The Saviors of Harmony
Prologue
Ten days before it happened, an old blind mare appeared in Ponyville.
She spoke of the day when the sky would shine with the light of both day and night. The light would not be good, but evil, because why would both sister's domains try to dominate the sky at the same time if not for some evil purpose? Hardly anypony stopped to listen.
Five days before it happened, the sun and moon suddenly refused to move from the sky.
The old mare continued to speak. Darkness was coming, nothing could stop it. Nothing, not even the Elements of Harmony. More ponies began to listen to her words, and word of the princesses' silence spread across Equestria.
Three days before it happened, the bearers of the elements, along with the baby dragon Spike, heroically traveled to Canterlot.
None of them returned. As the old mare continued to preach, even more ponies began to listen.
The day before it happened, Spike stumbled back to Ponyville.
Beaten, bruised, and exhausted, the little dragon only spoke once sentence before falling into unconsciousness.
"The two have become one, and the six lights have gone dark."
Now everypony listened to the words of the old mare, even though she had long since retreated to the Everfree and no longer spoke.
The day it happened was the day everypony understood.
An Alicorn appeared, her form flickering between two different tones. One black and the other white. She bent the cosmos to her will and forced everypony to their knees with merciless brutality.
She was the One, and no other. The six extinguished lights pounced upon the land, spreading the One's influence with unholy speed.
And so the little ponies fled to the Everfree forest, escaping their home of Equestria, for it was Equestria no more. The old mare was waiting for them within the trees and spoke again.
"Not even the Elements of Harmony can stop The One now, but you cannot expect the elements to stop anything when they are no longer harmonized."
She scanned the crowed of ponies, her gaze was scrutinizing even though she could not see. Then she began to walk away, fading into the trees like a ghost as her voice echoed hauntingly.
"Who is brave enough to save those who will save us?"
She disappeared completely as Canterlot Castle filled with blinding light. After the light faded, a towering, twisted citadel stood in the Castle's place, its spiked peaks mocking everything the ponies had held dear.
Five years later, it still stands as a pinnacle of despair for all those who dare lay eyes upon it.
After so long, who would rise up to fight back now?