Prologue
The halls of Canterlot Castle were busy with construction ponies. A month had passed since the failed changeling invasion on the city, but still, reconstruction was underway on the castle, which had been hit the worst. Princess Celestia found it hard to concentrate and often found herself wandering the quieter areas of the castle where there was no work underway.
'Equestria has faced one crisis after another these past few months.' Celestia thought to herself as she gazed out a window at the city below. Canterlot, as Equestria's capital, was usually bustling with activity at this time of the day. The city streets below, however, were near-deserted, save for a few guard ponies. The changeling attack had left many of Canterlot's residents too paranoid to even leave their homes, for fear that someone they trust, a friend, neighbour, perhaps even a family member, could be a changeling in disguise.
Celestia was all but certain that all of Queen Chrysalis' drones had fled the city with her, but her guards, as well as the citizens of Canterlot themselves, refused to believe that they were safe. Increased security, curfews and even a protective magical dome around the city did little to ease the tension.
The attack on Canterlot came not too long after another crisis. Discord, the spirit of chaos and disharmony, had broken free from his stone prison and wreaked havoc on Equestria for a short while before Celestia was able to re-imprison him. Celestia had wished there was another way to deal with Discord. Turning him to stone was a punishment she felt she was too harsh in giving him the first time around, but it was her only option this time. The Elements of Harmony were not as powerful when wielding all six alone. Maybe she could have helped Discord if she wasn't alone.
'If only she were still here to help.' Celestia thought to herself.
Celestia returned to her throne room. The construction ponies had taken their leave for the day and so Celestia thought it best to take advantage of the quiet and finish her remaining duties.
As she read through her speech for an upcoming event, with the help of one of her aides, the doors to the throne room burst open and a guard came rushing in.
"News from Northern Equestria, Your Highness!" The guard bowed before the princess.
"Yes?" Celestia said as she passed the papers she was holding to her aide. Northern Equestria was an uninhabited region, save for a guard outpost. It had been a long time since Equestria had heard any news from that far north. Could it be....?
"I am simply to tell you," the guard removed his helmet. "That it has returned."
Celestia gasped. "Find Princess Cadance, at once!" she said to the guard. She then turned her attention to the guard standing next to her. "Summon Captain Shining Armor. Tell him that it's urgent."
"Is all this security really still necessary?" Princess Cadance asked her escort as she walked with him through the streets of Canterlot toward the castle. "I'm sure I can walk from my home to the castle without being kidnapped by changelings again."
Flash Sentry was a new recruit to the guard. He hadn't expected to be made solely responsible for escorting an alicorn princess so early into his career, but with the royal guards spread so thin, he was the only one available. "The order came from Princess Celestia herself. I'm not allowed to take my eyes off you until you walk into the castle." He explained.
Cadance rolled her eyes. "Captain Shining Armor's dome has kept anypony from entering the city undetected, and the mandatory identification checks a pony has to go through on every single street corner haven't managed to find a single changeling. I appreciate the sentiment, Private Flash, but I really think all this extra security is just making everypony even more paranoid."
"The Princess' summons sounded urgent, Your Highness. Maybe they really did discover a changeling in Canterlot?" Flash pondered. As the two approached the castle entrance, they had to run through the usual security checks. A guard magically scanned them both, then requested Flash to show his badge. Once that was done, the two entered the castle's reception hall."
"Cadance! Thank you so much for coming so quickly." Celestia was waiting for them. "This way, please. The captain is waiting."
"Thank you for the escort, Private." Cadance nodded to Flash and went to follow Celestia to the throne room.
"We must hurry. Time is of the essence." Celestia exclaimed.
Cadance could tell that she seemed shaken by something. "Is something the matter? Did they find a changeling in the city?"
"I'm afraid the changelings are the least of our worries now, Cadance."
"What do you mean?" Cadance asked.
"The Crystal Empire has returned."
"The Crystal Empire?" Cadance was confused. The name sounded familiar to her, but she didn't remember reading about such a place at all during her studies.
"I'll explain more once we meet with the guard captain." Celestia said. "But what I can say is that if I am right about what I fear is about to happen, the threat to Equestria will be far greater than it was from the changelings, Discord, or even..." She trailed off.
"Really? What makes the Crystal Empire so dangerous?" Cadance asked.
"It's not the crystal ponies who are dangerous..." Celestia grimaced. As the alicorns entered the antechamber to Celestia's throne room, they were met by a guard wearing purple armour.
"Ah, Shining Armor." Celestia sighed with relief. "Thank you for coming so quickly. I'm afraid this is a most urgent matter."
"Of course, Your Highness." Shining Armor bowed.
"This Crystal Empire." Cadance began as they entered the throne room. "You say that it has returned. Where has it been all this time?"
"The Crystal Empire vanished over a thousand years ago." Celestia explained as she sat down on her throne. "Few remember it ever existed at all, and any records of its existence are rare to find nowadays."
Celestia levitated a large crystal onto the ground before Cadance and Shining Armor. As soon as it touched the floor, it began to glow a bright pink, before projecting a hologram of a city. A large blue castle sat in the centre of it.
"The Empire was home to the crystal ponies, and when Princess Luna and I came to power it was ruled by Princess Amore. A few years after Luna and I defeated Discord, Princess Amore vanished and King Sombra came to power."
"What happened to the princess?" Cadance asked.
"I do not know." Celestia sighed. "King Sombra was not a crystal pony, I can only assume he took control of the Empire by force. This could mean that Princess Amore was imprisoned by him... or worse."
The projection of the Crystal Empire began to change. The brightly coloured crystalline buildings began to turn darker, and black crystals grew out of the ground. Eventually, even the towering castle was covered in these dark crystals.
"King Sombra used dark magic to maintain control over the Crystal Empire." Celestia explained. "Without their princess, the crystal ponies fell into despair, and they were powerless to resist Sombra's magic."
"So what happened? Why did the Empire disappear?" Shining Armor asked.
"When Princess Luna and I learned of what was happening, and that Sombra was planning to build an army to invade Equestria, we intervened swiftly. Using the Elements of Harmony, the king was turned to shadow and imprisoned in the arctic north. However, before his imprisonment, Sombra put a curse on the Empire, and it disappeared along with him."
"So, if the Empire has returned...." Cadance began.
"Then it's likely that Sombra has returned with it." Celestia confirmed. She closed the hologram coming from the crystal and returned it to its stand beside her throne. "That is why I have called you both here."
"Shining Armor, as Captain of the Royal Guard, I want you to take a battalion of guards to meet with those already stationed at our outpost in Northern Equestria. If Sombra is planning an attack, we must be prepared to meet him head-on."
"What?" Shining Armor gasped. "Taking an entire battalion will mean Canterlot is less fortified, and if I'm not here, I won't be able to keep the dome around the city. If the changelings-"
"The changelings are no longer our primary concern, Captain." Celestia insisted. "The Crystal Empire poses a very real threat and I must divert as many resources as I can to keep my subjects safe. Do you understand?"
Shining Armor hesitated for a moment, then sighed. "Yes, Your Highness, I do."
"I will remain in Canterlot for the time being and oversee security myself. I will have to join you in the north if the situation escalates, though."
"If you defeated Sombra with the Elements of Harmony last time, can't you just use them on him again?" Cadance asked.
"I'm afraid it's not that simple." Celestia lamented. "Without Princess Luna, the Elements are not as powerful, and on top of that my own connection with them is fading. As we've now seen, the spell that imprisoned him the first time was only temporary, and trying it again may only delay Sombra once more, perhaps for an even shorter period. I have my own suspicions for how we may be able to stop him permanently, but it requires more research into the Empire itself. That is where you come in, Cadance."
"Me?" Cadance blurted.
"Yes. Your power is something Equestria has not seen for a long time. Outside of the Crystal Empire, love magic has always been rare, but your abilities are not dissimilar to that of the crystal ponies. I think you may be able to understand them better than any of us."
"You want me to investigate the Crystal Empire? To find out how we might stop King Sombra?" Cadance asked.
"Only if it is safe to do so. Sombra may be in a weakened state, meaning he might not have retaken the city just yet. I want you to find out as much as you can and report it back to me, so we can begin to formulate a plan." Celestia stood up from her throne. "Are you both willing to accept your tasks?"
Both Cadance and Shining Armor nodded. "Excellent. You shall both leave first thing in the morning."
Cadance and Shining Armor, along with the troops they were bringing to the northern outpost, were being transported by airship to the frozen tundra beyond Equestria's border. Shining Armor reluctantly lowered the dome around Canterlot before leaving, taking almost half the guards stationed in the city with him.
Night had fallen by the time the airship was passing over Vanhoover, Equestria's northernmost city. Cadance sat alone in a room at the very front of the airship, gazing out the window at the town below. Shining Armor entered.
"Princess. The captain tells me we should be arriving at the northern outpost in about an hour." He reported.
"You know you can call me Cadance." She chuckled. "It's just us here. I think us dating as teenagers is enough reason for us to not need titles."
Shining Armor blushed. "That was a long time ago. I didn't think..."
"Don't worry about it." Cadance smiled at him. "If you're not too busy.... why don't you stay a while? The view from up here is beautiful."
"I should really get back to the troops-" Shining Armor began.
"You've been running through training exercise after training exercise since we left this morning. You said we'll be landing shortly, sit down and have a rest for a bit." Cadance insisted.
Reluctantly, Shining Armor removed his helmet and sat down beside Cadance. The lights of Vanhoover below gave a breathtaking view.
"How's Twilight doing?" Cadance asked after a few minutes of silence. "It's been so long since I've seen her."
"She's good. You know my little sister, always trying to learn." Shining Armor chuckled. "She's studying in Fillydelphia. Once she realised that magic wasn't her strong suit, she found she had more of a talent for science. Math, physics, that sort of stuff."
"She was so upset when she didn't get into Celestia's school. I tried everything I could to convince my auntie to change her mind, but she didn't think Twilight had the potential." Cadance sighed.
"She was heartbroken for months but she managed to get over it." Shining Armor said. "I still worry for her sometimes, though. She sends home letters from time to time but she only ever talks about the same things. How she's doing in university, how she's been spending sleepless nights studying for exams. She never talks about what she gets up to outside of studying. No mention of any friends."
"She's always been like that, though." Cadance nodded. "I used to have to drag her kicking and screaming away from her books to come play in the park when I first started foalsitting her."
"You know what I never understood," Shining Armor began. "Was why you started foalsitting in the first place. You were a princess, it's not like you needed the money."
"You're not wrong." Cadance giggled to herself. "I had everything I could ever want living in the palace. The truth is I just loved looking after foals. I used to foalsit in my old village before I got my horn, and I guess even after I moved to Canterlot I never wanted to stop."
"I see." Shining Armor said. "I never knew that."
"Plus," Cadance said, smiling coyly. "I heard Twilight had a super cute older brother."
Shining Armor blushed. He was about to say something back to Cadance when the airship began to shake violently.
At some point during their conversation, Shining Armor and Cadance hadn't noticed that it had started to snow. The flurry had suddenly picked up into a full blown blizzard that was tossing their airship around in the sky.
"Where did this come from?" Shining Armor gasped. "This wasn't in the weather charts." He turned to leave the room, but the door opened and a guard walked in.
"Sir, we seem to have been hit by some kind of blizzard."
"I can see that!" Shining Armor snapped back impatiently. "Tell the captain to land the airship until the storm passes! It's too dangerous to fly in this weather."
"Right away, sir." The guard turned and left. The airship gave another violent shake.
Looking out the window, Cadance couldn't see anything. They had long since passed over Vanhoover and were now probably somewhere in the frozen wasteland beyond the border.
"If we crash out here..." Cadance began. Shining Armor could see the worried look on her face.
"We won't. I had this airship reinforced with a weather protection spell before we left. It won't hold for long in a blizzard like this, but it should be long enough to get us on the ground safely.
Both of them ran to the control room where the ship's captain was desperately trying to regain control. Just as they entered, an ear-piercing screech could be heard from outside the ship, which began to rapidly descend.
"You're bringing us down too fast!" Shining Armor yelled to the captain.
"It's not me, sir! Something out there is dragging us down!"
All that could be seen out the window was pitch black. Nobody was sure how close to the ground they were, or what was dragging the ship down.
"Everypony hold on to something, this is going to be a bumpy landing!"
The ship hit the ground violently. If not for Shining Armor's protection spell it would have been torn apart, but instead the ship's impact sent everypony in the control room crashing into a wall.
It was the last thing Shining Armor remembered.