The last rays of sunlight had long since faded when Celestia alit upon the highest balcony of the tallest tower in Canterlot. She rarely came to this particular corner of her castle; some error in design or construction had left it without a door, making it impossible to access without flight. The princess of the day had little use for the deserted balcony, but she suspected that it was the solitude that had attracted its other occupant. Princess Luna stood across from her, back turned, wings tucked at her sides, head raised toward the heavens. If she had noticed Celestia's landing, she gave no sign.
The white alicorn moved to her sister's side, hooves clopping slowly on the rough stone. "Good evening, little sister."
Luna sighed, continuing to gaze up at the heavens as she responded absentmindedly, "Is it? I do like when the moon is a waxing gibbous. I did my best tonight. I always try my best, but some nights are better than others. Isn't that odd?"
"Sister," Celestia ignored the question, "I haven't seen you at court. You need to come back to the world, learn to live again. You've avoided our subjects so much that I fear your desire for solitude may be consuming you. How long has it been since you've moved from this spot?"
"Since the last full moon, sister. Since the last full moon."
Celestia felt guilt at that; she hadn't realized how time had run away from her. She should have come sooner. Since Luna had returned to Canterlot, they'd spoken only a few times. The regent of the day felt her face fall as she considered ways to reach the sister she'd imprisoned so long ago; the dark mare was close enough to touch, but still as distant as the cold, pale moon.
Even so, the princess of the sun felt as though if she could just find one crack in her sister's shell of bitterness, she could have the old Luna back, the Luna that had loved to laugh. She attacked the problem from another angle, "Why don't you try some sleep? I found it to be a very pleasing experience, the first time I did it five hundred years ago, or so; I'm no longer surprised that most ponies do it once a day."
The princess of the night looked toward Celestia, raising an eyebrow, "I remember when you would have considered sleep to be beneath you. You've become similar to our subjects in so many ways since you imprisoned me."
Celestia answered with good cheer, despite the other alicorn's hostile words, "I gave up on tyranny and on holding myself above them since your imprisonment. Even old ponies can learn new tricks." Her mouth twisted with a wry half smile, which faded as her gaze and tone grew distant. "Being like our subjects is not a bad thing, dear sister, as you well know. The fact that you ate and drank and traded jests and wit, the fact that you seemed like one of the herd while I stood apart, partaking in none of it, that was one of the things that made the ponies of Equestria love you."
"Well, sister, I'm afraid that my wit is somewhat dulled; I am a thousand years out of practice, after all. I believe my verbal jabs leave bruises where once they cut to the quick," Luna smiled, but it did not change the sadness obvious in her eyes, "Loved, did they? In the past. They used to love. I threw it away in a futile gesture that they could never have understood in the first place. Sister, I was moved by your forgiveness, after all I'd done, but if they knew the truth about how things were... I don't know if our subjects would ever be able to forgive me. For what I did then. For telling them now, when it's all so long lost. The love they had for me is a thousand years dead, and it's a far more recent burial than I ever deserved."
The white alicorn turned her head away from her sister to hide the mist forming in her eyes, "I'm sorry, Luna, that they love what I've done for them so much more. I maintained your part of the cycle for a thousand years, but I know that it is the fact that you set things in motion that weighs so heavily upon you, not the maintenance. If I could take some of that burden from you, I would, and perhaps you would never have been driven to such desperation, but you know that I could never have done as you did, could never have given the gifts that you gave." Celestia sighed. "This was always our lot. Only I can give them the gifts of light, and only you could have given them the gifts of darkness."
Luna slowly ground one of her hooves into the rough stone upon which she stood. After a moment, she whispered, "That helps little, sister. If I look at it that way, then I should be condemned not only for what I have done, but also for what I am."
Celestia met the other alicorn's eyes, her stare suddenly intense. "Luna, if you disregard everything else I've said to you, hold on to this: I could never have made Equestria as wonderful as it is, as full of magic and beauty, if you had not been there to shape it beside me. Whatever the mortal ponies feel for you, I will always see you as my equal, and I could not have accomplished this," her hoof gestured in an arc, encompassing Canterlot below and the valley that spread beyond, silvery in the light of the moon, "without you."
"That...," the dark mare paused. "That means much."
"As for forgiveness," the pricess of the day said, "I don't blame you for seeking it, Luna. From yourself or from others. It took me centuries to find it in my heart to forgive myself for what I stood aside and allowed you to do. I only hope that you're a wiser being than I am. If you want to love your place as you once did, sister, if you want to forgive yourself, then connect with our subjects. It is their forgiveness, their empathy, their friendship, their love, that taught me a better way than callous detachment. Their capacity for understanding may be beyond even our reckoning. Centuries ago, when a few ponies found it within themselves to forgive me for the tyranny I inflicted upon them, to be my friends, that was what started to melt the ice in my heart. Frozen things are brittle; they break easily, sister, and the heart is no exception. Think on it. Goodnight." She flapped her wings, soaring away from the balcony; she feared that anything else she said would do more harm than good.
From behind her, Celestia heard a whisper on the wind, "The forgiveness of our subjects..."