"Enough has been lost this day, let us not lose everything."
The Emperor had witnessed their failure. Sombra had not been allowed the time in his thoughts needed to lament that fact when he had been issued his order. Now, though, marching silently along the road to the Crystal Empire, his mind became filled with the knowledge and regret of his disgrace. Emperor Nicholas, The Master of Time, was merciful and wise, but could even he forgive Sombra's failure?
He should have been there. He should have charged to Luna's aid and been there to save her from Celestia. He should, but he had not. Now he was trapped, Celestia and her armies behind him, with only thirteen of Luna's silent and ever-loyal Companions as guards. All that was in his arsenal was his armour - once resplendent and silver - now dulled, dented, and drenched in blood and dirt; his sword - saved from dulling by its enchantments but similarly soaked in blood; and a vague hope that he could reach the Crystal City in time to fortify it and rally his forces.
Emperor Nicholas would grant him no further boons - sure enough even the simple act of speaking to him through the Companions had drained him of his much needed strength. Still, it was not that he deserved them regardless. What he deserved was to face his failure, but his Emperor had given him a command, and who was he to defy his master?
He did wish, even despite the Emperor's command, that he could have remained to face Celestia alone. She was far more powerful than he, yes, but he may have been able to save his people from certain destruction. Even if it cost him his life, it might save countless others further north. But he had his orders. The Emperor's plan was far more important than his wishes - far more important than even hundreds of thousands of lives.
The first evidence they drew near to the Crystal Empire was the snow, replacing the verdant grasses of Equestria. Usually, the ascent into the Crystal Empire was a pleasant gradient, from a thin and crunchy blanket of snow to a thick sheet about as deep as a pony was tall. Coming up, however, especially wearied from battle and flight, Sombra found himself dragging. He liked snow, especially the snow of the Crystal Empire, but there wasn't any chance to enjoy it with the threat of Celestia looming over him, nor his aching legs and hooves.
Even with his conscious effort to stay firm and upright - he could not allow his people to see him bow his head as if he was defeated - he could not help but lower himself. The trek through the mountains would be a long one, able to be completed by the end of the day if they did not stop, yes, but his lack of energy would likely force a wait. He did not know how long they would have, how long the Crystal Empire would have to prepare itself before an attack. If Sombra and his allies could reach the Crystal Empire in a day, then so too could Celestia. Her armies might reach the Crystal Empire mere hours after Sombra, by which time he still would not have fully recovered and the city's garrison would have made only the most basic of preparations. Or, on the other hand, it could be weeks or even months before Celestia could rally up an adequate response - if she even did at all - or, perhaps, she thought that Sombra was far more prepared than he was. Perhaps, as Sombra hoped, she was as battered and weary as he was. The best way to stop Celestia would be to tire her out.
At the very least, Luna's Elite Guard - who had given their entire force for a rearguard - would buy him some much needed time. Time would continue to be his biggest adversary. With enough time, he could do anything. The Crystal City could be impenetrable given enough time to prepare. But, he did not have infinite time, nor did he likely have even an adequate amount. He did calculations to keep his mind off the pain in his hooves, thinking on how he might be able to resist Celestia with an amount of preparation time he would probably have.
With preparation time of a few weeks, he could mount a defence for a few weeks. But, with the maximum of days he likely had, he could likely hold out for three days at most. Supplies weren't a concern - the Crystal City had enormous stockpiles built beneath it - given the ever present threat of a blizzard; the concern was simply one of fortification, though the Crystal City had walls, they were no where near up to an effective standard. The moment Celestia, or a suitably large contingent of unicorns, took to the field, the walls would be breached and then it was only a matter of time before the city fell.
Time. There were another few hours before they reached the Crystal City. The only noise came from the ever present wind and Sombra's low breathing - with Luna's Companions continuing their infamous silence. Sombra wished they would speak, even just to tell him to stay calm.
Even if the Companions could speak, then what would they say? Would they blame him for Luna's demise? Or would they still just remain silent? Why couldn't Luna's Elite Guard have come with him instead? Why was he even complaining? What did it matter, ultimately, so long as he reached the Crystal City and got the defences sorted?
How long had he been walking? Hours? Days? How many hours or days? His legs felt so light. It was as if he weighed nothing at all. He hadn't felt this spritely since his youth.
A voice cut through the pervasive wind. "Get King Sombra to the Palace, get Doctor Glow to attend to him."
It was all quiet and dark after that. At least he was able to rest.