Princess Luna flew straight into the throne room of the ruined castle, tucking her wings in just enough to avoid clipping the edges of the empty lancet window and flaring them again to slow to an elegant touchdown. Twilight Sparkle managed not to hit the outer wall or face-plant onto the marble tiles, but her landing wouldn't have been called graceful even by the most charitable of ponies. Rainbow Dash would have laughed her cutie mark off.

"I trust you remember this spot, Twilight Sparkle." It wasn't really a question.

"Of course." Twilight nodded, straightening up from the awkward position she had dropped into to keep herself from taking a pratfall. "What did you want to show me?"

Luna closed her eyes and took a deep breath through her nose. She didn't say anything for a long while. Twilight shuffled her hooves nervously. Eventually Luna walked to the opposite wall and looked down into the courtyard below. It was only just visible beneath the encroaching trees and bushes. "The Summer Sun Celebration," Luna said quietly. "So many ponies came to see the dawn and were greeted by a nightmare instead."

"I remember," Twilight said, moving to stand beside the princess. "I was there."

Luna gave a throaty chuckle. "No, I'm speaking of the one a thousand years before. The one that happened here."

"Ah."

Luna turned and looked at Twilight as if expecting something more from the little mare and then went on. "The one where a young princess broke the laws of her kingdom and the heavens, and the heart of her sister, because she thought that she knew better how the world should be ordered."

"Uh... wait... you aren't comparing what I did to..."

"'Twas rebellion, Twilight Sparkle. In Canterlot thou didst insist to us the rightness of thine actions in a voice we knew right well. It was kin to that we did fling into the teeth of our sister in this place so long ago: 'I am right!' Those were the last words between us before... before..."

"Luna..." Twilight could see the princess visibly shaking with emotion. She instinctively touched her head to Luna's shoulder in a gesture of comfort.

Luna let the touch continue for a moment but then moved away from the unicorn and began to pace restlessly across the great hall. The whistling of the wind through the broken windows and the twisted trees outside slowly became notes of a mournful tune, and the Princess of the Night began to sing.

"A long thousand years ago, I knew that I was right:
That all my little ponies were wrong to shun my night.
I knew that they would love it, if only they would come
And seek the wonders of darkness, far from the blinding sun.

"But none of them would heed me and from my sight they fled.
It was then that the Nightmare took me and the moon rose full and red.
I battled my own dear sister for naught but a jealousy
But Harmony was her weapon and an end she made of me."

Luna fixed her eyes on Twilight and began to circle her as she continued to sing.

"A long thousand years ago, I knew that I should rule;
With all my heart I knew it, and I was just a fool.
And now you stand before me with righteous anger, bright,
So bright you see not behind you lurks a specter of endless night."

Twilight shook her head in denial and tried to back away from the princess but Luna's circling had taken on a distinctly predatory feel, as if she were a shark closing in on a meal.

"So take heed Twilight Sparkle and tread not the road I chose.
Ahead lies naught but a Nightmare and in your heart she grows."

Closer and closer Luna paced, and as she approached she changed. She grew taller, her coat darkened, and it was Nightmare Moon who loomed above Twilight as she finished her song.

"We two are not so different; take warning from a friend.
We two are not so different, not so different in the end."

"What was that, soldier?" Shining Armor barked at the shivering, wet pony that stood at attention before him.

"Lily pond, sir," Snowdrop repeated, "she dropped me in the big lily pond in the lower terrace garden."

"And why in the name of the sun and moon didn't you high-tail it back to your post instead of coming here?"

"I did, sir! But the suite was empty and I thought I should report to you instead of..."

Shining Armor waved her to silence with a curt gesture and spoke to the two armored pegasi that stood to one side. "Each of you take a squad and begin an aerial search for Twilight Sparkle and Princess Luna. If you find them, send back a messenger and keep following them, but don't approach." Not unless you're good swimmers, he added silently to himself.

The two pegasi saluted smartly and left the room.

Shining Armor turned back to the dripping mare. "You're relieved. Go home and get cleaned up."

"S-sir, I did my best..."

Shining Armor sighed and pressed a hoof against the bridge of his muzzle. "I know. You won't be reprimanded for this. There's not much anypony can do when a princess decides to stick her horn into matters."

Snowdrop was about to comment in agreement when she thought better of it, and she bit back her words. It wouldn't do to forget that the captain was married to one, after all.

Twilight followed the Princess of the Night down the staircase to the salon where the Elements of Harmony had been found. The princess was herself again.

"It's entirely different, Luna!" Twilight insisted. "I'm just an ordinary pony. I'm sure there are plenty of ponies who kick against the traces of Celestia's rule, and nothing much ever comes of it. Or are you saying that the nightmare thing that took you over is still lurking around somewhere and might try for me if I misbehave? That's sounds an awful lot like a filly's bed-time story to me."

Luna stopped abruptly, and Twilight had to quickly step to one side to avoid plowing into the princess from behind. "The nightmare... yes Twilight, Nightmare Moon is just a bed-time story. She doesn't exist. She never existed."

"But... but I saw her..."

"Yes, and you saw her again just now, didn't you?" Luna gave a bitter laugh. "She is a mere costume! She is a metaphor given physical form, an expression of power and cruelty and disregard for anything but my own selfish wishes, and you think it has nothing to do with you!"

"I..."

"You think that you, an ordinary pony, are immune to such folly?" Luna turned away and continued down the stairs. "I will teach you otherwise."

They emerged into the salon, and Luna crossed to the huge stone sculpture that had once supported the Elements of Harmony. Luna swept away the dead leaves and debris that had collected against the base of the pedestal. "Read what it says there," Luna commanded, pointing with a hoof.

Twilight peered at the old runic letters. "Unto the ponies of the Everfree Republic," she read slowly, "We sunder ourselves from this weapon and give it unto your keeping, in token that we intend our nations should ever be at peace. We give our royal pledge that your lands shall be forever free from our magics, for good or ill. - Celestia, Principessa."

"Ordinary ponies, Twilight Sparkle. All they knew was that Celestia had shown weakness... had failed to prevent the terror of eternal night, until there was no remedy but war against her own sister. They lost faith in her and thought they could better rule themselves."

Luna went to a window and gestured out toward the dark forest. "They demanded freedom from Celestia's rule, and in her grief she gave it to them, along with these lands you now know as the Everfree Forest. They did quite well for a dozen decades or so, until their glorious republic tore itself apart under the weight of in-fighting, corruption, and the lust for power. They might have survived all that; other democratic nations have. No, what doomed them was good, honest ponies whose only fault was that they had the unshakable conviction that they were right. Because, of course, when other ponies disagreed, they were not only wrong... they became the enemy."

Luna turned back to gaze at Twilight, and there were unshed tears in her eyes. "I watched it all from the moon and laughed as they died and the wild magic took over their land. The tragedy was that I did not learn from it. You must learn from it, Twilight Sparkle."

"But... if I feel I am right and... Princess Celestia is... is..." Twilight gave up on logic and burst into tears. "She didn't know! I knew! But when I tried to tell her... when I tried to tell all of them that there was something wrong with Cadence, they left me and went to comfort her! The princess left me to be trapped by that evil thing!" Twilight's tears ran down her snarling face as she slammed her hooves against the broken tiles of a ruined castle in the middle of a failed and forgotten nation. "And then she lost! She wasn't strong enough to protect me!" Twilight paused and gasped for air. "I mean Equestria! She wasn't strong enough to protect Equestria."

Luna took Twilight between her forelegs, wrapped her within her wings, and let Twilight sob against her chest until she quieted.

"Oh, Luna," Twilight sniffled, some while later, "what should I do?"

"Ask her pardon and forgive her, Twilight. Forgive her for not being the infallible, immortal sun goddess you assumed her to be. She is but a pony like you or I, and even with the wisdom of so long a life she is not always right."

Twilight thought about Luna's words for a few moments and then sighed. "You're right, I do need to forgive her... because I realize now that it was her I was angry with all along." She looked up at Luna. "But, 'a pony like you or I'? I'll still don't think I can compare myself to either of you."

"How so?" Luna asked in a much lighter tone, "Merely because we are longer lived than you and can drag the celestial spheres around by the short and curlies?"

Twilight gasped. "Luna! That's vulgar! If you're trying to act more like one of the common pony folk, I think that's going a bit far."

Luna was taken aback. "Is it very rude? I heard one of the guards use the phrase, and I thought it sounded rather comical."

Twilight explained it to her.

"Fie! 'Tis most vexatious! Ofttimes the prattle of... oh dear, I'm doing it again, aren't I?"

Shining Armor was not having a good night. He stood on the battlement of Cantelot Castle's gatehouse and surveyed the carnage below. "Sergeant," he said, when he could trust himself to speak in a calm, level voice, "tell me again how five mares and a baby dragon got through an iron portcullis and past your whole platoon."

"Uh... it was the pink one, sir." The poor guard was trying to look anywhere but into the eyes of his disapproving captain. "She had a cannon loaded with... uh... cake."

"Chocolate cake," another guard helpfully amended. "You know the kind they call 'Death by Chocolate'?"

"Except nobody died," a third guard remarked.

"No, but it sure did a number on that portcullis! I never knew it was possible to embed frosting into forged iron," the sergeant explained. "Then the one with the rainbow mane blasted us with some sort of concussion, and by the time we got sorted out, they were already past us and into the castle."

Shining Armor forced himself not to sigh or smack his face with a hoof. "Sergeant, I want you to get your ponies and search the castle until you find those mares, and then I want you to politely ask them to stop rampaging through the halls. Tell them that Twilight is okay and I will come and take them to her as soon as I can." And hope they don't kick my flank when they find out I'm lying, he thought sourly. Oh, Twily, where are you?

Twilight was stalling. She wasn't performing the aerial maneuver; she didn't yet trust her flying skills for that. She was delaying by circling Canterlot and pretending she was admiring the lights.

'Twilight," Luna said as she slid down the air closer to the unicorn's side, "I fear we must descend, now. You cannot put it off any longer."

"I suppose so." Still, Twilight circled. "I remember the day I was afraid she would send me back to magic kindergarten for being tardy. What do you think she will do to me for using black magic and committing treason?"

"You must know she loves you dearly. Otherwise your words would not have hurt her so and your prison would have been very much less pleasant than the Rose Suite. I am sure she will be lenient."

"She loves you, but a thousand years ago..." Twilight began and then cut herself off, cringing.

There was a short silence and then Luna said, simply, "You must face her, Twilight."

"I suppose." Twilight sighed. "Anyway, I think those two flights of pegasi guards are getting fed up with pretending they just happen to be flying in the same direction we are. I don't want my brother to get upset because he thinks I'm messing around with his guardsponies."

"Where is she?" Rainbow Dash demanded of Shining Armor. "If you don't tell us right now, I'm gonna let Pinkie Pie go all random on your sorry flank!"

Shining Armor glanced over to where the pink party pony stood with her fore hooves crossed over her chest and her lower lip stuck out in an adorable pout. Adorable to anyone who didn't know what she was capable of, that is. Shining Armor shuddered and groped for something, anything, he could say to placate the mares surrounding him. Fortunately, his luck chose that moment to do an abrupt about face.

"Here she is, captain!" came a shout from the air above the courtyard, and the flight of guards surrounding Twilight landed not ten yards away.

Twilight's friends all shouted in relief and happiness and rushed to greet her... until they got a good look at her.

Rainbow Dash was the first to react. She pulled up so sharply that Applejack ran full-tilt into her back, and they both crashed to the cobblestones in a heap. Fluttershy suddenly tried to hide not just her face but her whole body underneath her mane, and Rarity fainted on top of her. Pinkie Pie tripped over all of them, flipping over the whole pony pile up, to land right in front of a surprised Twilight Sparkle. Pinkie's pupils shrank to pinpoints, and her mouth dropped open in horror.

"Oh, no!" Pinkie screamed, "Twilight's a vampire! Run for your lives!"