She awoke peacefully under Celestia's wing. The cushion beneath them was stained with Celestia's tears. "Sleep, sister," she bade, placing a kiss by her horn. She got up and walked to the balcony. The stars were out, but the moon was still down. She took a deep breath and cast a spell that she hadn't cast in a very long time.
The moon slowly rose, deep red in color. It was like raising a flag to half-staff; this way, all of Equestria would know that something tragic had happened. But they would never know what it was.
She retired to her room and fetched a quill and an inkwell. She sat at her desk and dipped the pen, putting it to paper.
Dear Princess Celestia,
Today, I learned that forgiveness is more than saying that you're sorry. I also learned that it's not very smart to judge a book by its cover, because you won't know what's inside unless you read it.
Nopony deserves to be tortured, no matter what their crimes may be. I had a chance to meet the real Discord, the one who still loves you. He sacrificed his life to save mine, and you need to take that into account.
So next time you decide to torture somepony, think twice. Consider him, not yourself.
Your sister,
Princess Luna
She rolled the paper into a small scroll and sealed it with a red ribbon and a spot of golden wax. She debated leaving it on Celestia's cushion, but she opted at last to give the letter herself the next morning before bed. She shut the letter in her desk and pulled on a black cloak and hood before walking out to the garden, where the statue of Discord stood. On her way, she plucked a single rose of an appropriately dark shade of pink, and she tied a few sprigs of rosemary to it.
"I will always remember what thou hast done for me," she whispered, setting the flowers at his feet. A pink rose for gratitude. Rosemary for remembrance. Several tears fell from her eyes, moistening the marble. She knelt at the statue's base and began in verse:
Unfairly kept at wingtip's reach as centuries slipped by,
Yet rancor entered not into the sanctum of thy heart.
I wish upon the blessed Moon to know just who thou art,
But ne'er again will life be seen within thy chiseled eye.
Thy sacrifice without a want for safety of thine own
Will ne'er be absent from my mind, unto the end of time.
And what became of thou I'll wonder ere the Sun doth shine,
Each night when I have raised the Moon and on us it has shown.
To honor thine brave sacrifice, a day will be bestowed,
In honor of forgiveness and of kindness of the heart,
In honor of the price thou paid, the one thou truly art.
But never will I e'er forget the debt to you I owe.
After a few moments of silent reflection, she stood again and shambled back to the palace. She saw somepony in the shadows, but who it was didn't matter much to her. Even if it was somepony plotting something sinister, it wouldn't be of any consequence.
She got back to the palace and lay down on the cushion next to her sister, stroking Celestia's mane with her feathers. She was glad to be back in the real world, back in a place where she could be at peace. Even if for just this moment, everything was good, everything was right. And she couldn't be more thankful for what she had.
Several hours later, Celestia stirred; dawn was nigh, and it was time to raise the sun. After exchanging a brief sisterly kiss, Luna trotted off to her room and retrieved the letter she had written. She hoped that it would somehow sway Celestia and make her see the light.
After Celestia finished raising the sun, she turned around and saw Luna carrying the letter. "What's this?" she asked quizzically.
"Doesn't Twilight Sparkle send you these whenever she learns something about friendship?"
"Yes," Celestia replied, "but you don't have to send me a letter; you could just tell me yourself."
"I figured that it would be a bit more 'official' if I put it in writing."
"Well, then, let's read it, shall we?" She broke the seal and unrolled the paper, and her expression quickly turned from one of amusement to one of exasperation. "Really, Luna, what is this?"
"Something I learned about friendship," Luna sassed.
"Are you trying to convince me that imprisoning Discord was wrong? Would you rather have the world in chaos?"
"I'm just saying that you may have misjudged him."
"Luna, I did what was right."
"By torturing the one who still loved you?"
Celestia's impatience began to grow. "I don't regret my decisions. And because of them, we're all much, much safer."
"Because of your decisions, I almost lost my life! Did you read the whole letter?"
"I didn't see the need," Celestia replied bluntly, rolling the paper back up and replacing the ribbon closure.
"He sacrificed his own life to save me. That has to count for something!"
"It doesn't mean a bucking thing, Luna!" Celestia bellowed.
"What doesn't?" Luna asked accusingly. "His life? Or mine?"
"Luna...."
"No, don't answer that question. I'm going to adjourn for a while."
"You can't do that, Luna. You have responsibilities."
"Really? You seemed to be doing a fine job while I was imprisoned on the moon for a thousand years! What's another week? Next full moon, I leave."
"Where will you go, Luna?"
"Somewhere, anywhere! Anywhere you aren't."
"Then go. Either way, you shan't sway me. Imprisoning Discord in such a fashion was the right thing to do."
"So you say, sister. So you say." She turned and walked indignantly out of the room, returning to her quarters.
When she arrived, she saw a note lying on her bed, along with a single rose of a certain shade. Dark pink for gratitude. She picked up the note and read it.
Long before the shadows fell, you lingered in my mind.
Long before my prison-hell, I knew that I was blind.
You showed me how to live again, and now I clearly see
That blessed hope, the tunnel's end. I give my thanks to thee.
Discord