Flames lapped at the walls of the Friendship Castle, fighting against the magic protecting it and those inside.

The world outside shuddered as mountains collapsed, water boiled, the earth heaved and split and fire rained from the smoke-filled sky. The sun was barely visible in the horizon, where it had been stuck for almost a week.

On the opposite side, the moon half-rose, almost split in half, with its jagged, severed piece floating a visible distance above it and slowly disintegrating on chunks of moonstone that would eventually fall onto the surface of Equestria with deadly force, bringing with them the same unstoppable destruction that had laid the Crystal Empire to waste.

All of this, Princess Twilight observed from the tallest tower of her castle. There were no cries of horror from the outside world. Not anymore.

No more lives had been lost when Canterlot—old, beautiful Canterlot—had crumbled like a sand castle. All living creatures left were already in hiding in her home by the time it happened.

All of this, Princess Twilight knew.

And she also knew this was all her fault.

"Princess!"

Twilight shook her head, snapping back to the present. The rain of fire had stopped, and the tremors were gone, leaving the world around them eerily quiet. She looked down to the zebra standing next to her. "Obsidian Scroll," she acknowledged with a tired smile.

"Princess," the zebra sighed. "Thank goodness you finally heard me."

Twilight waited for a moment, then tilted her head. "What, no rhyme?"

Obsidian Scroll rolled her eyes. "I'm not a Shaman and have taken a pony name. For us rhyming is not a game."

Twilight grinned.

Obsidian Scroll's eyes narrowed and she sighed. "It's a habit I'm trying to break. There seems to be no point now."

Twilight's smile faded and she nodded sadly. Her shoulders sagged. Her wings drooped, and her mane stopped waving in ethereal currents, settling around her shoulders. She looked—and felt—really old now.

"Your highness," Obsidian spoke up again. "Gungnir sent a message from Gryphonhome."

"He made it then," Twilight sighed in relief. "I'm glad. I was afraid the fire storms or the sea twisters would have brought him down. What news does he have?"

Obsidian bit her lip. "The capital is no more." She gulped and looked down. "By the time he arrived it had mostly burned down or been washed away by tsunamis. He searched all over, but could not find any living beings. He believes he's the last of his species."

Twilight closed her eyes. "Oh, Gungnir. My dear student, I'm so sorry."

"I had hoped—" Obsidian couldn't finish the sentence.

"Me too," Twilight said, placing a hoof on her assistant's shoulder. "Believe me, Obsidian. I had hoped they had made it to safety."

Obsidian nodded.

"I was there when Gryphonhome was created, you know?" Twilight spoke up, eyes lost in memory. "The first gryphon city created in the spirit of Friendship. Celebrating the renaissance of a millennial culture that had been dragged down by pettiness and despair for so long." She chuckled bitterly. "I never suspected something so beautiful wouldn't make it past its second century."

"Princess!" a shout made them both turn to a pegasus guard, running up to them. "A dragon has been spotted approaching!"

"We haven't seen a dragon in these lands for over a century now!" Obsidian hissed worriedly. "What does it want? Is it hunting for food?" she looked up to her princess.

"Not this dragon," Twilight said sadly, watching it circle overhead outside of the reach of non-magical weapons.

She turned briskly, making both Obsidian and the guard stumble, before her assistant was at her side. "Open the gates," she ordered to the guard, whose eyes widened.

"But—"

"Open the gates," Twilight repeated.

Despite her obvious fear, Obsidian stuck close to her princess as the heavy gates opened, allowing them both to step out onto the charred world outside the castle.

Twilight gave her assistant an encouraging pat on the back with her wing, watching impassive as the dragon flew lower to land, with an earth-shaking impact, in front of them.

The two stared at each other for a moment, and then the dragon spoke.

"Sister."

Obsidian's eyes were wide.

"Spike," Twilight replied, fighting a weak chuckle at her assistant's flabbergasted expression. It would not do to laugh. Not today. Not right now. "It's good to see you."

"Is it?" Spike asked, narrowing his eyes. "Because I just came from what's left of my cave."

"Don't tell me... Luminous?"

Spike looked away, then with obvious effort he opened a claw and revealed the crushed bits of egg in it.

Twilight's world lurched. "All of them?"

Spike didn't answer, simply letting it drop at Twilight's hooves.

"Spike, I'm so sorry, I know you much you loved her an—"

"Spare me," Spike interrupted. "We're family. If you still feel any sort of bond to me—"

"I do!"

"Then don't give me platitudes!" Spike snapped, making Obsidian jump in fear. Spike ignored the young zebra trying to be brave, focusing solely on Twilight. "You have the power to stop this! You can change things!"

Twilight took a step back. "Spike! You don't know what you're asking!" she replied.

"Of course I do!" Spike retorted. "I'm telling you that you have the power to make all of this, better!" He motioned to the world around them. "How many ponies and zebra are left, Twilight? There might be five dragons. Who knows how many gryphons made it. Celestia, Luna, Discord and Cadance are gone. That's our whole remaining family, Twilight! It will take thousands of years for them to reappear—if they even can—and at this rate, there won't be a world for them to come back to!"

Twilight looked away. "I can't."

"You're telling me Starlight Glimmer can adapt a time-traveling spell and you, with more than five hundred years worth of experience—who could have done that before you even met her if you had just felt like it—don't feel it's worth using that spell to change things so we don't end up like this?"

"Spike, changing the timeline is very dangerous, as you well know!"

"Is it going to end up worse than this?"

"It could!"

"How?" Spike snapped. "You know that the reason my mate is dead right now... that there are basically no other living beings around other than your little band of refugees... is just because—"

"Don't you dare say—!"

"It's because you thought your friends were more important than the world!" Spike snapped, eyes blazing. "They told you! The princesses and Discord. They told you what would happen! That you needed to let things—"

"Spike!"

"If you had only—"

"Spike," Twilight said. "Let me go."

Spike blinked through the tears and slowly—painfully—forced open his claw, releasing Twilight. He had been crushing her so hard he had almost broken through her shield. "I-I'm sorry, I—"

"It's alright, Spike."

"Twilight," Spike sighed. "You have to know. This is the only way to save Equestria."

Twilight shook her head.

"Celestia, Luna and Discord were right. It was part of the cycle," Spike insisted. "He's already gone now. You can sense it."

Twilight closed her eyes. The oppressive energy was gone. The world was now at peace and at balance. She knew.

"You know." Spike's voice was resigned.

Twilight looked at Spike. "I made the right choice," she said softly. "Nopony could have known. I wasn't going to allow this... this creature to use the Temple of Harmony."

"He did it anyway," Spike responded. "It only took him 600 years to get to it, but he did it. And he took the rest of the world with him." He snorted, smoke trickling out of his nose. "And for what? For friends long dead."

"Spike, I couldn't have known back then."

"But you know now," Spike replied. "And you have the power to let yourself know the consequences of your choice!" He took a deep breath, visibly calming himself. "We're not talking about a missed test here, Twilight. I'm not telling you to consider this for a random, unimportant thing. Not even for... not even for my wife and hatchlings alone. You can fix this. For the entire world. I loved them too, you know. I loved them and cherish their memories just like you do, but they are mortal."

"Spike..." Twilight sighed, watching him turn his back on her and take off.

"Your highness?" Obsidian finally spoke. "W-was that dragon really your brother?"

Twilight smiled. "Yes." She looked back to the sky, where Spike was already little more than a speck. "Spike is my little brother. We just haven't talked much in the last couple of centuries... and he has given me much to think about."

Twilight took a deep breath. "Obsidian. If... if you had to make a choice... between those dearest to you and the world, who would you choose?"

Obsidian gulped. "I-I think I'd like to say 't-the world', your highness. But... I don't know."

Twilight chuckled. "Of course, I'm sorry to ask that of you now, my dear assistant. When you are not ready yet. That is a question most leaders have to answer in some way or another." She started walking back to the castle. "I have to think."

"C-can you really stop this all from happening?" the young zebra asked, staying in place.

"Maybe," Twilight admitted, stopping, but not looking back.

"My people would live?"

"And the gryphons. And buffalo. And dragons. And billions of others... and yet, the world would change completely... for good or ill." Twilight looked at the sky. "Discord would not have been overwhelmed and dissipated. The moon would not have been cracked into pieces from Luna's struggle and demise. The sun would not be burning the horizon while the rest of the world freezes."

"So why—"

"We would cease to exist as we are now," Twilight interrupted. "You and I might never meet. Gungnir might never be born. The world might suffer another, worse calamity. I might sacrifice my friends for nothing."

Obsidian was trembling. Maybe it was fear for what she was about to ask... nevertheless, she gathered her courage. "And what are the chances of those things happening?"

Twilight did not respond, choosing instead to head back into her castle.

Twilight Sparkle, Princess of Friendship, reached the base of the first temple. It was ancient. Made of dull, gray rock of some sort, carved into harsh edges and towering over her. There were no gates, no obstructions, save a single alicorn.

"Princess Luna?"

The princess smiled. "Well met, Twilight Sparkle."

"What are you doing here? Did you come to help me stop the Arbiter?"

Luna shook her head. "Nay, I came to warn you, Twilight. The Arbiter is not good, but he is not evil either. His sole purpose is to bring balance to Harmony."

Twilight frowned. "But at what cost?" She raised her hoof, motioning past the temple. "My friends were taken."

Luna nodded sadly. "We-I understand. But you must see the bigger picture, Twilight. The power of Harmony resides in them, but also in each Princess, even Cadance, although she brings balance to other forces."

"If he-it, extracts that from them, they'll die."

Luna closed her eyes, but stepped to the side, allowing Twilight to continue. "I pray, Twilight, that you understand this fact does not make me or anypony else happy. I too have suffered this loss."

Twilight marched past her. "I won't lose my friends. There has to be another way."

The next temple was pretty much the same, although the individual waiting was a bit of a surprise.

"Hello, Twilight," Discord said, waving his claw with half-hearted enthusiasm. "Fancy meeting you here."

"Not you too!" Twilight groaned. "Surely the Lord of Chaos can't possibly want Harmony?"

"Well," Discord rubbed the back of his neck. "No. Not really."

"Then will you help me stop him?"

Discord looked away. "I can't. Not now that I've rediscovered friendship... not when I know the price of stopping him would break the hearts of my friends if they ever found out."

Twilight snorted. "And what is that prize?"

"The world."

Twilight shook her head. "I can't accept that, Discord. I've created a spell that will stop the Arbiter forever. If you're not going to help, step out of the way!"

She felt her stomach grow cold when Discord simply moved, allowing her to pass. She didn't say anything else. There was no need. She was too disappointed in him anyway to figure out a way to put it into words.

As she was passing by him, however, he spoke up.

"When I tried to stop this from happening so long ago... it drove me mad."

She turned, but he was already gone.

The next temple was different. The rock felt warmer and the temple didn't seem about to collapse like the previous two.

She knew who would be there.

"My faithful student," Princess Celestia greeted her with a soft smile.

Twilight shook her head. "I thought we were equals now."

Celestia nodded. "We are... this place just brings back memories."

Twilight sat down. "Princess. Are you here as well to advise me against continuing?"

Celestia nodded.

Twilight stomped down on the floor. "Up there, Starlight Glimmer, Rainbow Dash, Fluttershy, Rarity, Pinkie Pie and Applejack are fighting for the future. And we immortals are expected to sit down and watch them without helping?"

Celestia sighed. "There are times when immortals can step in and shape the world, Twilight. We immortals cannot change the world as mortals can. Our place is to move the world forward. To guard it and trust that they can find their own way."

"How can you, the immortal ruler of Canterlot, say that with a straight face?" Twilight snapped, before she caught herself. She blushed under her fur. "I'm sorry for that, but I don't understand!"

"My place as Princess in Canterlot's ruler is different. I offer advice and experience, sometimes I will order ponies to do something mundane. But my role as immortal stops me from creating real change. This is why I let you and your friends deal with Nightmare Moon, Discord and Tirek... before you became the true Princess of Friendship by overcoming Starlight Glimmer and helping her take up the mantle of mortal Element of Magic."

"You are saying that I doomed my friends by befriending her?"

Celestia shook her head. "No. You chose your successor just like Discord, Luna and I did. You are now the immortal Element of Magic, just like Luna is Loyalty and I am Kindness. Like Cadance, Discord represents a different force of balance... but we all had to choose a successor and if the world was too unbalanced, the Arbiter would come to release the mortal elements into the world until they are needed again."

"If this is what I'm supposed to let happen, why aren't any of you trying to stop me?" Twilight asked. "Why let me go through every time, without interrupting me with anything more than words?"

Celestia looked down for a moment, collecting her thoughts before she moved out of the way. "I can't speak for Discord or Luna. But a part of me wants you to succeed. I will always have faith in you my st—my sister," Celestia smiled at Twilight's surprised face. "I know you will make the right choice... whichever it will be."

Twilight gulped. "T-thank you, Pr—Celestia."

She slowly made her way up the large set of stairs until she could see it. The Temple of Harmony. It was made of crystal and rainbows and clouds and stone floating in a sea of stars. It was huge, especially compared to the places where she had talked to the other princesses and Discord.

At last she would be able to join her friends and face the Arbiter.

She stepped onto the crystal courtyard and stared, open-mouthed at the pony waiting for her.

"You can't be real," she whispered. "Not you. You can't be here to tell me to stop."

Princess Twilight Sparkle looked imposing in her regalia. She had grown to Celestia's stature, and like Luna and her sister, had a mane that waved in unseen winds. And she did not look happy.

"I am here," she said, "To tell you the consequences of your actions today."

Twilight grimaced. "I thought we immortals were not allowed to interfere."

Her other self rolled her eyes. "Don't even try. You will hear me out before you walk into that temple."

"Fine," Twilight said, sitting down and eyeing her future self with a bit of resentment. "But you know what my answer is."

"No, I don't," future Twilight replied. "Because I did not appear before myself the last time this happened. I am here to change the past not warn you and waste both of our time.

"If you go past those columns, you will fight, and you will win. The Arbiter will be gone for six hundred years."

"Then what is the problem?" Twilight asked. "I want to save my student and my friends."

"I know, but you must understand what will happen if you do," future Twilight retorted, looking down at herself. "If you fight, the Arbiter will grow unbalanced. His power unchecked. Just like he balances the world's harmony, he is balanced in himself. Depriving him of his duty will break his inner balance. Power will accumulate for 600 years, and when he comes next, unannounced, that power will force balance upon itself through the world and the forces that hold it together.

"The first to perish will be the immortals that hold the balance of nature. Celestia will disappear at dawn, leaving the sun to scorch half the world. Luna will lose control of gravity and the moon will split in half when she can't hold her grasp on it. Discord will overfeed on the chaos and rather than take the world with him, he'll force himself to cease to exist to spare every being on the planet.

"Cadance will fade away as love disappears from the world and despair settles in. Thus, the first to die will be the Changelings."

Twilight's eyes widened as she heard herself explain what would happen. "But—"

"The lack of these unifying forces, along with the Arbiter's loss of control, will crack the center of our world like an eggshell. Through the fissures the world at large will be affected. Earthquakes will shake the continents. Tsunamis will drown whole landmasses. Mountains will collapse. The survivors—all two hundred of them—will gather within our castle, which is protected by the strongest magics, to weather it out.

"By the time it's all over, there won't be water that is not toxic to drink. No patch of arable land. No wildlife. No forests.

"Through it all, you will remain convinced that you did the right thing, until you finally step out of your castle. Feel the charred, dead land under your hooves and breathe in unfiltered, burnt air.

"In the following years, your student will take his life in despair. Your assistant will see the last of her kind pass away and will spiral into a self-destructive stupor. Spike will fall asleep with no intention of ever waking up.

"These are the consequences of your actions today, Twilight, should you step through."

Twilight Sparkle stared in horror at her future self. "But... but I want to save my-our friends! How can that be wrong?"

"There's nothing wrong with wanting them to live, Twilight," her future self responded. "But you are not their caretaker anymore. They have to fight their own fight. And us immortals can only bear witness to the mortal's glory when the time comes and carry it with us into eternity."

"But what happens if I don't go in there? Won't they die?"

"Probably," her future-self replied. "Things were not good when I went in."

An explosion shook the temple and both princesses turned to look at the structure.

"What should I do, then?" Twilight finally asked.

The princess from the future slowly started to fade away. "Do what your heart tells you to do, Twilight," she said. "But be fully aware of the consequences of what your choice will mean."

And she was gone, leaving Twilight sitting alone in the patio in front of the Temple.

There was nopony else to stop her. No more words of advice, or warnings. The choice was hers alone and she knew exactly what would happen now if she did interfere.

A heartbeat passed.

Twilight made her decision.