Celestia's dreams took her on a journey through time, beyond time, before Equestria, into memories that were nothing but shimmering fragments of what they once were. The days of a young world, thousands of years past. The days when a certain white-pelted alicorn was still a tiny filly, and her periwinkle coated sibling an even tinier one.
The details were fuzzy, the passage of time having erased much of the finite from her dreamy haze of a memory. The air seemed to sparkle with light, the sun was in the sky, shining down it's warmth as the two of them pranced through a field of flowers, the laughter of her young sister like the tinkling of sweet bells to her ears.
Celestia twitched in her position on the bed, a smile twitching across her lips as her eyelids fluttered as she entered a deeper sleep.
The dream was pleasant, and it filled her with a soft sense of peace as images of her dear sweet sibling, her baby blue hair bouncing as she ran, her tiny frame a treasure.
"WHY DID YOU LEAVE ME ALONE?!?" everything flashed black, flickered back to the golden sparkles.
Celestia jerked to a halt, her hoofbeats ceasing as her sister continued her slow, toddler gallop moving away from her.
The dream Luna turned her head slowly to Celestia, and what appeared to be at first a smile turned into a dark, twisted snarl, "How could you leave me for a thousand years?!"
Again, her dream flashed a dark black and she stumbled backwards, her eyes stretching wide and filled with tears, "No....Luna...I..."
"You betrayed everything we built..." the tiny, sweet Luna was fading away, her pelt darkening, the sky twisting into darkness as her filly form twisted into a Nightmare version of the mare of darkness...
"Luna....No....I didn't...I had no choice...I....I'm sorry!" Celestia was no different in her dreams, her filly form seemed meek and fading before the mighty form of the twisted Nightmare Moon.
"As if I could EVER forgive you!" Celestia chanced a glance up, and now before her was the current, normal vision of her sister, though her eyes glowered a wicked red, "Soon I will rise again! And when I do you...will be the first....."
Celestia backed up further and further from her demonized sister, but found a mighty wall of darkness stopped her, and she found the twisted Luna within inches of her tiny filly muzzle, "TO DIE."
Celestia screamed and covered her head as tears now ran freely from her eyes...the wicked cackling and haunting nightmare Luna swirling all around her.
In her bed, Celestia had broken out in a cold sweat, and tears had formed under her eyelids, her hooves twitching and ears flicking randomly.