"Luna!" Celestia's call for her sister came sharply, and might would have made any other pony scurry for cover. Luna, however, was never far, especially since she too lived in the same castle. Not much went on without either of the sisters anyways.
Luna strode up to Celestia, feigning to be just waking from a nap. Her massage therapist had done wonders, wonders so great that it was obvious that she had not taken that trip up to the Crystal Empire as she had claimed that she would. Seeing her sister as enranged as she was actually got her heart to racing. If Celestia was angry, heads were going to roll.
"Sombra had the nerve to reject my invitation?" Celestia fumed, still pacing the clear out throne room, "And suggest that I go to him instead? Has the stallion lost his mind?"
"Among other things," Luna joked, "Your most faithful captain has clearly taken advantage of the situation."
"Word among the Guard has spread that it is him," Celestia lamented, "If he destroys the crystal ponies, Equestria will have to face the political ramifications of provable genocide! Luna, we have to do something."
"Ransom his wife and then kill him upon compliance?" Luna suggested, "Might be a bit messy, but it is straight to the point."
"Sombra bathed an entire city-state in green fire out of fear for his life and the life of his subordinates," Celestia mused, "No telling what he would do if he thought that his wife and foals were in danger."
"So what do you suggest?" Luna inquired, genuinely curious, "If we march on the Empire, Sombra will resort to drastic measures to prevent capture."
Celestia looked to Luna, determination in her eyes. "If he wants to rule the north, then he should first learn how to live in it; we shall banish him there."
Luna seemed taken aback at the suggestion. "Banish him? Wouldn't killing him be better-"
"If we are wrong and Sombra has contracted some condition due to dark magic, then forever the guilt would haunt us if we were to end his life without trying to help him," Celestia explained, "At least if we banish him it will give us time to assess the cause of this rebellious behavior."
Luna would have objected, but Celestia had already set her mind to it. And there was no changing her mind once it was set.
"My lord!" one of the crystal guards came rushing in, panting heavily as if he had been running for at least an hour, "There, is-"
"Catch your breath," Sombra ordered, perched on his throne in a disinterested fashion. He had seen very few visitors since the guards had left to give his answer to Celestia, and the hour was approaching quickly.
A few minutes past before the stallion made his report. "Equestria's Princesses have been spotted making their way here! What should we do?"
Sombra pondered it for a moment. This was, of course, according to plan, but he would have expected Luna to give him endgame details before the time came. Of course, she rarely gave details early, this mission's history had shown that, so Sombra dismissed the troubling thoughts. "Let them come. We shall meet them on the balcony."
The crystal guard bowed and departed, perhaps a bit too excited at the coming news. He and the others would receive their freedom soon enough, they likely felt.
Waiting in his throne room, Sombra felt an odd calm about the upcoming ordeal. He neither felt worry nor extreme concern. But he was not excited either, and that is what mystified him the most. He should be thrilled that his last mission was about to come to a close. That he would not have to worry about slaving away in some mine or low class shop just to pay for his retirement. Not every pony could say that with confidence.
He could spend the rest of his days with his loving and most faithful wife and his two young foals. He could watch them grow up, start their own journeys, and add on to the herd.
Something nagged at him though, something that told him that his lack of excitement was intuition. No sooner did his thoughts wander did the entire room darken, as if the sun itself had taken a quick break behind a giant shade. On guard, Sombra rose from his throne, only to see Luna materialize from the darkness, her face showing extreme concern. She stood just in front of the double doors, slowly approaching as she no doubt realized her projection was a bit far from her target audience.
"Sombra, why are you not making preparations?" Luna inquired, "You appear hardly concerned at all."
Sombra chuckled, for if the mare could read minds, she would know that it was not mere appearance. He really was not all that concerned. "I am not concerned. I am going to lose anyways-"
"You should at least bring the Crystal Heart for good measure," Luna insisted, her projection wavering, "We want this to be as realistic as possible. You are to be standing on the balcony, not moving from your place regardless of any flashing lights from my sister and me that may suggest something requiring you to move."
Sombra scoffed at the first portion of direction. "I have the Heart hidden away; consider it backup in case the crystal ponies do not take too kindly to your intervention. They may be slaves now, but if they get wind of what is going on-"
"Your job was to make sure that they do not!" Luna strode up to Sombra angrily, temper clearly rising, "We can use that Heart to force them into submission again."
"Actually, that would only make them stronger since it is their magical artifact after all," Sombra pointed out, "I have no doubt that you two could carry out the job without the Heart."
Sombra's refusal to relinquish the heart, much less reveal its location, had clearly gotten under Luna's coat. However, she seemed to be showing restraint in unveiling her anger, and Sombra had to note that this made her seem more like a princess than ever before.
"We can, but I need the Heart secured before we get here in the flesh," Luna pressed, "It is very important to me."
"What says Celestia on this?" Sombra inquired, "She rejects my letters, and then sends guards to demand that I leave the Empire. Doesn't she realize that would spoil the plan?"
"Celestia had to build up some pretense before rushing here." Luna seemed patient enough to explain this, despite the somewhat common sense principle behind it. "She could not just up and decide to find you here randomly. Either way, I am done asking Sombra, I demand that you bring the Heart with you when you go out onto the balcony."
"No."
Sombra was resolute on this. If the crystal ponies suspected that they were trading one tyrant for two, then they would rally together and, in the presence of the crystal heart, have the power to threaten Equestria. Celestia and Luna's only options then would be to use force, which they could have done without going through the trouble of planting him in the middle of this. That would defeat the purpose of the whole mission.
In part, their suspicion would have arisen from the little explained fact that Sombra did come to power under very questionable circumstances. The death of their previous ruler and the subsequent subjugation of the Guard may have been swept under the rug with the chains of bondage, but it had not been forgotten outright. Not to mention, again, once the ponies found out Luna's job of defending the night and the realm of dreams, they would no doubt put two and two together.
No, Sombra could not risk giving the instrument of their demise. Why could Luna not see this though? If he did not know any better, he would have suspected that Luna wanted to risk unraveling the entire plan.
Luna sighed, her projection once again briefly fading before returning to its full color. "Fine, have it your way. But I will have the Crystal Heart at the end of this. "
Her form vanished, and the lighting in the throne room returned to normal. Sombra's mind picked up on the not so subtle threat at the end of her statement. Luna wanted that Crystal Heart; and whether Sombra gave it to her or not, she was going to get it. Of course, if she obtained it, then so would Celestia. But she specifically used "I".
She apparently had no intentions of allowing her sister to also have access to that power.
Though that was mere conjecture, Sombra concluded that not all was quite right with the plan. Something had happened that had once again caused Luna to deviate. What that meant for him was ambiguous, but it was clear that he needed to be prepared for just about anything. Looking about the castle, Sombra concluded that it would need a visual make-over. The bright ceilings and walls just would not do, as it would contrast sharply with the upcoming scenario to be played out.
Using dark magic, Sombra began to influence the crystals around him. To his delight, they responded eagerly, becoming almost as black as his mane, spreading spires of red and black all over the Empire's crystalline structures. Yes, red and black was a rather stereotypical way to represent power and malice.
"What to do now..." Sombra mused. He still had three hours before the appointed time, noon. Though he tapped his chin for a moment, the perfect time burner came to mind to the stallion. Some of the dark magic that he had spread was slowly beginning to tickle at his mind, reminding him of the possibility that he could end up with an arrow through him. Or worse, a horn half the length of his body that would serve the same purpose.
"A letter," Sombra concluded, "A backup spell, and of course a gift ahead of time for Violet."
30 minutes till Noon
Sombra, never one to be late intentionally was already out on the balcony, casting glances towards the rising sun as he awaited his cue to begin looking menacing. Granted, he had already donned the ceremonial armor that he had come here with and draped a cape over it, so he at least looked like the King that he was supposed to be. The crown on his head did not really fit in this aspect, but that did not matter.
All that mattered now is that he was now in the easiest part of his mission. Before he could bask too much, the slaves below began walking in odd unison, as if they had been given some sort of signal. Sombra peered down below and smiled. Their hopelessness, their despair, all of it would soon culminate into a resounding cheer once Celestia and Luna flew onto the scene. They would be freed from his "tyranny", and each would buck, bay, and whinny in joy for their new rulers.
Sooner than expected, the rays of the sun were graced by the two alicorn sisters. The crystal ponies below paid no heed at this point, but Sombra had his attention almost fully on the two sisters, silhouetted by the giant orb of fire that warmed the day. Seems they were also quite early, or had intended on sneaking up on him first.
Celestia spoke first, always being the larger of the two figures. "Sombra, we have, as you so egotistically demanded, come. And this sight displeases us greatly!"
Sombra smirked, thrusting his chin upward, preparing his loudest bellow. He had been working on the retort for a few minutes now, and he had to say, he knew that the "your displeasure is our pleasure" line would certainly garner some genuine irritation from the princess.
Before he could let loose however, Celestia continued speaking whilst shaking her head. "We are sorry, our most esteemed captain, but the time for your punishment for Trottingbama, among your recent offenses, are long overdue. We shall not allow these ponies' lives to be risked by your continued reign."
Luna briefly shot a glance towards Celestia, though due to the sun it made it difficult for Sombra to read. Right here in front of all of the crystal ponies, she had just mentioned that incident, which also had a proportionately large number of earth pony victims. In front of the audience that had been supposedly in the dark about his identity back home, she had revealed that he was the same pony who had commanded Celestia's army during that particular incident.
And it was here that fear gripped Sombra, as Celestia's body language all pointed to one thing. She was not joking, she was not putting on a show; as Luna's temporary reaction had shown, Celestia was dead serious. Which meant that Luna had likely not told her about the plan. Either that or they had made a change of plans without telling him.
And Luna had no intentions of divulging the plan either if the former were true, for both she and Celestia began channeling magic to a central point. Terror unlike anything the stallion had faced before gripped him, his thoughts and magic reeling. He was prepared for Luna's betrayal; his last thoughts, and that curse ready to lock away the kingdom. Take away her prize, her loot, her booty, and he stripped her of the success that treachery would have otherwise brought.
But he was not ready for Celestia's betrayal if it was the latter. He was not ready to have to deal with a hostile Celestia either way it fell.
Even as the beam of magic shot towards him, he stayed rooted to the spot on the balcony, the inner guardspony determined to follow orders for some reason. Even if those orders led to his destruction. In a flash of dark magic, the very ground seeping with it, Sombra's body became enveloped in the two's magic, and the kingdom in his.
"Ye shall be banished to the far North for a thousand years as a mere shadow, thine trademark tool of tyranny," Celestia decreed, "For this time, we will not allow ye to do as ye please, for no reason!"
Sombra wanted to cry out at this point, but he found his voice restrained. An addition to the spell it seemed. His body dissolved and turned into a shade, prevented him from speaking intelligibly. 'Wait, was this the plan all along?' came out as "Graaaaaaaaaaaaaah!"
In a wisp akin to a powerful wind, he was swept from the balcony and thrown to the white enclaves of the snow, unable to comprehend the manner in which he had been sentenced. Further and further he went, until all that he could see was a dark crevice, its invitation a cold burst of vapor that nearly froze his face in place. Upon entry, the top slammed shut, and for the first time in his existence, Sombra found his body spread out among the darkness that riddled his prison. His cage.
He cried out, but naught but a ghastly howl was heard. He attempted to literally cry, but his eyes merely produced the green fires of his magic. Despair unlike anything he had felt before took hold, empowering the very darkness that surrounded him. His prison seemed to consume him in this fashion. Sombra began to ponder if he really should have ever trusted that he would get to go home once and for all. That Celestia and Luna would keep their end of the bargain to a pony such as himself.
In darkness, with only the sound of the howling wind as a distraction, Sombra lost all other senses, likely a consequence of his body's deconstruction into that of a mere shade. Festered out of the belief that, no matter which way he crossed it, Luna had betrayed him, cast him in a role that was supposed to only last a week. Only a single emotion could be felt, one that would slowly rebuild a sense of purpose in the discarded stallion.
Resentment.