For the first time in a month, the sound of running hooves echoed across the valley as seven ponies ran down the dirt road. Nature took notice; birds looked down from their nests, bunnies poked out of their holes, and squirrels turned from their nut gathering to see them as the six mares chased after the blue-coated colt.
"Coshtarnit, Doctor!" Applejack yelled. "Can't ya slow down for one apple-pickin' second?"
Twilight didn't know what to make of the Doctor. Just this morning, he had been stumbling over his own hooves in the middle of the forest; now he had become a rambling colt who they were struggling to keep up with.
The Doctor finally slowed when the edge of the forest came into view. He led them farther in, stopping in the clearing where Twilight had first met him with the blue box.
"Right where I left her," he said, fumbling in his pocket.
Rainbow Dash wasn't impressed. "So, you led us running all the way out here, leaving all those ponies behind, just to show us a tiny blue shed?" Seriously, what kind of pony are you?"
"Well, technically," said the Doctor, "I'm not a pony. I'm a Time Lord, from Gallifrey. And this is not a shed, it's a –"
"Alright, that's it!" Twilight stomped her hooves. "I can take finding you in the middle of nowhere, stumbling over your own hooves, and your babbling about Celestia-knows-what, but now you claim you're not even a pony? Has anypony ever told you that you're crazy?"
"Once or twice," the Doctor admitted, pulling out a key and inserting it into the box's lock. "Well, more like ten times. Well, more like every person I've ever met. But you're the first pony, so good job on that."
Twilight slapped her forehead and groaned. "Oh, this is too much!"
"Alright, it's your choice if you don't believe me," the colt said, shrugging. "I'll just step inside my 'shed' then and leave you on your merry little way." He opened the door just wide enough to fit through and slipped in.
"Oh, no you don't!" Twilight yelled, following the colt into the box. "You're coming out and telling us who you…really…are…"
The box's interior was enough to silence any further accusations the mares held. It was impossibly large, rising higher than the trees outside and wider than their trunks. The walls were painted gold and dotted with white octagonal lights. In the center, a clear pillar rose, its base surrounded by a console covered with all kinds of instruments.
The Doctor leaned against the console, crossing his front legs with a confident grin. "So…what do you think?"
The mares simply gaped at the room until Pinkie Pie jumped up excited and shouted, "Oh! Oh! I know! It's bigger on the inside!"
The Doctor smiled even wider. "Even ponies say it. I love it!" He jumped up and beckoned them forward. "Go on, take a look around. Just be careful, and whatever you do, don't –"
"WOAH!" Rainbow Dash yelled from down the hallway. "There's even more stuff over here!"
Any control the Doctor had over the group was instantly lost as they ran through the halls, discovering what other wonders were in store.
"Oh, my!" Rarity gasped. "What a magnificent wardrobe! Such exotic designs and – what? Bowties? Ugh! How dreadful. That simply will not do."
Applejack sniffed as a familiar scent caught her attention. "That smell…it can't be…an apple orchard! I don't believe it! There's sunlight an' ev'rything in here!"
"Aw, cool! He's got a pool in here!" Rainbow Dash said excitedly. "It's even got waterslides! This is so awesome!"
"Oh my gosh!" Twilight gasped. "This library is gigantic! All these books…I couldn't read all these in a hundred years!"
Pinkie Pie hopped from room to room, her attention continually stolen from one place by the next. "Oh, what's this? Hey, that looks cool! Ooh, shiny! I could have the biggest party EVER in here!"
The Doctor noticed that Fluttershy hadn't left the control room; rather, she seemed awestruck, perhaps a bit afraid, of the chamber's enormity.
"Like it?" the Doctor asked, wrapping his hoof around her shoulders as the other five ponies returned. "I call her the TARDIS – that's Time and Relative Dimensions in Space. I've travelled all around the universe in this girl. As you have seen, there are all kinds of rooms here, but this," he extended his other hoof and waved it in front of the console, "this is where the magic happens."
Pinkie Pie reached for a lever. "Oooh! What's this do?"
"DON'T!" the Doctor yelled, diving across the room to protect the lever in question from the hyperactive pony. "That," he said slowly, "is the Wibbly Lever. I'm not quite sure what it does yet, but there's a slight chance it could tear a hole in time and space roughly the size of Belgium if not used correctly." He eyed the six mares. "So please, unless I ask, don't. Touch. Anything. Got that?"
The six mares all nodded in fear. After a few seconds of silence, the Doctor smiled and rubbed his hooves together. "Right-o! Twilight, I'm going to need you for some tests. Now, don't give me that look, this won't hurt a bit…"
*~*
A few more-or-less painful minutes later, Twilight Sparkle stood covered from head to hoof with wires, instruments, and other strange objects she couldn't identify, all culminating with a metal dome that sat uncomfortably on her head. The wires led to the TARDIS' console, where the Doctor busily pressed buttons and turned knobs (with some difficulty, thanks to his new anatomy). The other five mares had taken seats around the room, having become bored of the Doctor's project some time ago.
"I swear, I am never going to participate in any of your ideas ever again, Doctor," Twilight said bitterly. "If this doesn't kill me first."
"Oh, don't be like that," the Doctor said, while trying to figure out how on Gallifrey he was going to use the keyboard with hooves. "Think of this as a science experiment. Imagine: 'The Doctor and Twilight Sparkle: Discovering the Mysteries of the Ponyville Plague.' Hmm, 'Ponyville Plague,' I like that. Could somebody write that down?"
"What exactly is this theory of yours, Doctor?" Rarity asked.
"Hold on…" the colt tried to type, but soon threw up his hooves in frustration. He then pulled out his sonic screwdriver and, holding it between his teeth, used it to tap out a command.
"There we go!" he said as he finished. "Anyway, Rarity, it's not really a disease, strictly speaking; it's more of a series of symptoms caused by outside manipulation by a foreign entity."
"Smaller words, Doc," Dash said boredly.
The Doctor sighed. "Aliens are doing stuff."
Wires rattled against each other as Twilight moved towards him. "Okay, I'll admit I was wrong about this whole TARDIS thing, but…aliens? Really?"
"Of course, Twilight. I'm an alien, after all. Time Lord, remember?"
Twilight looked up and down at him in amazement. "But…you look pony."
"You look Time Lord," the Doctor countered, then looked up thoughtfully. "Actually, you don't; I do look pony right now, so I guess that makes me a Time Pony. Did we even have ponies on Gallifrey? Because, if we did, and they shared certain biological features with us, then technically they'd be Time Ponies, unless of course –"
"Doctor!" Applejack yelled.
"What? Oh, yes! Sorry!" He went back the main computer. "Where was I? Oh, yes – aliens are doing stuff."
"Alright," said Twilight, "assuming there are 'aliens doing stuff,' how do you know? You just wave your little blue flashlight and that proves it?"
"First of all, it's a sonic screwdriver. Second, yes, that's part of it."
"And the other part?"
The Doctor rotated the screen around for her to see. "There's one in you right now."
The six mares gasped as they saw the readings. Inside an outline of Twilight's body, a dark, amorphous blob writhed around. An unearthly noise, something between a hawk's screech and a bear's roar, emanated from the creature. As it moved, strange tendrils stretched towards Twilight's head and latched on to her skull.
"And it's not just her," the Doctor said in a serious tone, "there's one inside all of you, and everyone in Ponyville. That thing is a species of empathivore. The more common variety, the mörkön, has a physical form, but this one here is entirely composed of psychic energy."
Twilight slowly shook her head, eyes wide with fear. "No…it can't – that's impossible!"
"Anything's possible," the Doctor replied. "Little guys like that are wiggling inside your brains as we speak. As psychic energy, an empathivore can jump into a person's mind and generate a small field of despair, around itself, causing their host to feel negative emotions more readily. It then feeds off that energy, and uses it to grow and multiply, while the host slowly dies. After that, it's a simple matter of finding a new body to begin anew.
"What's curious about yours, though," he continued, leaning against the railing, "is that yours are entirely docile. No psychic leeching, no despair field, nothing. They're just…there."
"So how do we find out why?" Twilight asked.
"Research!" The Doctor jumped up and walked to the door. "We'll just pop back into Ponyville, do a few more tests on the sick ponies, and – oh."
The mares joined him and looked out the door to see every pony from Ponyville standing outside the TARDIS, all with no signs of sickness.
And with blood red eyes.
"Backinbackinbackin!" The Doctor pushed the mares backward and closed the doors just as the first ponies slammed into the TARDIS.
"What the heck was that?" Rainbow Dash demanded. "They were all bedridden when we left!"
"The empathivores can take over their host's bodies when threatened," the Doctor replied, running to the center console. "It's how they keep people from stopping them if they are found out!"
Dash rolled her eyes. "Well, that would have been nice to know a few hours ago. We could've locked them inside town hall!"
"I didn't think they had enough energy yet!" The colt ran around the circular panel, pushing and pulling on a seemingly random sequence of buttons, knobs, and what appeared to be a bike pump. "Besides, I don't think a wooden door would have stopped them."
"But that door's wood!"
"No, it just looks like it!" As he pulled a final lever, the glass orb in the center column began to move and the whole room started to shake.
"What's happening?" Rarity asked.
"I'm starting up the TARDIS," the Doctor replied. "It's time we got to the bottom of this. Strap yourselves in, girls; we're going to Canterlot!"