Sunset squinted ahead into the wind as Luna's wings sliced through the bitterly cold air. Her horn glowed faintly, keeping her attached to the alicorn's back. The orange glow from the horizon was rising over the peaks ahead, growing bright enough to light the snow beneath them.
"Princess?" asked Sunset.
"Hmm?" replied Luna.
"I know you said it's not the sun… but what is it? It's getting too bright for me to look directly at it."
"It's Celestia," replied Luna, who was staring directly into the light without squinting. "She is channeling enough magic that she is giving off the glow you see. It's looping to the earth. I've been trying to discern why."
Sunset squinted forward, but she could not look towards the intense orange light without it hurting her eyes. "How can you look at that?" she asked. Luna merely grunted in reply.
After a moment Luna started to bank and then descended in a long, sweeping spiral. "We should pause here," she commented. "It would be dangerous for us to get too much closer without understanding what she is trying to do."
They touched down about a half mile away from the glow, and Sunset hopped off Luna's back as the alicorn lighted atop the snow. As Sunset's hooves pushed through the icy crust she yelped. "It's deep here," she complained. "The snow is nearly up to my chest!"
Luna seemed uninterested in the complaint. "Do you feel it, Sunset Shimmer?"
"Huh?" Sunset paused for a moment to let her senses focus on something other than the icy snow surrounding her legs. After a moment, she did. "The ground!"
Luna nodded. "Yes. She is feeding all that power into the ground. I do not think it would be wise to send you ahead."
"But why?" mused Sunset Shimmer. "Directed magic like that, it's like she's trying to break something…? What is going on?"
"She draws from the land, too…" mused Luna, suddenly sounding distracted. Her eyes focused, however, as she watched the distant scene intensely. "She's wobbling…" Luna added with sudden concern.
Sunset turned back towards Celestia, squinting her eyes as she tried to see into the light. "What?" she asked, her own concern leaking through. Before she could get her hoof up to block the light there was a sudden flash, followed quickly by a loud bang. Sunset's eyes slammed shut against the light and she heard a gasp from Luna followed by a massive rush of wind and feathers.
Sunset opened her eyes to find the area much darker than it had been a moment earlier, and she cast her gaze northward to see an orange ember falling from the sky, only to vanish as it hit the snow.
"Princess!" she cried. She looked around and saw that Luna had already taken to the sky and was rushing towards the fallen ember. Sunset tried to run, but the deep snow made it impossible. After a few hopping steps she lit her horn and considered.
"I can't wink… it's too far and I've never seen that site anyway. I could levitate over the snow, but probably not that far. Maybe…"
She concentrated for a moment, and large glowing snowshoes appeared at the ends of her hooves. She was able to stand atop the snow with them and after spending a moment to gain her balance, she started off at a quick trot.
"She must have overloaded…! I've never read anything about what you're supposed to do."
She glanced up at the sky. It was difficult to make out Princess Luna against the dark sky, but she could see that Luna was well ahead of her and would probably reach the site in seconds. She looked ahead again and estimated it was going to take herself another four to five minutes at her current rate. She wracked her brain as she considered the medical guides she had studied during her exile from magical training.
"It's often described as burning out… would literal burn aid help? She had too much power… would it be the same as a magical myorrhexis? Hyperkinesia…?"
She at last began to draw near and saw that Luna had already landed and was facing Sunset's approach, crouching on the other side of Celestia. Luna had lifted Celestia's head from the snow and was supporting her neck carefully, and was softly calling to her. Sunset trotted up cautiously, releasing the snowshoe spell as she found the snow here largely blown away and the rock laid bare.
"Is she okay?" whispered Sunset as she drew closer.
Luna looked to her, and then motioned Sunset closer. "She is unconscious, but she is alive. Come here and help me to support her neck."
Sunset stepped closer. Her heart caught in her throat as she saw Celestia laying limply against Luna. Her eyes were closed and her mane had reverted to the simple pink that Sunset remembered from when they had first reunited. The tip of much of her fur was singed, giving her a darker color than she normally sported. Sunset lit her horn.
"No magic!" snapped Luna. She continued more gently. "She has overloaded and her reserves have drained. We need to let her recover naturally to prevent further injury. She should be fine if we can allow her to rest."
Sunset released her spell before it was completed and nodded. "Oh," she responded softly. She put her hooves under Celestia's neck and supported her gently, making an uncomfortable face at seeing her mentor so helpless. "Sorry. I was trying to decide whether traditional treatments might be helpful?"
Luna shook her head. "It is unlikely," she responded. She frowned and looked down into Celestia's face. "Oh sister," she said softly. "None of this is how I envisioned our reunion would be…"
Sunset frowned softly and looked up to Luna. "You wanted her to come back? I thought you wanted the night to last forever."
Luna made an uncomfortable face and then looked back to Celestia. "I was afraid of the battle that her return would signify. But I never wanted to see her like this." She paused for an uncomfortable moment, then added more softly, "Sister, what were you trying to do?"
Something caught Sunset's eye behind Luna. She craned her neck to see, careful not to move Celestia, and her eyes grew wide.
"Princess… do you remember the story about the Crystal Empire? What if she was searching for that?"
Luna shook her head slowly. "The Crystal Empire was lost… it was beyond our magic. It has been lost for a millennium."
Sunset's eyes didn't waver. "What if she had all your power and all the power of a cursed amulet?"
Luna responded slowly, looking to Sunset as she spoke. "Even with all that, the likelihood of success…"
Sunset pointed slowly with her free hoof, interrupting Luna. "…Because I think she found it."
Luna frowned and turned her head back to follow Sunset's hoof. Her eyes widened and her jaw dropped. "By the stars…!"
Behind Luna, slowly fading into view, was a massive city of gleaming crystals. Though she had never seen it before, Sunset had no doubt in her mind that this was the city Celestia had mentioned. Celestia had managed to break the curse and restore the Empire.
-----
Sterling was not certain how much time had elapsed when he came to again, but the world was still dark. He could tell by the stillness of the air that he was indoors, but he did not move and he kept his eyes mostly closed to avoid betraying signs of consciousness. His ears moved subtly as he listened carefully for any movement around him. Finally, hearing nothing, he slowly pushed himself to a standing position.
Still cautious, he held his position. He waited to see if anypony else might move now that he was standing, while simultaneously taking stock of his situation. He was both surprised and relieved to see that he had all his equipment and that his armor was intact.
"Well, if I was a prisoner then they would at least have taken my sabre," he considered.
Finally, he dared to light his horn, casting light around himself to inspect his situation. The floor beneath his hooves was stone, as were the walls around him. He was in a large round room of at least thirty feet diameter. There was only a single door, but a large spiral staircase went upwards and out of sight along the wall.
Cautiously he approached the door and then listened against it. It was completely silent behind it, so he turned his attention upwards. The stairs continued on into the shadows above him, offering no clues as to how far up the ceiling was.
"What did that wolf do to me?" he wondered. "Is this some kind of oubliette?"
He searched upwards with his eyes, daring to increase the brightness of his horn, but still he could not see the next level. At last he looked back towards the door.
"Well," he thought. "It's closer… I'll just check what's beyond the door first."
He crept up to the door and listened to it carefully, holding silent for several moments. At last, hearing nothing, he stepped back and drew his sabre with his magic. He focused on the door and the glow of his magic surrounded the knob as he carefully turned it, then pulled the door open slowly.
The corridor beyond was dark and ornate, and he stepped through the doorway into it. He moved carefully so as not to let his hooves announce his presence on the hard, polished floor. He dimmed the glow of his horn as much as he could, his sabre ready as his eyes studied the corridor.
There was no motion, just a long dark corridor lined with richly ornate décor. He advanced slowly, his ears forward as he listened for any trace of motion, but there was nothing. Suddenly there was a flash of light behind him. He whirled abruptly as a familiar voice called his name.
"Sterling Honor!" called the voice.
Sterling's eyes widened as he realized the source of the voice and the source of the light were one and the same. Princess Celestia was walking towards him down the hallway, lighting it as she did. Sterling lowered his sabre and bowed. "Your Highness!"
"You betrayed me, Sterling Honor," said Celestia as she drew closer.
"You betrayed all of Equestria," said a second voice, disconcertingly close behind him. He spun around again to see Nightmare Moon advancing from the other direction. Her magic was fully restored, and her mane swirled above her as she stepped deliberately, her polished armor gleaming in the light that Celestia cast from behind him.
"Y… Your Highness!" he gasped, dropping back into his bow.
"You swore loyalty," said Celestia from behind him. "But then you went and stood by her."
Sterling stuttered, "B… but…."
"You have to choose," said Nightmare Moon, stopping just a few feet away. Likewise, Celestia stopped behind him.
"Choose which oath you will honor, Captain," said Celestia. "Then face the consequences of the oath you betrayed."
"But, no!" cried Sterling. "Y… you have to understand! Ma'am, please!"
"There is no room for negotiation, Sterling Honor," said Nightmare Moon. "Choose now."