Note: So I did end up writing a second chapter. But it wasn't the chapter I planned on writing, so it looks like you'll be getting a third chapter soon.
II
Gone
And then there was nothing.
The air felt colder here. Different. Luna didn't mind that, some part of her relished cold, for it came with the night and with her freedom.
But tonight it came, settling into her fur and feathers, to grace her forlorn cage.
Luna had always thought that her moon, if nothing else was, would be a place of love and gentle beauty, drenched in soft light. She thought that being part of it would be the greatest feeling in the world. But her moon was barren.
Barren and cragged like her thoughts.
Luna strained, pulling free from Nightmare Moon's consuming hold. The separation was painful and left a cavernous feeling of absence in its wake. And then the shadow mare was facing her, those unsettling eyes stark against her black shape. Luna's immediate reflex was to join with her again, to use Nightmare Moon as a barrier against the onslaught of depression, but she resisted it, needing to establish a sense of her own self at the moment.
For a few minutes, she breathed heavily and noisily, looking for words.
"I-I…" she faltered.
"Look at what your dear sister's love is worth," the mare hissed. "Look upon this place, let your eyes become accustomed to it, because your sister will never willingly allow you to leave." She swept around Luna, a swirl of darkness.
"Celestia loves me." Luna insisted, her heart hurting.
"If this is love, then let's see how long it endures. A year? One Hundred? Can it last for a thousand?"
"Y-yes," Luna said.
"Because that is how long you will wait. And it will be by your own power alone, and not your sister's love, that you will be freed."
And so Luna waited.
The first year was lightened by hope. The days blended into one endless night, strung together by the unrelenting darkness, but amidst all of that was Luna's certainty that Celestia did love her and that Celestia would let her go after she'd had some time to ruminate on what she'd tried to do. As if her banishment to the moon was one very long time-out.
In the second and third years, her hope began to fray at the seams.
By the fourth, or maybe it was the seventh, despair had already crept back into her mind.
The rest of the years loomed ahead of her like a long shadow. The moon was big and beautiful even like this, but nothing happened here. Nothing but another day to live and sleep and chase useless thoughts to the horizon where no matter how hard she strained herself, Luna could never see beyond. Equestria- the world- was lost to her.
Luna tried to busy herself with imagining how time was passing there. She imagined everypony going about their lives, but then the sun pushed its way into the skies of her thoughts and that dream soured, too.
Boredom fell upon her like an oppressive cloud. Each day was marked only by hours and hours of tedium. Luna soon forgot the measurement of an hour, then that of day and night, and eventually she forgot the meaning of a year until the only quantity of time remaining was eternity.
"I wish I was dead," Luna told the shadow mare.
"You cannot die here," the mare said. "You are neither able nor willing."
"I am willing."
"I will not let you die." The mare's eyes shone with fierce determination. "You must exact vengeance on all of those who wronged you. And we must cast the world into endless night."
"I promised myself I wouldn't weep until Celestia freed me," Luna said after a long pause. "But that isn't going to happen, is it?"
"No."
Luna buried her head in her hooves. Her body began to shake, but the tears didn't come, and she wept without weeping. She thought of that distant night beside the ocean. She forgot why she hadn't jumped after all.
"I can't," she whispered. "The emptiness will never go away, and I can't live with it anymore. I can't, I can't, I can't."
Minutes passed, or maybe they were days, or years, or centuries.
"Please," Luna pleaded to the shadow mare for the second time.
The mare said nothing. She merely leapt nearer, and the almost-warmth of her shadow form surrounded Luna like an embrace. Luna lingered in it for a moment, basking in the closest feeling to pleasure she'd felt in a very long time.
"No more loneliness," she thought, all wrapped up into one being, into Nightmare Moon.
"Fight the rage if it keeps you alive. Or don't, if that's what you live for." Nightmare Moon said, her voice ringing cool and clear in the empty air.
Luna didn't fight. She let the bitterness crawl through her, electrifying her, washing over her in a wave of wrath and resentment.
Slipping away further and further. Gone.
Luna didn't remember time; she didn't remember monotony. There was only painful sweet rage and revenge. There was only giving and giving until she'd given all of her strength, all of her feeling, all of everything she had left, she'd given it up to Nightmare Moon.
And then, when the paths of the stars wound into alignment, when the first of them brushed against the surface of her cold, beautiful, desolate moon, Nightmare Moon descended the blazing bridge of light to where her kingdom awaited its dark queen.
