…And as the white alicorn landed upon the cliff’s edge, wings drooping with exhaustion, she turned back to look at the moon; before where it had been completely white with a few stray grey spots, now lay a distinct formation outlined in the shape of another alicorn’s head. Celestia had just successfully sealed her sister - nay, Nightmare Moon - into that glowing sphere, which appeared to be glaring down at her in contempt.
A single tear rolled down her cheek. Celestia had wanted to avoid conflict, but alas; she was left with no other options, and thus was forced to banish her own dear sister from Equestria. The thought of ruling alone for years to come only increased her anguish and sorrow.
Then suddenly, her mane began to change. Pastel blues, greens, and aquas erupted from her roots, merging with the pinks and rapidly becoming more aura-like. The new colours faded near the ends, but the pink continued onwards into the night sky. An aurora borealis formed in the air above Celestia; a tribute to her fallen sister, and the mark of a new era with a single ruler.