A single purple-grey cloud hung low in the sky: a bruise against the amber sunset. The arc of the sun sank below the horizon, caressing every waking creature with its last golden rays, and a promise of tomorrow. A final flash of green took the world into an indigo twilight.
The moon had yet to rise. Still, the stars appeared, one at a time, preparing the night sky for their Lady’s charge.
Timidly, as in every night before, the creatures of the dusk and gloom began to stir, and stretch, and sing. Slow to begin in the cool spring air, the cacophony rose, filling the shadows with life. But it was not to last.
Beneath the croaks, calls, and chirps there began a low rumble, a quaking, and then a mighty roar that obliterated all noise before it. The forest thrashed violently, the ground tore asunder, and the lakes overflowed their banks. Its intensity built, its power raged, and when the very trees began to split...
It ended.
Silence.
The forest cowered, waiting for the next blow. It came in the form of a spark, somewhere in the center of the wood, in a palace of stone, where there lived two sisters.
The spark flickered, and fell, fading, from the horn of the Night Mare. Beneath her, restrained by ancient magic, Celestia watched in horror as the faintest wisp of eldritch power drifted to her horn, and was absorbed.
The world vanished in pure light. A torrent of energy, wild and savage, erupted from the captive alicorn, blasting away the walls of the palace, and vaporizing every living thing for miles - plant, animal, and pony - in an instant.
Standing in the center of the sun’s rage, what was once Luna channeled her sister’s power into herself. The radiant energy was harnessed, and shaped, slowly, into a blinding column. It tore through the sky, and into the waiting night. The days-long battle was over.
The Moon Princess smiled. She did not need her sister any longer. Taking the tiniest fragment of the sun’s power, she drove the unconscious alicorn into the bedrock below. Setting to work, she channeled again, focusing the myriad streams of energy into an ever-intricate net that she cast across the sky. The energy pooled there for the slightest of moments, then coursed for western horizon.
Something changed, then, and brought with it a strange sensation: a sound that was not heard, a pain which could not be felt, a loss that could not be understood. The sun, buried past the horizon, was chained in place. Triumphantly, Nightmare Moon bellowed her victory, and set the moon in its rightful place at the apex of the sky.