Downward
A train screeched into Canterlot, its boilers glowing cherry red from prolonged operation at higher temperatures and pressures than they were designed for. The train itself wasn't any different from most that came in and out of Canterlot every day.
There were only two passenger cars attached to it, only two passengers on the train, and only two pieces of luggage on the train. There were no shipments of Crystal Empire goods, people or mail on this train. A cursory glance into the cabins would reveal that the train had been stripped of any extra weight outside what was necessary for the two passengers and its crew.
In short, this train was fitted to move fast from the Crystal Empire, day and night, without stopping. All other traffic on the rails was diverted out of its way well in advance as it screamed its way down the rails at a speed that was just this side of tipping it over.
One of the two passengers stepped out. The Princess of the Crystal Empire was not one accustomed to serious situations, even though Cadance often found them thrust upon her. Even then, she usually was able to keep a positive attitude, and seldom let her frown show through. Her frown was showing now. Even coded, the message from Celestia was terse, and tense. Celestia was not one to keep secrets unless she felt that the safety of Equestria was at stake.
The other passenger stepped out onto the platform. Shining Armor was used to having serious situations thrust upon him, as former captain of the guard and Prince of the Crystal Empire. Nevertheless, his nervousness showed through. Celestia's message said very little and spoke of problems within Equestria. The way things were going in Equestria, that hinted that his sister was involved somehow, or would be involved soon. Shining wouldn’t have been surprised if a similar letter wasn’t CC’d directly to Twilight word for word.
They were greeted on the platform by a squad of guards who checked the crown prince and princess over for anything, even going so far as to ask Cadance to remove her vestments of office. Several spells, some of which Shining recognized, some of which he didn't, were cast on them.
Shining turned to the head guard and huffed.
"And why was that necessary, Commander?"
The commander looked surprised, but then remembered the Crystal Empire wasn't even circulating Equestrian bits yet, much less Equestrian mail.
"Sir. I have orders to escort you to the dungeon. Celestia will be waiting for you there."
And that was all Shining could get out of them the entire trip into the palace, down through the cellars and into the Dungeons which were built into the crystal rock beneath Canterlot.
They came around a corner to find... Celestia.
But not the Celestia that Shining knew.
The Celestia that Shining knew could have been carved out of ice, but she was not cold to her fellow pony. The Celestia he knew could convince a rampaging dragon to halt with words alone, but seemed to have words enough for all who met her. She was never nervous, rarely agitated, and always, ALWAYS in control.
This was not the Celestia Shining had served under all his life. Signs of stress etched her face. Before she noticed their approach, she appeared to have been pacing back and forth. Her greeting to them spoke volumes of weariness, worry, and a hint of something that shook Shining Armor to the core--even more than when it looked like Sombra had won, even more than when Chrysalis had almost stolen everything from him. So much so, that he didn't even hear what she said, his mind was focused on one thing and one thing alone.
Celestia didn't know what to do, and she was afraid.
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Cadance couldn't find words, she hadn't seen Celestia like this either, ever.
"I suppose you're wondering why I asked you to be here now." Celestia said, her manner indicating she wanted to get around to the crux of the matter in the most roundabout way possible.
She paused, cleared her throat and started again.
"I'm sure you're aware of our victory over the changelings?"
Cadance finally woke up, half-remembering paperwork to that effect, among other paperwork, a mountain of paperwork. Her and Shining's responsibilities in a fledgling empire a thousand years out of date were great, and she could not remember much.
"I remember reading something to that effect. I couldn't look into it because we've been trying to get the Crystal Empire running again."
"Unfortunately, that is now a secondary matter."
Celestia took a deep breath.
"We believe that changelings have altered your sister's mind, Shining."
Years of military training cracked and Cadance noticed Shining's expression change, but he said nothing.
"Without her, we cannot use the Elements of Harmony and we are vulnerable to... Non-Conventional Threats." Celestia spoke the last as if it was a codeword.
"Are there likely to be any popping up anytime soon, Tia?" Cadance asked her aunt.
"While I hate to say it: Yes. Yes, there will be. Luna's return has altered power politics outside of Equestria, as well as inside. I don't have to tell you how many we've encountered in the last three years alone. Nightmare Moon, Sombra, Discord... Chrysalis."
"How sure are you that they've corrupted my sister, Celestia?" Shining asked.
Celestia sighed again. It wasn't any better when things slowed down. Doubts crept into her mind, festering. She didn't like being helpless, knowing that there was nothing she could do. Celestia could raise the sun, but she could not read minds, and she could not help Twilight escape from a prison that was inside her own mind.
She could only imagine what the real Twilight Sparkle was going through in there. Was she asleep? Unaware of the outside world going on around her as this... this fake operated her body for her? Or was she aware? Did she know every action, every shepherding impulse, while helpless to do anything about it?
Just as Celestia herself was helpless to aid her student now.
The thought that Twilight was honest, that she would ever side with the changeling queen, over her, was incompatible with Celestia's state of mind.
Celestia realized that Shining and Cadance were waiting for an answer.
"It is undoubtable she has been corrupted by the changeling, Shining. They spent a long time together. And her friends tell me they were close, too close, too quickly, even before whatever happened in the Badlands. She was on the changeling queen's side almost as soon as they met. Whether she knew or not. And then Twilight spent a long time out in the Badlands with her, alone."
"Surely that cannot be all, Princess." Shining said, in tones that said he expected a lot more evidence than that to accuse his sister of treason.
"You're not going to like this, Shining Armor. But your sister could not have escaped the Badlands without help. Skilled as she is with magic, there are far too many things out there that prey on magic users specifically. Her special talent would be a weakness out there. And then she admitted to helping the changeling queen out, and putting that magic limiter on her horn. I can only assume she is now an agent of the changelings in the Badlands… and wholly under their control."
Cadance took it well, at least outwardly. Better than Shining did.
"Can we see her." What Shining meant was: I want to see her for myself. His voice was flat.
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Twilight's cell was different than Naudia's. She didn't know it but she was treated a lot better than her girlfriend. The toilet was something that the average pony on the street would recognize, and even use. It looked newly installed. So did a lot of the furnishings around the cell. The bed had no lumps in it. The window, while magically sealed and barred, provided a (magically generated) scenic view to the outside world. The food was well above average, compared to typical prison food, something a pony off the street might actually have paid for.
Twilight Sparkle noticed none of this. She could see none of it through the fog of depression.
Twilight Sparkle never realized it, but she was very rarely, if ever, alone in her entire life. Even at school, she made friends with her teachers, and she was never more than 100 feet away from another pony who at least wouldn't stand up if she decided to sit at their lunch table. Even in the Badlands, she had Naudia.
The Badlands...
Naudia...
It hurt to think about her. Everything about her revealed new avenues for hurt to assault Twilight. The history of the changelings was all one long slow decline, like a festering wound infected with prejudice and fear. The current status of the changelings still alive was a puzzle of impossibilities revolving around food, breeding, and land.
And Twilight was at the center of it all. Broken. Broken and in prison, abandoned by her friends, abandoned by Celestia. Her mood spiraled downward, feeding off of itself.
She felt responsible for the actions of her ancestors. She felt responsible for the deaths of all the changelings in Canterlot. She felt responsible for failing Naudia.
The door to her cell opened.
Twilight did not look up, she did not care who it was. They would not listen to her, no matter what she said.
"I don't know why you bother to come back here." Twilight said to the clink of metal horseshoes. "You will never hear anything I say."
Twilight wasn't chained down, but that didn't matter to her. A magic suppressor locked away her magic. Her special talent. It wasn't often that a pony hated their special talent, but in this gout of depression and helplessness, it was just another thing for Twilight Sparkle to be depressed about.
Twilight learned not to listen when anypony came into the room, because she knew everything Celestia would have to say. It had all been said a hundred times. Things like:
"Don't worry, Twilight. If you're still in there, I will find a way to get you out."
"Come back to me, Twilight, please!" Celestia had even sounded like she meant it too. "Come back..."
"This is for your own good, Twilight."
And other such phrases that tore at Twilight like no insult, no sword ever could.
She was brought back somewhat to the real world when she noticed that the alicorn trying to talk to her was pink, not white.
Slowly, not daring to hope lest her foalsitter disappear in a puff of imaginary smoke, Twilight looked up into her face.
"Cadance?" Twilight asked.
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Cadance looked at the unresponsive form of Twilight, lying on a bed clearly moved in from another part of the castle, sitting in the most worrying room Cadance had ever seen.
The cell was one quite small step away from a padded room. There was nothing sharp in it, not even anything that could possibly be made sharp. No edges on any of the sparse furniture. Even the toilet was gravity-fed without water. There was a sink, but it could not hold water. All this, and a number of other telltales about the room, revealed that the changes were not to prevent harm to the guards.
But to Twilight.
The room sent chills down Cadance's spine. That Twilight needed to be housed in it only sent an even deeper shiver, rooted somewhere in a shared childhood.
"I don't know why you bother to come back here." Twilight said darkly not looking up from the wall. "You will never hear anything I say."
"Twilight? It's me... Cadance." Cadance said.
Twilight said nothing, didn't even acknowledge her existence.
Coming around to Twilight's line of sight finally got a reaction out of Twilight. She turned slowly to look at Cadance with a look of disbelief on her face.
And then Twilight hugged Cadance like she was the last pony on earth.
Twilight said nothing for a long time.
"You have to help me, Cadance! I've... I've never felt so alone before." Twilight whimpered so quietly that Cadance almost didn't hear her.