//------------------------------//
// Cannot 
// Story: Against All Odds: Derpy's Greatest Misadventure 
// by Mannulus 
//------------------------------//

	Princess Celestia stared through her spyglass once more.  The Red Whatever was approaching at a speed that defied everything she knew about airship structural integrity, and the weird, mammoth machine was following behind it, steadily narrowing the gap.
"It's working, Luna!" she said. "Just don't forget to account for the Coriolis effect."
"What sort of halfwit duffer dost thou take me for?" asked her sister. "'Tis not as though this is the first time I've done this."
"Well, it's just that the moon doesn't have the same sort of rotational forces, and there's no air pressure up there, so..."
"So thou thought I wouldst forget to account for the pressure gradient?" asked Luna. "It hurts that thou hast no faith in me, sister."
"It was just a reminder," said Celestia.
Luna gave a frustrated huff.
"Just make sure the planet doesn't destabilize and plunge into your wretched, orange fireball, please!"
"You're awfully Nightmare Moonish tonight," said Celestia. "You know that?"
"If I was up at noon telling thee how to do thy job, how wouldst thou feel!?"
"To be fair," said Celestia, "I would probably be at least slightly miffed."
Right then, Discord materialized beside the two of them, still wearing his pirate costume.
"Hi," he said. "I made a thing."
"We had assumed," said Luna.
"Mind telling us what it does?" asked Celestia. "Because it looks pretty evil."
"Less evil and more just apathetic to the incalculable suffering it's likely to cause," said Discord.
"That would generally qualify as evil," said Luna.
"I'm not so sure," said Discord. "Is a lion evil when it eats a gazelle, or is it just doing what a lion does?"
Luna paused to think this over, but before she could answer, Celestia spoke.
"What is that machine, Discord?" she asked calmly.
"Probability inverter," said Discord.
Neither Celestia nor Luna spoke.  They both merely stared at Discord for a moment, their mouths wide agape.  They glanced at one another briefly, then back to the draconequus, still not speaking.  They blinked in horror, and shook their heads slightly.
"Yeah, I thought you'd say that," said Discord.
"Sister," said Luna, finally, "dost thou wish to proceed, or shall I do so in thy stead?"
"No, I've got this one," said Celestia, and she cleared her throat.
"WHY WOULD YOU MAKE SOMETHING LIKE THAT!?"
Discord recoiled at Celestia's outburst, which being given in the traditional Royal Canterlot voice, shook the entire battleship to its frame.  The draconequus raised his claws as if to ward away the sheer volume of the sound, and cringed, gritting his teeth.
"Well, I didn't do it, like, yesterday!" he said. "I mean, look at that thing!"
He gestured at the immense, ancient device, still drawing ever nearer.
"That explains nothing!" cried Celestia. "There has never been a time when a probability inverter could have seemed like a good idea!"
"Hey, I just said I made it," said Discord. "I never said it seemed like a good idea."
"In fairness, he did not," said Luna.
Celestia groaned in frustration, and then sighed.
"Discord, I don't care why you made it," she said. "What do we have to do to turn it off?"
"We can't," said Discord. "It reached critical mass well before the Mesozoic era."
"Then how do we destroy it?" asked Luna. "Surely that must be possible."
"I suppose if we fired spells and cannonballs in every direction other than at the machine, there is a vanishingly small chance one of them might hit it," he said. "Other than that, any attempt to directly inflict damage on it is pretty futile, and even what damage we do inflict will only make it more efficient.  Jeez; from how you talked about it, I thought you would know what a probability inverter was."
"I meant by indirect means," said Luna. "Nothing is invincible or immortal.  There is no unstoppable force and there is no immovable object."
"Yes," said Celestia. "Something has to be able to stop even a probability inverter."
"Oh, I've got that covered," said Discord.  "You know Derpy Hooves, Celestia?"
"Oh no," said Celestia, remembering seeing Derpy on the deck of the Red Whatever.
"Oh, you do know her!" said Discord. "Yeah; the little cross-eyed delivery mare I saw at your chamber awhile back.  Well..."
"Did you drag her into this?" asked Celestia.
"Well, I just remembered my friend the Doctor mentioned her once..."
"Not the Doctor!" said Luna.
"...and from everything he said to me..."
"Why does he have to be involved in this!?" moaned Luna.
"...it just really seemed like she'd be the perfect pony..."
"You didn't, said Celestia. "Tell me you didn't."
"...to get into a machine that's proof against competence."
"You did," said Celestia. "Beautiful."
Celestia stepped to the railing and looked out at the approaching machine.
"Tell me she's not already in there."
"I hope she is," said Discord. "She's the only hope we have.  I mean, personally, I'll be fine in a universe of inverse probability, but I have friends who are ponies, you know?"
"Not 'it,'" said Princess Luna.
Discord turned towards her, and his brow furrowed.
"That's cold, you know that?" he said. "No wonder you used to be a villain."
"Listen, Discord," said Celestia. "I just need to know this: what can we do to help Derpy Hooves?"
"Fight robots," said Discord.
"Excuse me?" asked Celestia.
"You heard me," said Discord. "The best thing we can do for Derpy Hooves right now is fight robots.  She'll never make it through the swarm on her own."
"What swarm?" asked Celestia.
"Just keep drawing the machine closer," said Discord. "You'll hear it any second now."
"Hear?" asked Luna.
"It's a noisy swarm," said Discord. "Oh, and kudos on not destabilizing the planet's orbit with all your playing God, and whatnot.  Neat trick."
"Why thank you!" said Luna.
"Wait a moment," said Celestia, turning her head to listen more closely. "What's that sound?"
"That'd be the murderbots," said Discord. "Toodles."
In an instant, he was gone.

As was his custom, Discord suddenly and simply was.  Nopony on the Red Whatever even batted an eye.  Teacup gave a nod, and that was all.
"So, there's a big nasty swarm of clockwork death drones coming," said the Doctor. "Ideas?"
"Battle stations!" shouted Teacup.
"Well, yes," said the Doctor, "that's one."
"Oh boy!" said Discord, rolling up his sleeves and cracking his knuckles. "Finally, an excuse to take everypony down to Discord town!"
He had barely finished his sentence when the swarm of drones poured over the ship.   Cannon fire erupted from below, and all about the deck, pirates leapt, dodged, and took cover.  Soon, the sound of flintlock pistols could be heard, and the smell of burnt powder filled the air.  It was a magnificent display of all such things as one might expect to see in a battle of pony pirates versus plaid, insectoid murder machines.
There were great heroics all around, with pirates swinging from ropes, barrels of powder detonated with carefully fired shots, and the like.  In almost any direction one cared to look, a duel of plaid saw versus flashing cutlass could be seen.  It was such a magnificent display, in fact, that Discord, for all his moments-past bravado, merely stood at the deck railing watching it play out, his face overwhelmed with absolute confusion.
"Discord! What are you doing!?" shouted Teacup, bent backwards over the railing, holding off with her cutlass the strangling chains of a plaid deathbot which had somehow lost its saw blade.
"Nothing," said Discord, not even bothering to help her. "This whole scenario is so impossibly strange I cannot think of a single way to involve myself that seems at all meaningful.  I mean, I could turn into something, I guess, or I  could use something for a weapon that wouldn't typically be used in that way; a frozen tuna, for instance.   I could even make a catapult that shot baskets full of exploding kittens, but, really, would any of that make this any weirder!?"
"Then I will use my own magic," came a heavily trilled, raspy voice from near Discord's side.
He turned to his left to see a griffon clad in the robes of a gypsy.  She was ancient, and had a glass eye that stared straight forward even as the other darted this way and that.  She reached into a pouch at her waist, and produced a handful of dust which she hurled at the plaid drone trying to strangle Teacup.  In a flash, it turned into a swarm of tiny, plaid butterflies, which fluttered away harmlessly.
"You see what I mean!?" cried Discord. "I can do crazy, sure, but at this point, it's just a lateral shift!"
"Oh, quit whining and get involved, already," said the Doctor. "It just always has to be about you, doesn't it?  If Discord's not the center of attention, he just doesn't want to play."
As he spoke, the Doctor had approached from the opposite direction of the gypsy griffon, and was fiddling with a simple tube of what appeared to be polished steel, though there were odd protrusions here and there.
"Think I've just about got this configured," he said, pointing it at a deathbot as it flew by.
There was a brief flash, and the death bot turned from plaid to polka dot.  Less than two seconds later, it burst into flames and crashed to the deck, where it writhed for a moment before falling apart.
"What did you do to it!?" cried Teacup, looking at the ruined machine in an awed state of horror.
"I aligned its metaspacial physiology with a polka dot dimension, thus changing its pattern," said the Doctor. "Entities from pattern dimensions destabilize and spontaneously combust if their patterns are changed.  It's science."
"No, it's not!" shouted Discord.
Before the Doctor could respond, there came the roar of cannons, and the sound of searing energy beams to either side of the ship.  Dozens of ships of the Equestrian Navy had entered the fray, and both princesses were likewise involved.  Killbots exploded port and starboard, and the sky lit up bright as day with the awesome power of Princess Celestia's caffeine-fueled assault.   The moon flickered and brightened, and thousands of whirling discs of silver energy fell like raindrops to shred plaid metal into tiny fragments that tumbled from the sky.  In a show of Princess Luna's honed control of her magic, not one of them even nearly struck the Red Whatever or any of the naval vessels.
"Cap'n," came a gruff voice, and Discord turned to see Pegwing standing beside Teacup.
"Yes, Pegwing?" asked Teacup.
"Didn't we almost fight one-a them Princesses one time?"
"Yes," said Teacup. "We very nearly did, Pegwing."
"I'm glad that didn't happen," he said.
"As am I," said Teacup. "Also, quite glad to see you're up from your nap.  Would you please dispense with the remainder of these plaid miscreants cluttering up the deck of my ship?"
There were still several dozen of the plaid murderbots assaulting the pirates, and Teacup indicated them with a hoof.
"Aye," said Pegwing.
Without a further word and with no hesitation, Pegwing drew his cutlass, and charged forward.  He buried his cutlass in the body of the first killbot he reached, and vaulting off of it, took another by its chain tail with his teeth.  He whirled it around, slamming it into another of the machines so that both were left shattered.  Another came in towards him then, but he quickly snatched the remains of his previous victim's chain tail to his right, and wound it around his foreleg by waving it in a circular motion.  Just as the robot arrived to swing forward its wicked saw blade tail, he raised his foreleg, now wrapped in the chain, and fended off its attack by using the chain as a shield.
A shower of sparks flew over Pegwing's head as the blade ground into his shield of plaid chain.  Showing no sign of intimidation, the pegasus thrust his left hoof forward, and stopped the saw blade cold with his own horseshoe.  The sudden backlash spun the drone around on the axis of its own tail blade, and sent it flying straight down into the deck, shattering it completely. Pegwing reached down, and tore the thing's tail away from its body.
As soon as he lifted his head, he was whirling dervish of destruction, spinning across the deck.  He slaughtered his foes wherever they were found, splitting them cleanly at single passes of his plaid saw blade flail.
"This is the most violent thing I think I've ever seen," said Discord, his eyes dazed and distant.  "That means... it's maybe the most violent thing that's ever happened... and I'm here for it... I feel somehow privileged."
"Good, old Pegwing," said Teacup, smiling with satisfaction.
"I quit," said Discord. "I'm gonna go lie down."

Celestia soared toward the engine, the sky around her alight with the spectacle of the strange battle.  She craned her neck this way and that, searching all the while for any sign of Derpy Hooves.  The thought occurred to her that the pegasus might already be dead, struck from the sky and fallen into the sea far below, never to be found.  The idea made her heart skip a beat and sent a chill racing down her spine.
She had been searching for several minutes when at last she beheld something strange on the side of the enormous contraption:  A gear that was not turning.  She flew in for a closer look, and to her great relief, she saw Derpy Hooves.  The giant gear was oriented horizontally, and Derpy rested on its side, her forelegs splayed out and her head hung low, so that she stared downward between her hooves.  Celestia landed heavily on the gear before her, and the startled pegasus recoiled with a shriek.
"Derpy Hooves!" said Celestia. "I was worried you were dead!"
"I think I should be," said Derpy. "There were so many of them..."
Celestia looked around, and realized that pieces of the plaid defense drones were scattered all over the huge gear, many of them stuck in its teeth and axle.  Likely it was these pieces of debris that had stopped its motion.   The teeth of the gears next to it ground and groaned, jerking repeatedly in an effort to restart their motion, and several huge pistons and flywheels were likewise stalled and unable to move.  They shrieked, groaned, and belched steam, some of them glowing red hot from their intense friction and warping even as they continued to attempt to turn and oscillate.
"What happened?" asked Celestia.
She turned briefly to blast a plaid turret that was slowly tracking their direction.  The beam completely vaporized the weapon, leaving only a smoldering stump where it had been.  Derpy yelped in surprise, and rubbed at her eyes where the intense light had momentarily blinded her.
Still the pegasus did not lift her eyes to the Princess.
"Sorry," said Celestia.
"It's okay," said Derpy, staring downward. "I can still see... mostly."
"Did you destroy all these things?" asked Celestia, waving a hoof around at the many chunks of plaid destruction.
"No," said Derpy. "There were so many trying to get me all at once that they cut each other up.  They all tangled into a big ball with me at the center, and it landed here."
Derpy Hooves should be dead.  Celestia knew it beyond a shadow of a doubt.  The gear they were standing on was a titanic piece of iron, covered in gigantic engravings and scrollwork.  It was at least half a mile wide, and over half its surface was covered in ruined deathbots.  For Derpy to have survived the attack of so many in the manner she had described was patently impossible, but she had done so nonetheless.  As much as it pained Celestia to admit it, Discord was right:  Derpy Hooves was the only pony who had any chance of stopping this machine.
"Listen to me, Derpy Hooves," said Celestia. "I need you... No; everypony needs you.  You have to find a way inside this machine, and you have to stop it.  I legitimately do not believe that anypony else in the entire world can do it --  Not even Luna, Twilight Sparkle, or even myself.  This may be the very reason you were born... or it may just be a turn of fate.  Either way, you have to be the one to do this."
"I know that," said Derpy, stilll staring down at her shaking hooves.
Celestia stepped forward and tilted her head in confusion.
"You do?" she asked, legitimately surprised that Derpy had made no attempt to talk her way out of the mission.
"Yeah," said Derpy, "I do, and it freaks me out."
At last, the pegasus looked up.  Celestia was surprised to see that she had apparently been crying for some time.  There were tears in her eyes, and a very inelegant stream of mucous running from one of her nostrils.  She sniffled, and forced a smile.  Despite her efforts to appear courageous, however, tears continued to flow, and her voice cracked several times as she spoke.
"Princess," she said, "I don't believe in myself; I never have.  Even when I was little, I was always scared to try anything... even things I thought I'd really, really like to do.  I always just knew somehow I'd fail, so why risk it?  But lately... There's been times... a lot of times... when I was sure I couldn't do something, but somehow I did.  But I didn't think I could do it -- not even once.  Every single time, I was sure I just couldn't, but I did it anyway.  That's why I know it has to be me; why I know I have to try.  Because I look at this machine, and I'm more sure than I've ever been in my entire life that I cannot do this."
Derpy said not a further word, nor did she wait for one from the Princess.  She merely turned and ran towards one of the jammed pistons.  The shaft that drove its head was narrow enough that it left a wide gap around its base, and the pegasus leapt into this opening, disappearing from Celestia's sight.  The Princess stood for a moment, staring after her in astonishment.
Dear Princess Celestia, thought the alicorn, and with that, she took off to rejoin the battle.