Ditzy 'Derpy' Doo was never a normal pony. An accident that occurred when she was just a filly gave her wall-eyes, which for a pegasus, is a problem. On multiple occasions she has caused problems for other ponies, and on one occasion, a huge benefit for ponies everywhere.

It all started in the middle of summer, when after an unfortunate incident where Derpy bumped into a delivery pony's truck and caused furniture to fall out onto some poor pony below, she was grounded by the Mayor of Ponyville from flying. Not that she cared too much about not flying, as walking was less dangerous to her with her wall-eyes. It's been a week since she did that, and even though she has seen the pony she accidentally hurt around town, thankfully she didn't recognize her any of the times she encountered her.

Derpy was walking down the main street of town that fateful day, wondering what she would do. Her only friend Lyra was out of town that day, so Derpy was by herself that day. She mainly wondered around town, looking at the various items that were in stock at the market, before heading over to the Sugar Cube Corner.
Pinkie Pie was her usual upbeat self, working happily in the kitchen making cupcakes. She noticed Derpy walking into the shop.
"Ain't it an absolutely-positively-wonderful-spectacular day, Ditzy Doo?" Said Pinkie, who was putting cupcakes into the oven.
"Pinkie, you really need to stop borrowing phrases from the Apple clan. It really isn't good for you." Derpy replied.
"I really don't CARE about my grammar, as long as my cupcakes taste SPECTACULAR! Mr. and Mrs. Cake are giving me good pay for this job, which allows me to buy all SORTS of crazy ingredients to put in my cupcakes!"
"I really don't care what kind of ingredients you use in your cupcakes. Can I have a dozen?" Derpy was getting impatient at Pinkie Pie, who was starting to make her angry.
"Okey-dokey! Coming right up!"
Pinkie Pie gave Derpy a bag of a dozen cupcakes, fresh from the oven.
"Thanks Pinkie, you're the best." Derpy said.

Derpy turned around from the counter and walked out the door. Or at least, she almost did. She immediately banged into the wall, missing the door by a foot, and leaving her with a small lump on her forehead.
"Ow, stupid wall-eyes" Derpy muttered under her breath. Walking out the door without bumping into anything this time, she noticed that the sun was setting.
"That's strange, the clock said it was 3 when I got up from my nap. It wouldn't be the first time it's happened for me, though, as I've misread the clock due to my wall-eyes before."

Walking down main-street the usual way she went home, which was through the market that was now closed due to it being sun-down.
Suddenly, a loud crashing noise came from the alley to her right. This was strange, as nopony was there, until
a brown pony came charging through, with a curious cutie mark the shape of an hourglass. He had brown fur, and a darker brown mane.
"RUN!" He yelled, with an accent that sounded like he came from Trottingham.
Derpy didn't know what was going on for a brief moment, which ended quite suddenly something that looked like an upside-down ice-cream cone with studs all over it, a rounded top, and a few sticks that had appendages on the end.
"EXTERMINATE THE DOCTOR!" It said, shortly before a blue beam fired from one of the sticks and half-destroyed a cart left out by it's owner.
"WHAT IN BLAZES IS GOING ON OUT THERE?" Said a unicorn who popped her head out from a window, who had her mane combed, shortly before screaming after seeing the creature, and quickly shut the window and shutters with her magic.

"CATCH THIS!" Yelled the brown pony, suddenly throwing a blue ball at Derpy.