Equestria
Jason was dimly aware of his surroundings as he slipped in and out of consciousness. He was warm, he knew that much. That's good. He thought to himself. Warm is good. Slowly, it registered to him that wind was whipping past his face. He opened his eyes to see what was going on, and screamed in terror.
Far, far below him, he saw fields and mountains laid out as far as he could see. Directly below him, an especially large mountain jutted out of the earth. He began to panic, and spread his arms and legs out as far as they would go in a futile attempt to slow himself down by way of air resistance. This failing, Jason descended into full-blown panic mode. He flailed his limbs around madly and began hyperventilating, failing to notice the increase in the temperature around him. He finally stopped panicking when he caught a glimpse of red and orange on his arm. Turning himself to look upwards, he finally noticed the roaring inferno raging around him. Of course, this only caused him to scream even louder.
When he stopped for breath, he faintly heard the sound of screaming emanating from below him as well. Looking down again, he saw a city built into the side of the mountain, which he was rapidly descending towards. He slammed into the street at terminal velocity, but he didn't notice that he had landed in the middle of a group of technicolour equines, or that his landing had caused a huge explosion of fire, as he lost consciousness just before he impacted the ground.
Celestia descended on the scene of the calamity with mounting dread. Many pegasi were already bringing in rain clouds to try and quell the blaze, and were making slow but steady progress. Celestia herself assisted the firefighting effort by dousing whatever was on fire with streams of water she had conjured from her horn. Seeing the Princess herself assist the effort, the ponies already helping redoubled their efforts, motivated by her presence.
Celestia moved through the burned streets, coming across severely burned ponies in the process. Thankfully, she found no corpses, but the survivors had done so at a terrible cost. As she came across more and more of the injured, she called over several unicorns and instructed them to send up a flare when they came across somepony injured, and to pass the word along for others to do the same.
Soon, a worryingly large amount of flares was to be seen above the flames. Celestia observed them, frightened at the frequency of the flares, before they gradually slowed down, though one or two still were to be seen as the last of the injured were rounded up. Celestia headed for the centre of the devastated area, hoping to find what exactly the fireball had been. She heard a scream, and galloped toward where it had emanated from. Arriving, she saw a pegasus mare stricken down by the flames, staring ahead of her. Sending up a flare, Celestia looked to what the mare was staring at.
In the middle of the street was a large sphere of flame, slightly bigger than her. It did not appear to have a source of fuel, as it floated about a foot from the ground. As ponies arrived to retrieve the injured mare, Celestia began to approach the sphere. A few ponies made to follow her, but she waved them back.
"Do not come any closer, my little ponies. This could be dangerous." She warned them. Celestia continued to slowly approach, using a wing to shield her face from the intense heat. When she was less than two metres away, the sphere suddenly began to cool. Peeking out from behind her wing, she watched as it slowly decreased in intensity until she could look at it without shielding her eyes, and it lowered itself slowly to the ground. As it made contact, the flames dispersed suddenly in a wash of heat that forced her to throw up a shield spell to protect herself and once again hide behind her wings.. When she thought it safe, she looked at what the mysterious orb had deposited. On one knee before her, head looking down at the floor, appeared a bipedal creature. Slowly, it raised it's head to look at her, and she saw its eyes. Its sclera were a normal white, but its iris and pupil glowed an unearthly crimson. They remained like that, locked into each other's gazes for a mere few seconds, but to Celestia it felt like an eternity. Eventually, it's eyes rolled back into its head and it collapsed, unconscious.
Canterlot, Dungeons
Celestia looked into the cell where they had kept the being found at the scene of the incident, as it had not awoken since they had found it. Celestia could not make heads or tails of it. It appeared to be male, and it wore clothing, which indicated that it was civilised, and it had no fur except for a short mane on the top of its head, coloured ashen grey. An examination of its eyes showed that the hellish redness was gone, replaced by a more normal blue iris with a regular black pupil.
Most curious was that he had only appeared after the fireball had impacted Canterlot, suggesting he had either been inside it or summoned by it. She briefly entertained the notion that they were an extraterrestrial, as she had seen no such creature in Equestria before, and the blaze came from their craft. She quickly dismissed the idea as ludicrous however. His lack of injuries, be it burns or otherwise, also puzzled her. He had been at the centre of a great catastrophe but appeared to bear no ill effects from it.
He groaned, returning to consciousness, and she took a wary step back.
"Agh, my head..." He complained weakly. He sat upright and rubbed his eyes, looking around blearily. "Where am I?"
"You're in the Canterlot castle dungeons." Celestia replied. The being in the cell shot up at the mention of dungeons.
"Dungeons? Castle?... Canterlot?" He asked in confusion. Then his gaze fell upon her, eyes widening in shock. "Oh, my... Well, I guess we're not in Kansas anymore." He said sullenly.
"I don't know where this 'Kansas' is, but no, you're in Equestria. I am Princess Celestia, the ruler of this land along with my sister, Princess Luna." She said. "You appeared in my city amidst a great ball of flame that came from the sky."
"I... I did?" He said. "I don't remember much, only... I was falling. Falling from a great height. I..." He got up sharply and dashed to the bars of his cell. "Wait, you said flame? Was I on fire?" He seemed panicked.
"It would seem so. When you landed from the sky, a great ball of fire was around you. It caused much damage to my city, and many of my little ponies were injured."
He sat back down. "I guess it wasn't a dream or something then. Ah, fuck..." He leaned back and sighed.
"I know you are distressed right now, but I would like you to answer some questions for me: What are you, and how did you come to be in Equestria?"
"I'm a human, from earth. As for how I got here... I don't quite know myself. I can't remember much, but I know I was with my brother." He said. "Christ, I wonder if he's here too..." he added quietly.
Celestia observed him quietly. "I... do not believe that the flames were of your doing. I will allow your release, but I will be keeping you under surveillance." She stated, unlocking the cell door with her magic.
He rose to his feet and bowed. "Thank you, Princess." He exited the cell and stood beside her.
"Do you have a name, human?" She asked.
He nodded. "My name is Jason, Princess." Outside his cell, his possessions were laid out on a small table. He pocketed his cigarettes, lighter, and his keys automatically. Picking up his phone, he saw that it still had half a battery left of charge, but that there was no signal. He turned it off to save power.
Jason followed Celestia out of the dungeons. The path to the exit twisted and turned, with many side passages branching off of it. He realised that he could never have found his way out unassisted. The dungeons were probably designed like this to hinder anyone making an escape attempt, he realised. Eventually, they emerged into the interior of what he assumed to be Canterlot Castle. Upon his exiting the dungeons, a guard approached Celestia.
"Your highness, the creature! It is-" He began, but Celestia cut him off.
"I know, guardsman. I have allowed his release. I have judged that the conditions of his arrival were not of his doing." Jason waved sheepishly behind her. "Please have somepony send the necessary paperwork to my study." She said. "I will deal with it accordingly."
The guard nodded. "Of course, your highness." He said, before leaving.
"That was... incredibly easy." Jason said.
Celestia smiled at him. "Of course. They are but guards, and they follow my orders." Jason accepted this with a nod.
"Princess..." He began. "If it's okay, I'd like to see the ponies that were hurt from my arrival." She nodded at his request.
"Of course." She said, smiling.