Derpy sighed as she loaded the last envelop into her parcel. Her clumsiness had cause another delivery mishap, and so her boss had her on the long distance deliveries that nopony else wanted to do as punishment. Even worse, she was still expected to make these deliveries in a "timely manner". Considering how far she had to fly to even reach her destination, she reasoned that she'd have to fly almost twice as fast as she normally does without any stops. When she brought this up to her boss, he simply reminded her that it was entirely her own fault that she was stuck with this and gave her no concessions. If she didn't need the bits so badly, she would've quit this job ages ago.

On the bright side, being a delivery pony meant that she got to hear about all sorts of different products that she wouldn't have otherwise. Since she usually got stuck with the difficult or just strange deliveries as a result of her mishaps, she talked to ponies about several different items that she probably wouldn't have found on the standard market. Surprisingly, one of the more common ones she delivered was special diapers for adult mares, an item she purchased herself for times such as this. As long as she packed some snacks, she should be able to make her trip without stopping for anything.

Confident that she was set, she sprung from the post office balcony and began her journey out to... wait, where was she going again? She fumbled through her parcel to pull out one of the envelopes and check the address. Vanhoover, that was it! She deftly turned around to fly north and set off for her journey.

Derpy quickly realized that she probably should've used the bathroom before she left. It was about ten minutes before she felt her bladder start to ache, and while she knew her diaper could hold it if she just used it now, she was looking at a 5-7 hour flight depending on how fast she flew, and she wasn't sure how well it would hold up by the end of her trip. Not that she had much choice; trying to hold her pee while already exerting herself flying faster than ever was an impossible task.

Not even a few more minutes passed before she gave out and pissed her diaper. The sudden and intense warmth flooding her nether regions made her flight falter for a brief moment; she hadn't actually tried this before, so the sensation was quite the shock. Not to mention the fact that it felt amazing. If it wasn't for the fact that she had to make sure it lasted her whole journey, she probably would've gone out of her way to pee as much as possible.

Unfortunately, that lingering excitement made it even more difficult to focus on her flying. It mostly went away within a few moments, but she still felt a subtle tingling in her groin; she could only hope that it didn't get worse the more she had to use her diaper.

The hours passed, a couple of snacks and water bottles had gone away, and Derpy took a small dip beneath the clouds to appreciate the view before gliding back above the sky's fluffy pillows. It was generally advised for pegasi to fly so high on longer travels so as to make sure they didn't collide with others who usually used the space between towns to practice aerial stunts and other high speed maneuvers. Derpy didn't mind, as it also saved her from the possibilty of someone catching her peeing herself.

If only that was the only thing she had to worry about. She still had another two hours to fly, but by this time she was pretty sure her diaper was already soaked front to back. The wetness wrapping from her ass straight between her thighs made it even more difficult to focus, and she could feel another wave building up in her bladder. That and a growing pressure from the other end, something that Derpy was hoping wouldn't escape before she landed. A piss-soaked diaper is one thing to try and hide, but there would be no way she could conceal it if it was full of something else.

The best she could do was take some napkins she had in her parcel (can never be too tidy) and gently stick them down her diaper. They got soaked pretty quickly, and the touch against her pussy lips wasn't quelling her excitement, but she hoped they would provide enough absorbance that she wouldn't start leaking. As for the other problem, she just had to hope she could make it to Vanhoover in time, though the exhaustion coursing through her body already made that difficult to believe.

Another hour passed and another torrent of pee had escaped her body, the napkins working just well enough to prevent a massive leak, though some of it still dripped into her jeans; hopefully she could play it off as just a little rain.
Her situation was growing worse by the minute as she juggled between trying to maintain even her average flight speed, the pressure knocking on her back door, the noticeable excitement that wouldn't go away anymore, and the nagging feeling that she still needed to pee even more.

Her body was becoming more and more desperate for any kind of relief, and despite her flying making it harder for her to hold anything in, it was also the only thing distracting her from just how bad it was getting. She also knew that if she gave in, it would be near impossible to reach Vanhoover in time; she wasn't entirely sure but she imagined trying to fly with a filled diaper wasn't exactly conducive to getting somewhere quickly.

So, she pressed on, her perception of the time left coming down to each minute that passed. Was her destination close to the outskirts of the city, or did she have even further to travel? Was she delivering straight to a mailbox, or did she have to hand the letters over in person? Just who was she delivering to? Was everything going to the same address or did she have several stops? A lot of questions she probably should've had answered before she left, but it was a welcome deviation for her mind to focus on, even if a lot of the possibilities would ultimately make things more difficult for her in the end.

Just to be sure that she was timing herself correctly, she dipped down below the clouds once again. In the distance, she was able to spot some of Vanhoover's larger buildings. She was almost there! If only her wings weren't so fatigued she'd try and make a final sprint to the city, but by now her body's energy was spent almost entirely on holding both her piss and shit in. She could tell she was fighting a losing battle, so she needed some way to either get to the city quicker or alleviate her bathroom needs.

Her bladder wasn't waiting, finally giving out and soaking what little her diaper could hold before painting her jeans with a dark stain. Feeling the heat rush down her pant legs was enough to stumble her flight once again, and with no energy left to pick herself back up, she knew she had to land. She carefully glided through the forest that surrounded her destination, lightly bumping against a few trees before touching down on the ground. Her excitement had come back in full, and what little strength she had holding back the log poking at her anus was being drawn away by her own desires. If pissing herself felt so good, surely...

The pleasure started to win out against her practicality, her hand shifting between her legs to press her soaked jeans and diaper against her swollen pussy lips. The wet warmth sent electric jolts coursing through her body, encouraging her to press and rub even harder. She knew she still had those deliveries to make, but she just wanted to let go so badly.

So she did. With one swift motion she knelt forward and finally released the large turd that had been begging to be let loose for hours. It forcefully slithered its way out from between her ass cheeks, piling up and filling out what little room was still left in the puffy garment. It felt even better than Derpy could've imagined, and she still had more to push out. She pulled her hand away from her jeans and shoved it straight down her diaper, pushing two of her fingers into her pussy as her shit pillowed her diaper out. She thrust her fingers vigorously, desperate to bring herself to a roaring climax.

Within seconds, the last of her poop tapered out from her ass and her orgasm hit like a freight train, coating her hand and her diaper in a large spray of viscous cum. She collapsed forward, riding her climax out as she slipped her fingers out of her pussy and grazed her fingertips against the soiled padding of her diaper. All she had to worry about now was finding a place to clean herself up, make those deliveries, and...

Fly back home. For several hours.

Oh well, she thought. Her jeans were soiled already, what's a little more to add to it?

Author's Note

I've been debating on if I wanted to do sequels for some of the chapters here. Both Fluttershy's and Moondancer's have perfect setups to follow on, but I also want to focus on other characters and what new scenarios that could bring about instead of recycling ones I've already done chapters for. What do you guys think?