful experience as this one.
She knew that in the morning she would need to go through the arduous tasks of disposing of her used diaper and cleaning away any and all trace leftover from her time spent in here... but at the moment that was Future Rarity's problem, while Present Rarity was content in letting herself drift off to dreamland in nothing but her dirty, mess filled diaper.