"Last stop: the Crystal Empire!"
The lights on the train were dark, making it hard to see Starlight's eyes as the announcement interrupted her story. A faint chill pierced the insulated train car, the kind Twilight Sparkle was only aware of because she knew it was frozen outside, though if she hadn't it would have gnawed at her like a background noise you could only hear once it stopped. The sun hadn't yet risen. They were the only passengers in that car.
"We should return to the castle," Cadance said, breaking a silence even Rainbow Dash had known better than to tamper with. Like that, Starlight's spell was broken, and Twilight found she had a voice again, though she didn't know what to say.
Steam hissed from the train as Twilight disembarked, following close behind her student. Rainbow flew ahead, dawn tinging the eastern horizon with a light that didn't seem to touch the ground.
"You know," Twilight said, "you were enjoying telling this a lot more at the beginning."
Starlight's mane didn't perk. "They were my friends for a reason. There were a lot of good memories I hadn't looked back on in a while."
"But now your voice is so sad." Twilight kept her horn dim, respectful of the darkness, but it didn't stop her from looking intently. "And I can't see your eyes, but I can only imagine how they must look. Starlight..." She took a breath. "You need to stop telling this story. It's not making you feel good, and at this point I don't even want to know whether I'm right about the ending."
"No," Starlight replied. "With all due respect, I can't. This is the first time I've ever been able to say some of these things, and they need to be said because you need to understand who I was and why I did what I did with your map table and what you did to me in my village. And I want to have someone who understands. When I'm done, we can go back to Ponyville and drink hot chocolate and make snow angels, and we can laugh about our plans for the future. But I need to finish this first."
Twilight opened her mouth, but found no words would come. Eventually, she swallowed. "It's my job to tell you that talking about your feelings is the first step in coming to terms with them, no matter how much it hurts. But you already know that."
"But you're telling me otherwise," Starlight said, "because friendship is magic and you're the princess of that and you don't want it to be true that it just wasn't magic enough for someone who believed as hard as I did to keep their friends."
Twilight frowned. "I'm telling you because it looks like talking is making you miserable and you've clearly had enough of that for one life. But yes. That too." She sighed. "I am a princess. This is the kind of thing that it should be my duty to fix, and I can't see anything I can do."
Starlight continued her walk. "Listening? Existing? Offering to be my friend?"
"Right." Twilight's ears fell. "I know how important that is, but everything I'm doing just feels like treating symptoms instead of the real problem."
Starlight shook her head. "Much as I'd like to blame everything wrong in my life on some curse or malicious power or cause beyond my understanding I could somehow defeat with friendship or someday be rid of, that's missing the point. This happened to me years ago, and there's nothing I can do to change it except live with the results. There are some problems you can't fix."
"Says the mare who invented a time travel spell using work from Star Swirl the Bearded."
Starlight continued walking.
"Starlight!" Twilight ran to catch up, the road shadowed by pools of light from ponies who had left their porch lights on. "This isn't something you should have to live with!"
"No," Starlight agreed, "it's not. But whether I should or shouldn't, I do. And whether I do or don't, I can. And you and your friends actually have a magical power binding you together, and if I stay with you it will be a lot more livable than how I've been surviving for the last decade and a half."
"But it's not right!" Twilight protested. "I should be doing something, or..."
"Are you actually going to do it?" Starlight asked, staring straight ahead. "I should be too, but that's not enough of a reason to do it."
Twilight's face fell, and her pace slowed. "I hate that you asked that."
"Then you're probably right about what happened to my friendships."
That was all Twilight could bring herself to say. The sun rose as she and Starlight walked in silence, rising high enough to cover the city in long shadows from the crystalline houses, its light not touching Twilight's coat. Early-rising ponies were starting to wake, and a few glittering hooves waved at her from kitchen windows. It didn't make her feel surrounded. There was only one mare and two groups of friends on her mind, and one of those groups was her own.
"This crystal is the same type as the crystal palaces," Starlight said as they approached the base of the tower, a spinning, heart-shaped gem visible at the center of the plaza.
"It's similar in structure to my tree," Twilight answered, not interested in small talk but feeling like it was better than silence. "I've studied it a time or two."
Starlight stepped up to the crystal heart and regarded it, her mane still limp. It hung in midair between two spikes of crystal, one from the ceiling and one from the ground, and as it spun the air seemed to shimmer with power, flowing around Twilight like a large, gentle wing.
"I don't know how much you'd know about this place," Twilight offered, "but the crystal heart is an artifact that contains and acts as a focus for the crystal ponies' love. Keeping it here supposedly lets it spread its love all across... Starlight?"
Starlight was more interested in the spikes the heart hung between, poking at the bottom one with a hoof. Twilight quizzically tilted her head, mouth half open.
"If you've ever wanted to see Indus technology in person..." Starlight lit her horn, and suddenly the bottom spire vanished like a hologram, revealing a spinning drill-like device that had been encased inside it. "That's a harmony extractor."
Twilight gaped. "How did you know that was there!?"
"The shape was right." Starlight shrugged. "And it makes sense with what you said this was used for. There's one in the top, too, I'm sure."
The sharp, conical extractor spun soundlessly, teal energy dancing along its surface. After a few seconds, Starlight's horn went out, and the crystal covering re-materialized, leaving it looking exactly the way it had been before.
Twilight took a deep breath. "Starlight," she said. "Tell me you can know that there are mysteries like that in the world and not feel like there should be a way for you to fix everything that happened to you?"
"Who gets to decide what there should and shouldn't be, Twilight?" Starlight turned her back on her again, the sunlight starting to touch the ground. "I need to finish. We're almost to the end, and once the story is over you can speak to your heart's content about regret and what should be possible."
"We get to decide!" Twilight's ears rose in indignation. "If there's something that isn't right, we can tell! That's part of being a pony! Even the ponies I've met who were in the wrong or needed to be stopped all had real grievances about things that were wrong with their lives!"
"And what about when you're terrified of making that decision?" Starlight whispered. "What about when you've been told day and night by visions and a filly you don't understand that you will decide something needs to happen someday but you're wrong, and everything suffers as a result? What about when you're a foal whose talent seems to be doing anything, and you know no one could stand up to you if you did? What about when some magical glass shows you that the memory that impacted you most was a memory of watching a vision of what you might do, and catapults it from a lingering fear to the first and only thing you can think about?"
"I stood up to you," Twilight said, a dawn breeze blowing through her mane.
"You didn't stand a chance," Starlight countered, countered, her voice tight. "Even as an alicorn, you had to talk me down."
"But I did, didn't I?" Twilight stepped forward. "And it worked. Because that's what friends do. They talk to each other and tell each other when they're wrong, and they respect each other enough to listen. Maybe you can beat me in a magic fight, but that has nothing to do with it as long as you care enough to listen. Your friends don't have to be stronger than you to be able to protect you from your own bad decisions, no matter how much harm you could cause by making them."
Starlight broke down and crouched, covering her head and crying.
"Shhh," Twilight whispered, touching a wing to her shoulder. "We're taking a break and getting some sleep before we finish. And then if going back to Ponyville and living a normal life is what you need? I'm royalty, and I manage to pull it off sometimes. I'm practically an expert."
She gave an awkward, reassuring smile, and Starlight hiccupped. "I w-was terrified of myself. The seeds were there all along, being sown every step of the way. And then they all sprouted all at once, and I realized I really could cause something like that, because I was strong enough and a-all it would take was choosing the wrong thing to make my goal. Cutie marks are goals, and also the power to help you reach them. I t-thought that without those..."
"It's okay," Twilight consoled, her eyes finding their way to the mark on Starlight's flanks. "I understand."