Ditzy "Derpy Hooves" Doo was Ponyville's mailmare. She was wall-eyed, and the malady was evident even at a distance. Many ponies wondered how she managed to fly with her vision impaired, let alone deliver Ponyville's mail. In fact, some ponies had privately concluded that Ditzy was something of a charity case, and had been given the position of Ponyville Mailmare out of pity or a sense of duty to those less fortunate.
The truth was quite the opposite. Derpy eyes be damned, Ditzy Doo was the fastest mailmare in all of Equestria, and she regularly received tantalizing offers of employment from other branches of the Equestrian Postal Service in larger cities like Canterlot and Manehattan. They offered a higher salary, highlighted the amazing, picturesque aerial views she'd encounter as a big-city mailmare, and even insisted they'd buy her a home if she agreed to transfer.
But Ditzy turned them all down. She loved Ponyville and its inhabitants, even though some of those inhabitants did not know just how lucky they were to have her. She loved flying over Sweet Apple Acres, taking in row after row of immaculate apple trees. She loved getting a split-second glimpse into the Carousel Boutique to see what marvelous things the owner was making. She never grew tired of skimming the edge of the Everfree Forest as she delivered mail on the outskirts of Ponyville. She adored the smell of Sugarcube Corner in the morning, while Mr. and Mrs. Cake made huge batches of sweets to last them through the day. She even loved the quiet dignity of the library set into a tree, which doubled as the home of a kind and wise unicorn named Twilight Sparkle.
Ditzy knew of Twilight Sparkle's kindness first-hand. Ditzy's daughter, Dinky, was a unicorn like Twilight, and had been fortunate enough to receive private lessons in magic from the purplish mare, who had herself studied under the one and only Princess Celestia. Ditzy wanted desperately to find someone who could help her daughter in ways she could not (as she was a Pegasus pony, she had no knowledge of magic), and Twilight Sparkle had shown herself to be a wonderful teacher.
In addition to teaching, the unicorn was also involved in a number of research projects which were based in Canterlot. One such project was codenamed "Pony Express." The Pony Express was a machine designed to enable earth ponies and unicorns to deliver mail at a speed comparable to Pegasus travel, while carrying more mail than a single pony could manage alone. Twilight had asked Ditzy a few questions regarding the design of such a machine, so that the unicorn engineers developing it could tailor it to the job of mail delivery. She had been asked to estimate how fast she could travel, in feet per second, and how long she normally paused at a mailbox or door. Curiously, she'd also been asked to estimate how many g-forces she could comfortably withstand and how comfortable she was sitting for long periods of time.
Finally, Twilight asked if she would be willing to pilot the first prototype machine and provide feedback to the engineers so that they could improve the design. Ditzy had happily agreed.
Yesterday, when walking Dinky back home after her magic lessons, Twilight had informed Ditzy that the prototype Pony Express was ready for testing. "The engineers in Canterlot are excited to see what you can do with the new machine. They have a theory that Pegasus ponies are able to think faster than unicorns and earth ponies, since flying requires quick decisions." Twilight frowned slightly. "Actually, they said they were only willing to trust the first test run to someone as fast as you. The other candidate was Rainbow Dash, but she lost interest the moment they explained that it didn't fly."
Dinky was busy levitating small objects with her unicorn magic, while Twilight showed Ditzy the prototype. It was sleek and long, with two lights in front, framing the word "SUPONU." It had four shiny wheels, and two little mirrors, which Twilight explained allowed for reverse operation when necessary. Ditzy looked the thing over, and decided that it looked… fast. Not just fast, maybe sort of… mean. Like it wasn't afraid of anything.
Twilight reared up on her hind legs and placed her hooves through one of the open windows, where she pointed out the machine's various buttons and levers, and explained how to make it go, stop, and turn.
"Alright, any questions, Ditzy?" Twilight asked with a smile.
Ditzy shook her head. "Nope. I think I'll figure it out. I probably won't set any records my first day with it, but maybe I'll get better over time."
"I'm sure you'll pick it up quickly." Twilight laughed. The purple unicorn said goodbye to Dinky and set out for her library.
Ditzy trotted around the huge contraption once more before she and Dinky went inside for the night. Tomorrow morning, she'd do her route on the ground for the first time.
Dinky had pleaded for the opportunity to join her mother for the maiden voyage of the Pony Express, and Ditzy had initially been hesitant, citing the fact that the machine might break. However, Dinky pointed out that unicorn magic might come in handy when handling a unicorn-made device. Between that and her general cuteness, she had convinced her mother to bring her along.
When Ditzy pressed the button that started the strange machine, it gave a deafening growl. She stuck her tongue out as she concentrated on hitting the pedals near her hind legs in the correct sequence, and then she mashed the one Twilight had called the accelerator. The SUPONU kicked up a great cloud of dust and was off with a deafening roar.
Twilight Sparkle sipped her morning cup of tea, looking out her bedroom window as she waited for her brain to warm up. Over time, she became aware of a strange sound. The normal sounds of morning were present – the chirping of the birds, the rustling of the trees in the breeze – but this was something new. It started out very soft, but quickly grew louder. By the time she clambered down the steps and out the front door, it was very close, and a moment later, the SUPONU slid around the library, making a huge racket and stirring up huge clouds of dust. The back of the vehicle swung around unexpectedly, and it came to a stop perfectly perpendicular to Twilight, who had dropped her tea.
Ditzy Doo stuck her head out the window, offering a mouthful of letters wrapped in a smile. Twilight composed herself enough to take the letters with her magic. Now that her mouth was free, Ditzy spoke. "This thing's pretty fast, Twilight. I'll let you know later if I break my record today. Bye!" With that, she gave a spastic wave of her hoof and lurched away.
Faintly, over the din of the engine, Twilight heard Dinky Doo shout something to her mother. "Make it do a circle again!" The car switched direction, the rear swinging out in a graceful arc as it spat chunks of earth and grass into the air while Ditzy tore a donut around Twilight's home. Twilight got a tiny glimpse of Ditzy as she whipped by again, biting her tongue in concentration, while Dinky stuck one hoof out the window and flailed it wildly, grinning and cheering like Spike in a jewelry store.
"Was it designed to go sideways?" Twilight wondered aloud.