This far north, Princess Luna could see the Aurora Borealis. Luna herself had created this dazzling masterpiece of nature thousands of years ago. It involved the light of the stars reflecting off the northern crystals and the clouds to create a stunning display of color.
When Luna had been on the moon, she was sometimes able to see the colors from the northern lights. The part of her that had been Luna felt homesick at the sight; the part of her that had been Nightmare Moon just felt infuriated.
Tonight, though, the lights were not moving at all. The sky was an unmoving, dull, dark red. Princess Luna hovered in midair as she pondered this.
"What happened to the clouds?" she asked.
"Luuuuna," a deep voice said.
Princess Luna almost fell out of the sky in shock. "Sombra?" she whispered.
The previously-still clouds began to condense, forming what appeared to be a tornado. The reddish color of the sky took on the shape of a wicked, scythe-like horn.
"Grah..." a deep voice said, as two vague eye shapes appeared in the dark clouds, under the horn. The strong winds that were moving the clouds suddenly hit Luna, forcing her to flap her wings rapidly to remain in midair. To make matters worse, the winds brought falling snow along with them.
"It takes more than shadows of the past to frighten me!" Luna said, shooting a burst of magic at the shadows. It did not seem to have any effect whatsoever; the shadows kept move forward, closer to the princess.
From a distance, Luna could hear Shining Armor shout something, but she could not hear it clearly over Sombra's voice.
"Grah raugh rrrr crystal..." the shadow said. "Raurrr..."
Luna shot out more bursts of magic at the shadowy Sombra. The shadow clouds stopped moving and stood still, about ten feet away from Luna. The eyes narrowed, as if sizing her up, then they widened in recognition.
"Nightmare...." Sombra groaned.
"NO!" Luna cried. She charged up a double-powered attack and let it fly, right at Sombra's face. The shadows and clouds instantly dissipated, although if you looked closely, you could see the dark remnants traveling to the south, towards the train station where Twilight and her friends would soon arrive.
Luna landed on the ground and caught her breath. "Sombra..." she said to herself.
Then she stood up to her full height. "Ha!" she said. "Is that all you can do now, villain? Appear in clouds? That doesn't frighten me! I am Princess Luna, ruler of—!"
A small squeaking sound came from the snow near Luna's left forehoof.
"Aaaa!" she shrieked, jumping back instinctively before seeing that it was just a snow rabbit. She let out a sigh of relief, then glanced around to make sure nopony saw that.
It was not much longer when Princess Luna flew through the barrier which protected the Crystal Empire. Outside the barrier, it was harsh and cold. Inside the barrier, it was bright and cheery, even if the residents seemed to be out of sorts.
Luna spent a moment looking at the Crystal Castle. She could remember when it was first constructed by an architect from Prance. He called in the Neighffel Tower, and it was designed to be a tourist attraction. The highlight of the attraction were the various restaurant levels near the top; ponies loved to eat meals and look out at the entire empire through the broad windows.
When King Sombra took over, he forced his slaves to convert the tower into his personal palace. That meant getting rid of all the restaurants and replacing the high-speed escalators with a giant staircase, for reasons nopony but himself knew.
Luna guessed that Princess Cadance would be in the Crystal Castle, so she flew to the balcony and entered the throne room. There, she was happy to discover her guess had been correct. Cadance was seated on the throne, and she looked exhausted.
"Hail, Fair Princess Cadance!" Luna said.
Cadance wearily opened her eyes and smiled weakly. "Hail, Princess of the Night," she said. "What bringest thee into our domain?"
"We have come to assist thee in the protection of the empire and the vanquishing of King Sombra," Luna said proudly.
"Thine royal help is greatly appreciated," Cadance said.
Princess Luna chuckled. "It's thy, not thine," she said. "Either way, let us dispense with the formalities. I have a feeling you don't need them right now."
Cadance chuckled. "Thanks," she said. "I don't like all those hoof-kissing ceremonials, anyway."
"You look exhausted," Luna said. "What's wrong?"
"It's the shield spell I'm using to support the barrier," Cadance said. "I don't know how Shining Armor can do it so easily. I've been doing it for twenty hours straight, and it's exhausting."
"I believe he will return soon, with his sister and her friends," Luna said. "He can take over for you, then. And as always, I can watch the night."
"Thank Celestia," Cadance sighed. "Speaking of, she sent a letter for you."
"Oh?" Princess Luna asked.
Cadance gestured towards a scroll which was leaning against a pillar. "It arrived about an hour ago, along with a note saying that you were coming here," she said. "She seemed...upset."
Luna used her magic to pick up the scroll and read it, while Cadance lay down on the throne. There was no mistaking it; Princess Celestia was upset. "Hmmph," Luna said. "Not a friendly letter at all. You need to return at once...irresponsible...forced me to raise the moon—what? Raise the moon? But it's nowhere near sunset!"
"That's because we're north," Cadance said.
"Oh...yes, I forgot that the nights are longer in this part of the world," Princess Luna said. "I suppose that means I did miss sunset tonight."
"It's the other way around," Cadance said.
"Excuse me?" Luna asked.
"Not sunset, sunrise," Cadance said. "This time of year, night lasts about a half hour."
Luna's jaw dropped instantly. "This is a horrible, horrible place," she said.
Cadance chuckled weakly.
"I fear this may weaken my magical powers," Luna said.
"That's almost certainly going to happen," Cadance said. "I'm using my magic to spread love and light, but since the crystal ponies are being so cold and distant, it's not working as well as it should."
"The barrier seems to be holding well so far," Luna said. "Your husband and the others are coming soon. Do not worry. All shall be well."
Luna stayed in the throne room and greeted the Elements of Harmony as they arrived. Together, they agreed to spend the next day, getting information from the crystal ponies.
Princess Luna had to try hard not to snicker, when she saw Shining Armor's horn. She knew that he had been attacked by Sombra, but it looked more like he had a bad case of hornpes. That was a disease which usually afflicted particularly rambunctious stallions.
After dining for the night, Princess Luna went to find quarters for herself. Cadance and Shining Armor had the royal suite, of course, so Luna claimed the next-largest room. Once she was satisfied, she sat on the bed and began correspondence with her older sister.
It wasn't pleasant; as Luna soon found out, Celestia had a hidden agenda for sending Twilight Sparkle to save the Crystal Empire.
I know the two of us could easily defeat Sombra, Celestia wrote. And that is what we will have to do, should Twilight and her friends fail. But that is not the point of this mission.
Luna felt that her sister was taking too large of a risk, but she agreed not to interfere with Celestia's plan. Twilight and her friends had proven themselves capable in the past; Celestia was sure they would succeed again.
Speaking of the Elements of Harmony, their leader knocked on Luna's door.
"Come in," Luna said.
Twilight Sparkle opened the door halfway. "Um...Princess Luna?" she asked.
"Ah, Twilight Sparkle," Luna said. She put her letters aside and got off the bed. "I apologize for how I acted towards you earlier today. My sister says I can be quite grumpy whenever I wake up before five."
"That's okay; I wasn't upset," Twilight said. She walked into the room. "I actually wanted to ask you about something else."
"Yes?"
Twilight's eyes went back and forth across the room. "This is, um...kind of weird, but...are we related?" she asked.
"Related?" Princess Luna asked. "What a peculiar question. What would give you that idea?"
Twilight looked embarrassed. "Well, my brother says you called him a family member, and..."
"Oh," Luna said. She laughed slightly. "I was speaking of the royal family. Now that Shining Armor is a Prince, he is a member."
"So, you and I aren't...?" Twilight asked.
"No, we're not related," Luna said. "Celestia and I have no blood relatives, save for each other."
"That's what I thought," Twilight said. "I just wanted to make sure."
Luna took two steps towards the window, a thoughtful look on her face. "I am sure you already know this, but family is not necessarily defined in terms of blood," Luna said. "For example, your friends are a kind of family, are they not?"
"Uh huh," Twilight said, nodding. "Applejack says that we're honorary members of the Apple Family."
"Exactly," Luna said. "I am glad your brother is a good pony, Twilight. Usually, the only ponies who want to become honorary princes are scoundrels like Blueblood or Sombra."
"Sombra?" Twilight asked. "You mean, King Sombra? The one who's attacking us?"
"Yes, of course that's who I mean," Luna said. "Didn't Celestia tell you about that? Where King Sombra came from?"
"No, she didn't," Twilight said. "Did you know him?"
"Yes," Luna said darkly. "Sombra...was my student once, like yourself and Princess Celestia. I cared very much for him."
"Oh..." Twilight said.
"But his pride and ambition got the better of him," Luna said. "One day, he asked—no, demanded—that I make him a full prince. When I said it would not be proper, he grew angry and cut off all ties to me and my sister."
"I'm sorry," Twilight said in a small voice. "I didn't know."
"It's not your fault," Luna said. "It was a long time ago, and...well, that was the last I ever heard from him, until ten years later, when he declared himself King of the Crystal Empire."
"That's terrible," Twilight said.
"Let the story of Sombra serve as an example to you, Twilight Sparkle," Luna said seriously. "Never let personal glory get in the way of doing what's right. A heart that is free of evil will always be a sure guide."