Luna had wondered, briefly, if things could have been different. Maybe if she had tried harder, maybe if she was less aloof, maybe if she had done more to distinguish herself from her sister, maybe, maybe, maybe.
(Maybe if her sister had loved her even a little more)
Then the transformation took hold, and Luna wondered no more.
As Celestia watched her dearest little sister warp and twist before her eyes, she wondered where she had failed. As a leader, a princess, how had she not seen the dark turn her sister had taken? How could she have been so blind?
It didn't really matter, she decided, as the battle dragged on. Luna made her choice, and now Celestia must make one of her own. A kingdom's well-being or her sister's life? The choice was obvious, but in her heart of hearts Celestia wished she didn't have to make it.
(She wished she had been a better sister)
The rainbow beam of the Elements of Harmony converged on Nightmare Moon, and through her tears Celestia could see her terror and pain. The Elements struck true, and after a terrible, wrenching scream, silence fell over the remains of the Everfree Forest. Celestia flew to the ground, deeply exhausted, and looked to her sister's moon, as blank and empty as ever.
Only then did Celestia allow herself to weep for her sister, now lost to her forever.
Nightmare Moon was falling, falling, falling. She could feel her shape changing as she fell, transforming yet again as hooves turned into hands and feet.
It was Nightmare Moon who fell.
It was Luna who woke up.
Notes: This work has been cross-posted from AO3. If you'd prefer to read it there, the link to my AO3 account is on my profile. Otherwise, please enjoy! Enormous thanks to Fiend and Fred for beta-ing this chapter, and to Izzy for helping me figure out a beginning.