One day, Derpy was on her way to her job at the post office when she suddenly spontaneously combusted. “AHHHHHHHHH!” she screamed, and started flying out of control around Ponyville, her flames setting buildings all over the town on fire and causing many panicked citizens to flee their homes.
“Sorry!” she shouted, and then continued screaming, “AHHHHHHHHH!” This went on for a bit longer until she finally realized that the fire wasn't actually burning her for some reason. (In fact, it felt surprisingly warm and cozy.) Unfortunately, the same couldn’t be said for anything else.
Her heart rate slowly returning to normal and her mind no longer in panic mode, she looked down at the town and all the destruction she had caused. “Oh, no!” she said in open-mouthed horror, raising her hooves to her face. “This is terrible.” She had to do something!
Flying down to the chaos below, she found a bucket that someone had left lying near their house. Surely they wouldn’t mind if she borrowed it under these circumstances. Taking it, she started to fly off to go fill it with water.
“Hey, give back my bucket!” a pony shouted from behind her. “I need it to save my house!” His house was on fire.
“Uh…sorry, sir,” Derpy said, flying back toward where she had gotten it. “I was just going to get some water to help.” She tried to hand him the bucket, but he backed away slowly, his face twisted in terror and confusion, then turned and ran. Derpy looked down and saw that the bucket was on fire.
“How is that even possible?” she wondered. It was made of metal, and as she carefully set it back on the ground, it began to melt. Then the ground caught on fire.
Derpy gasped, then tried blowing on the ground. This only spread the fire more quickly.
Suddenly, from a distance, she heard a shout. “She started this! Get her!” And then a whole crowd of ponies came running toward her from around a corner.
“I’ve got to get out of here!” Derpy thought to herself, sad that she couldn’t help but not wanting to make things any worse than she already had. She flew up and away before any of the ponies could catch up. Luckily, they were all Earth ponies.
“Now what?” she wondered, flying haphazardly as she looked around and tried to decide where to go. She obviously couldn’t go to her job in this state, and she had a feeling that ponies wouldn’t be particularly happy to get the mail from her right now, anyway. Suddenly, she bumped into something.
“Oof,” she said involuntarily, then looked at what she had hit. “Oh, no!” It was Twilight’s castle, and she had just set it on fire.
Screaming in horror, she fled toward the Everfree Forest. Surely she couldn’t hurt anypony there. Except maybe Zecora, she supposed, but she’d head well away from where Zecora lived just to be safe.
Upon reaching the edge of the Forest, she hesitated. Now that she thought about it, maybe going there wasn’t such a good idea. After all, wood was flammable (especially in comparison to a metal bucket) and she didn’t want to be responsible for burning down the Forest, too.
So on second thought, she flew up to a nearby cloud, deciding to hang out there until the flames burned out. She didn’t know what was going on, but surely it would go away soon. Right?
She landed on the cloud and it instantly caught on fire. Fiery rain began to fall down to the Everfree Forest, creating a quickly-spreading blaze of disaster. Derpy's eyes widened and she fainted in shock.
When she woke up, the flames around her were even more intense, but she still felt fine. Physically, anyway. Mentally, not so much, especially after looking around at the devastation she had caused. Ponyville citizens’ homes and Everfree trees alike were now nothing but charred black husks as far as she could see. She must have been sleeping for hours as the blaze continued, and now as she looked around, everything was engulfed in flame.
She left the cloud and flew all over the remains of Ponyville, now a flaming ghost town. She broke down in tears as she wondered whether that might literally be the case. There was no one to be seen, and could they have even escaped this? Even Twilight’s castle was destroyed.
Sobbing uncontrollably, she began flying toward Canterlot, her wings now shooting off bolts of flame with every flap. Celestia and Luna seemed like the only hope now. Maybe they would know what was going on; maybe they could stop this. Time travel was a thing, right? Maybe everypony could still be saved. That thought was the only thing that kept her going as she continued on her flight.
After a while, she reached Canterlot, only barely ahead of the continually advancing flames down on the ground. The emergency force field around the city had already been activated. “Please let me in! I need to talk to Celestia and Luna!” Derpy shouted down to the guard, who was standly nervously in front of the only entrance. Her words came out as a jet of flame aimed directly at him, and he caught on fire. Panicked, he opened the entrance and ran inside, closing it behind himself before Derpy could enter.
As she watched, he zigged and zagged back and forth, setting other objects inside the force field ablaze. Within minutes, it had spread to the city proper and was heading toward the castle.
Derpy couldn’t believe it. Celestia and Luna were her last hope, and now, assuming they were in there, their own security mechanism was holding them captive. If they didn’t do something in time, there would be no escape. Bashing herself on the force field as close to the castle as she could get from outside, she yelled, hoping somepony might still hear her. The force field caught on fire and the blaze spread in all directions almost instantaneously. A moment later, it failed and the flame rained down onto Canterlot all at once.
Derpy hovered open-mouthed as she surveyed what had just happened. Without Celestia and Luna, there was now only one thing she could do.
Looking at the Sun, she began what she was sure would be her final flight. It was a long way away, but she had to make it. Surely the Sun would overpower whatever was happening to her, and even if it couldn’t stop the spread already occurring on the ground, hopefully somepony would be able to before it got too far. Maybe Discord? It couldn't have reached the Crystal Empire or Saddle Arabia yet, so there might still be time. She had to sacrifice herself to avoid making things even worse.
A long, long time later, long enough that she completely lost track, she reached the Sun. She had sadly noted long before she got there that it was no longer moving in the sky, indicating that a horrible fate must indeed have befallen Celestia. Bracing herself for the end, she flew as fast as she could into its massive blazing form.
Nothing happened. Whatever was protecting her from the fire around her must somehow have been protecting her from the Sun as well. The entire journey had been pointless. After reaching what she felt must be the center, she turned around and tried to leave. As she reached the edge, she tried to fly back out, but the flames around her remained attached to the Sun and she was pulled backward, finding herself moving the entire celestial body ever so slightly.
Pulling again, she tried to escape, but once again, she did nothing but pull the Sun slightly toward the direction she was trying to go. Without Celestia holding it in place (something which she had always constantly done on some subconscious level), it was more mobile than it should have been.
Pulling one more time, she finally broke away. The flames still surrounded her. As Derpy got her bearings, the Sun suddenly pitched forward with an audible creak. As she watched in horror, it came completely free of its orbit and began to fall toward Equestria at a breakneck pace.
“NOOOOOOOOOOOOO!” Derpy screamed, flying after it. She had never been one of the fastest fliers in her flight school, but at that moment she flew like she had never flown before. Creating multiple sonic rainbooms behind herself, she managed to catch up to the Sun and re-enter it, the flames surrounding her re-attaching to the Sun’s own.
With more effort than she had ever given to anything, Derpy flew upward, trying heroically to pull the Sun back along with her. It slowed for a moment and then the flames surrounding her detached and it continued to fall. Bursting into tears once again, Derpy’s resolve finally broke and she could only watch as it crashed all the way down to Equestria, engulfing not only the entire country, but the entire planet. As the flames began to extend even beyond the planet, it was clear that this was truly the end.
