The following story takes place in a slightly alternate timeline, inspired by the Crystal Empire future in the season five finale "The Cutie Re-mark". The action happens at the beginning of season three, replacing the events in the two-part episode "The Crystal Empire". All events which occurred in the series prior to that episode are unaltered.
"Given the choice, whether to rule a fading empire, or to challenge the fates for another throw of the dice, a better throw against one's destiny, what was a king to do?"
"More than a thousand years ago, I took command of the Crystal Empire, giving it the stalwart and resolute monarch it deserved. In my infinite generosity, I decided to offer its citizens the immeasurable privilege of serving me."
"Feeble and foolish, they refused. Determined not to let anything stand in the way of progress, I turned to despotism and slavery. The end always justifies the means, after all. With boundless pride I watched as my empire grew and relished the thought of one day uniting the whole world under my hoof."
"However, fate decided it would play a cruel cosmic joke. Out of sheer jealousy, and by some twisted miracle, the two alicorn princesses which ruled over the neighboring kingdom of Equestria managed to assault my castle and vanquish me."
"Little did they know of the power that I truly possess. Although my physical body was shattered, my spirit remained unscathed. Before the princesses could do any more damage, I tore open a portal in time and flung my empire into the future, hoping to one day return and take back what was rightfully mine."
"After my resurgence, I was amused to see what awaited me: admiringly persistent, the two alicorn sisters still wanted to take control of my dominion and even sent a young princess and her inept consort to prevent me from regaining power. Their attempts to shield the Crystal Empire from my dark magic were … laughable, and soon I was able to reassume physical form, reuniting my loyal subjects with their beloved monarch."
"As retribution, I released my armies onto Equestria, igniting the most glorious war the world had ever seen. Despite my superior tactics and impeccable leadership, I was unprepared for the new world which awaited me, and condemned to watch as the unthinkable unfolded before my very eyes: the Crystal Empire was losing the battle."
"My enemies displayed an inconceivable amount of willingness to fight on, and with the aid of alicorn magic and their so-called 'Elements of Harmony', they managed to secure victory after victory and push my armies back. Now, only the Crystal Castle stands, the last remaining bastion of my once mighty domain. As I look outside my windows every morning, seeing the tide of Equestrians getting ever closer to my seat of power, I cannot help but wonder if my palace will become my tomb. With but a hoof-full of my most loyal soldiers at my side, the rumors I keep hearing of my time coming to an end seem to be turning into a reality."
"The reasonable thing to do would be to surrender and try to negotiate my survival … but only weak fools do reasonable things. I am not some mere mortal, clawing my way through this world for a few scraps; I am King Sombra, omnipotent ruler of the Crystal Empire and all-mighty lord of the shadows. Against all odds, I shall triumph."
"I will not accept my fate! I choose to laugh in the face of destiny and risk everything on one final gamble, one last throw of the dice. Even though I can hear death whispering into my ear, I choose defiance!"
"But does one every truly have a choice? One can only match, move by move, the machinations of fate, and thus defy the tyrannous stars."