Twilight waved her cybernetic leg over her head, to try and get this new survivor's attention. Then she realized this would probably scare whoever-it-was away, and waved her natural foreleg over her head instead. "It's Twilight Sparkle and Rarity!" she shouted. "Come on out!"
A wee unicorn foal, once as white as snow but now a mottled amalgam of grey fur and greyer metal, scampered out toward them. Her rump, too, was exposed, but there was no cutie mark to be seen.
"Sweetie Belle?" Twilight called out as she approached. "Is that you?"
"Twilight! Rarity!" the little one said as she reached them. "I'm so scared! Where did everypony go? Where are we?!"
"We're in Ponyville," Twilight said, "Or what's left of it. I think the rest of the ponies are ..." She looked into Sweetie Belle's big, terrified eyes and nearly broke down crying as another piece of this new reality hit home. "... are part of the Borg now, on that giant cube. I wish I had better news."
"No!" Sweetie Bell half-whispered. "Scootaloo? Apple Bloom? They're gone? But we're the Cutie Mark Crusaders! We ... we can't ..." Her breathing came in rapid gasps. Her gaze darted from side to side, looking desperately for some way out of this terrible news, for some hope that it might not be true. "No, no, no!" She shook her head violently, flinging tears. Then she buried her face in the metal-plated shoulders of Rarity, her sister, and sobbed.
Rarity put her foreleg around her younger sister, and felt the tears well up in her own eyes. Twilight closed in and hugged them both; her one remaining eye was getting blurry too.
A shadow passed over all three of them. Twilight cringed. Oh no, not the Borg cube again! Twilight glared back up at the sun ... but instead of a square shadow, she saw the shadow of a mare with outstretched, feathery wings. It was the most beautiful, most welcome sight she'd seen all day. "Princess Celestia!"
The white mare fluttered her magnificent wings as she braked for a graceful touchdown. Not a single speck of Borg circuitry besmirched her regal form. The sun filtered through her translucent, flowing mane, casting glorious rainbows for yards around. "Twilight Sparkle!" she said, as glad to see her protegé as Twilight was to see her. "You escaped too! I can't tell you how much my heart lifted when I recognized your cutie mark from the sky."
"Princess, I'm so sorry!" Twilight said, and pointed to Rarity and Sweetie Belle. "These were the only two survivors I could find."
Celestia looked down at her favorite student with a bittersweet grin. "This is actually better than I'd feared. I wasn't sure anypony would be left in Ponyville. Twilight, Rarity, Sweetie Belle: You need to know that this disaster wasn't localized. These 'Borg' have abducted ponies from all over Equestria. Canterlot is practically deserted. I escaped because the moment I appeared aboard that metal cube, I dug into my memory and cast a long-range teleport spell that I'd mastered some years back. The good news is, so did my sister Luna. We're both untouched. And I've met several unicorns like yourselves who survived the ordeal with ..." Her face twisted into a scowl. "With modifications to their bodies just like yours." Her eyes grew more desperate, almost pleading despite her regal bearing. "But I have not seen one single earth pony or pegasus pony anywhere on Equestria. Luna's gone off to search Cloudsdale for pegasus survivors, but I'm afraid we have to assume the worst."
Twilight looked up into her Princess's eyes with the one eye she had left. "I might be able to find out where some of them are."
Celestia puzzled. "How? Is there a spell you've discovered in your studies?"
"No," Twilight replied. "The Borg made one big mistake with me. They implanted this transceiver" — she tapped the right side of her head — "Before they tried to cut off my horn. I have access to all their comm traffic, and every scrap of their knowledge base." Her eye rolled up into her head and her brow furrowed as she scanned the collective. "It's hard to look for individuals. Borg don't identify each other by name. Gotta look for drones of species 14864 ... there's one. It's an earth pony, I'm pretty sure. ... Oh heavens. It's Applejack."
"Applejack?" Rarity asked. "She's alive?"
Twilight was grim. "I wouldn't exactly call it 'alive.' She's slaved in to the collective. She's a drone, carrying out the will of the Borg. The real Applejack is buried so deep under that command network that she can't get out no matter how hard she tries. Wait ... there are others ... yeah. Yeah. That drone's Pinkie Pie. ... I think that one's Fluttershy, but I can't see its cutie mark to be sure ... Damn. There are so, so many of them."
"Can you tell where in this 'collective' they are?" Celestia asked. "I mean, where they're physically located?"
"They're leaving the solar system," Twilight told her, "Headed for interstellar space."
Celestia puzzled. "What do you mean? Headed for one of the stars that appears at night? What would they want with a simple point of light in the sky?"
Twilight stared at her mentor in disbelief. "You mean, you don't know? Your highness — Celestia, the stars are distant suns."
Both Celestia and Rarity looked at her incredulously. "You can't be serious, my dear," Celestia said. "The sun is so much brighter!"
"The stars are so far away they appear much dimmer," Twilight explained. "Like how a candle flame looks dimmer if you see it from a mile away than if you see it right in front of your face. The stars are fantastically far away. So far their light takes years to reach us."
"Amazing," Celestia said. "I wonder if any of those distant suns has its own Equestria, and its own Princess Celestia to make its sun rise in the morning! Oh, but that's ridiculous. If any of those stars rose and set over their own world, we would see the star wiggling around in a little circle!"
"Um ..." Twilight scratched the back of her neck with her hoof. Another uncomfortable topic. "That's something I've been meaning to talk to you about. Have you read the works of Nicholas Coponicus?"
Celestia shook her head in bewilderment. "Should I have?"
"It is kind of important to your whole ... sun-raising task. You see, the sun is actually a hundred times bigger across than Equestria. It's millions of miles away. When you make the sun rise in the morning, you aren't actually moving the sun, you're moving Equestria."
"Oh, come on," Celestia glowered down at her.
"I'm not kidding," Twilight continued. "The sun appears to rise, and move across the sky, and set in the evening, because Equestria is rotating on its axis."
Now Celestia looked even more confused. As did Rarity.
"Princess," Twilight said flatly. "Equestria. Is. Round."
Celestia and Rarity looked at each other, then both broke out laughing. "Oh, Twilight!" Celestia said between chuckles. "You really had me going there for a moment! Round! Ha ha! If Equestria were round, you'd fall off unless you stood right at the top dead-center of it."
"Ugh," Twilight groaned. "I see you haven't read the works of Sir Isteed Newton either. Equestria is thousands of miles across. Its mass is what creates our gravity. 'Down' isn't some absolute direction in space, it points toward the center of Equestria from any point on its suface! The ponies standing on the opposite side of Equestria are pulled 'down' in the same direction we call 'up'."
Sweeite Belle blinked, then crossed her eyes in befuddlement.
"Or at least they were," Twilight corrected herself, "Before the Borg abducted them."
Celestia sighed. "This fantastic picture of the universe you've painted is a lot for anypony to take in all at once, even a princess. I'll have to verify it with my own scholars — many of whom are probably aboard that Borg cube right now. So tell me, in this vast universe, do you know how the Borg fit into the big picture?"
"I'm not sure yet," Twilight said, "But I'm learning more about them every minute. Hmmm ..." She focused on the collective again. "I can find no indication that they use magic in any way, shape, or form. But their technology base is incredible. Artificial gravity, microscale electric circuits, teleportation, force barrier projection, attractor beams, faster-than-light travel ... Ugh. It looks like they go from one inhabited planet to the next, abducting its inhabitants and 'assimilating' them into their collective, in some sick never-ending quest for 'perfection.' Then they harvest as much of the native construction as they can for raw materials, and move on. So why did they stop at Ponyville? Why didn't they dig up Canterlot as well? ..." She searched the voices in her mind, then gasped. "They're afraid of us!"
"Afraid of us?!" Rarity asked.
Twilight nodded, still searching, still listening in. "It's our magic. The Borg like an ordered universe, where every action has an utterly predictable reaction. When an enemy uses a new weapon against them, they learn how it works and adapt. But magic is chaotic. It works a little differently every time. They can't adapt. They have no defense whatsoever against unicorn magic. They discovered that the hard way, when they tried to cut our horns off."
"Hmmm." The wheels in Celestia's head began turning. "I wonder if it would be possible to combine our magic and free the ponies they've captured."
"That's what I was just thinking," Twilight said, "But they're already two hundred million miles away. The farthest I've heard any spell could reach was half way around Equestria. Unless you know of a longer-range spell —"
"I don't," Celestia said, and hung her head down. "I've never looked for one. I didn't think the universe was big enough to need a longer-range spell."
"Then we'd have to catch up with them. And there, I don't think our magic can help us. We can make wings to fly in the air, but no spell will let a pony fly into space, let alone outrun a light beam. How the heck can we catch up with ..." Twilight blinked her one remaining eye. "How far?" she whispered to herself. "How to ... how to ..."
Sweetie Belle tugged at Twilight's tail. "Are you havin' a nervous breakdown?"
Twilight didn't flinch. It was as if she didn't notice the world around her at all. Seconds ticked by, and she seemed as rigid as the metal plating her flanks. Then, with a low intensity, she whispered: "Improvised."
Rarity and Sweetie Belle were backing away, slowly, when suddenly Twilight snapped back to life. "We can do it!" she announced. "They're only moving away at warp factor one to save fuel. I found a whole reference library of improvised Borg technology; instructions in case some of their drones get stranded on a lifeless planet, so they can build what they need to survive and get back into space. We can build these gadgets too. All I need is a way to disseminate the instructions to the surviving unicorns, and we can theoretically build anything the Borg can."
"The Borg sound like monsters," Celestia said. "Is their technology safe?"
"Maybe," Twilight said. "Maybe not. But I don't see any other choice. Once the Borg cube reaches the inner comet cloud, they're planning to kick their speed up to warp nine, maybe higher. If we're going to have any chance of saving our friends, we're going to have to build a complete, functioning starship of our own in under a week."