1000 Years Ago

Ponyville Plain

The land that would later host the town of Ponyville was, during this moment, unrecognizable. The bodies of countless fallen soldiers lay amongst broken weapons, torn ground, and scattered trees. The sun hung low in the sky, and the clouds darkened the air.

Among the remains of this carnage stood two figures. One was an alicorn, white in color, wearing armor of gold. The second was also a pony, but much more broad and warrior-like. This one had a coat of gray and a mane of tan, and he wore armor of steel. His face was worn, his eyes bright blue.

"So it has ended." the second pony said. "The Griffons have been routed. My army is capturing what dared to remain here."

"It seems so." said the Alicorn, Celestia, Ruler of Equestria and Princess of the Sun, replied. "But now, we must depart from this place. My forces yearn for home and their families, Saladin."

"As do my own." Saladin replied. "However, there is still the terms of our agreement."

"Indeed." Celestia sighed as the two departed from the grisly scene. "However, I still do not understand your terms to the fullest extent of their meaning."

"By the time the Fourth Alicorn comes of age, whoever it may be, the world will be ready for our return." Saladin replied. "Cydonia is tired, and wishes for rest from the horrors of war."

"I understand." Celestia said as they entered their camp, proceeding to the command tent. A Cydonian Scribe appeared, bearing a scroll. As Saladin unfurled it, it revealed a document that would shape history.

The Treaty of Agamid.

Celestia signed her name to the bottom, and so did Saladin. One clause in particular caused Celestia some concern.

"When the Fourth Alicorn comes of age, they will be the betrothed of our firstborn Prince or Princess."

As Celestia rolled the scroll up, she presented it to Saladin.

"May your nation prosper, forevermore." Saladin said.

"And may your own lands be given the same blessing." Celestia replied. "I will miss you, old friend."

"Indeed." Saladin replied. "My army and I shall be gone by dawn tomorrow."

As Celestia watched him depart the tent, she nodded stalwartly and returned to her own camp, to begin the march home to Canterlot.

=====

Celestia woke with a start, throwing off the blankets that covered her with a yelp, then she realized what she had seen was but a dream. As she watched the moon grace the night sky, she remembered why it was so vivid, so...laden with emotion.

Today was the day Celestia had been dreading all her life. The news of the coronation of Twilight Sparkle, her faithful student and now Princess of Magic, had spread all over the world in the six months since Lord Tirek's downfall.

And they most likely had already reached Cydonia by now. Celestia knew not how the warrior nation had changed over the centuries, as her last visit was over 1000 years ago. However, the daunting realization still hit her, full force.

Today, the Cydonians would come to fulfill the treaty she had once signed, and claim the fourth Alicorn.

Celestia took a scroll of parchment and began to write, hot tears beginning to fall from her eyes.

====

Twilight Sparkle awoke to Spike poking her in the head with a scroll. With a grumble, she pushed herself up and looked at the dragon with an air of annoyance.

"Letter." Spike said. "It's from Celestia."

"It's four in the morning." Twilight moaned. "What could Celestia want at this hour?"

"I don't know, I just thought you should see it." Spike said. As Twilight read the scroll, she found it was shorter than usual.

Dearest Twilight Sparkle,

Retrieve the Elements of Harmony and come to my office in Canterlot immediately. There is something urgent I must discuss with you.

No matter what happens to you, know what I did was for the best, and I had hoped this would never happen to you.

Celestia.

Twilight rolled up the scroll and sighed, sliding out of bed and heading to the bathroom to freshen up.

"Spike?" she called, over her shoulder. "Get the girls. We're going to Canterlot."

"Why?" Spike asked. "What's Celestia need us for?"

"She didn't say." Twilight said, turning on the sink and splashing her face with water. "Let's get moving."

=====

As Twilight woke each of her friends one by one, she grew more and more curious each time she reread the letter from Celestia as they headed to Ponyville Plaza, where there would be nothing to disrupt their journey by teleportation.

"What do you think it means?" Twilight asked no one in particular, out loud.

"I have no clue." Rarity said. "It seems mysterious, though. Why would she put these lines at the bottom here?"

"Can't say for sure." Twilight replied. "I can tell it's important though."

"Whatever it is," Rainbow moaned. "I wish it could've waited until morning."

"It'll be fine, Rainbow." Applejack said as Twilight prepared to teleport them all to Canterlot. "Whatever happens, we'll be with you, Twilight. We'll make sure of it."

=====

As the Elements appeared in Celestia's office, Twilight saw a shocking sight as their vision returned, as the bright light that blinded them faded away.

Celestia was crying into her pillow, tears streaking down her muzzle and into the sheets.

"Celestia?" Twilight asked, panicked at the sight of viewing her mentor so distressed. "What's wrong?"

"It's complicated, Twilight." Celestia said, wiping her eyes. "I suppose your friends will want to hear what I have to say."

She took a deep breath, and Twilight immediately sensed inside her mind something wasn't wrong, something was very wrong.

"Have you heard of the nation of Cydonia?" Celestia asked.

"I've heard mentions to it in a couple of ancient texts, from around the first Hearth's Warming celebration." Twilight replied. "Weren't they some of the finest warriors the world ever knew?"

"Yes, they certainly were skilled, and feared." Celestia said. "During the formation of Equestria, they aided us in defending our land from countless threats. The Dragons, Griffons, and even the Minotaurs were unable to best them in warfare. At the Battle of Agamid, a merged Cydonian and Equestrian army forced a combined Griffon army three times our size to surrender after three hours of combat."

"Wow." Rainbow said, floored. "They sound cool."

"That is not the word I would use, Rainbow Dash, to describe them in this case." Celestia replied before softening her tone of voice. "After that battle, I signed a treaty with their ruler, King Saladin. In exchange for their service to us, I promised them something I now deeply regret, even after 1000 years."

"What did you promise?" the Elements asked.

"I promised the Cydonians that somepony would be betrothed to their firstborn Prince or Princess." Celestia said. "Today they are coming to collect ."

"Who is it?" Rarity asked.

Celestia sighed, wiped a tear away, and muttered something so quiet, it was inaudible.

"I'm sorry?" Twilight asked. "I couldn't hear you."

Celestia mustered herself again, and looked at Twilight with regret and remorse clear in her eyes.

"I promised them the fourth Alicorn once they came of age and were eligible for marriage by the Cydonian laws. That...is you, Twilight."

There was silence as the jaws of everypony in the room hit the floor. Twilight took a deep breath and opened her mouth.

====

"WHAT!?"

The tremendous shout of six ponies and a dragon echoed through the whole of Canterlot, just as the moon lowered in the sky. Celestia barely had time to register that her protege had used the Royal Canterlot Voice inadvertently. Then, the Elements began to speak at once, all together, with panic in their voices.

"That's impossible!"

"Twi can't just leave Ponyville!"

"But...why?"

"Can't you stop it?"

"Who's going to take care of the Castle?"

"What about Spike?"

Celestia waited for the pandemonium to calm, before she spoke, raising her hoof to quiet the Element.

"First, Rainbow, it is possible. I made this promise a lifetime ago, and I intend to keep it. I am an alicorn of my word. Second, Applejack, though I regret to say it, she has to leave once the Cydonians arrive. Third, Rarity, it is not uncommon for marriages to be in diplomatic treaties. Fourth, Pinkie, I cannot stop it. I have seen the Cydonians when they are angered, and it is something I do not want to witness again. Fifth, Fluttershy, I will maintain her Castle. Finally, Twilight, I will make sure Spike can come, along with whatever you wish. The Elements will also be able to visit her as much as possible."

The Elements of Harmony were silent as they turned to the Element of Magic. Twilight and Spike slowly walked forward.

"When...will they arrive?" Twilight asked, a cold feeling on her neck.

"Today." Celestia said. "I know not what has changed, but they will arrive with their warfleet, as usual."

The Elements tried to protest again, but Celestia silenced them with a glare so harsh, even Rainbow gave a quiet moan similar to Fluttershy when she was in a scary situation.

"Twilight, please understand this is for the best. The Cydonians may be warriors, but they know hospitality like no other. I am not asking you to agree with this whole arrangement, but I am asking you...to trust me."

====
Near the coast of Equestria, around Canterlot

Cydonian Flagship "Saladin's Pride"

"Young Lord, we are...Lord Mathias!"

A unicorn of Twilight's age, with a tan coat, an unkept black mane, and blue eyes jumped slightly at the use of his given name, and he turned from the mast to the soldier who addressed him. Mathias nodded, acknowledging the armored stallion who had spoken.

"We are nearing the coast. Princess Celestia is expecting us."

"Steady as she goes." Mathias replied. "Let's not make a scene."

"As you command."

The soldier saluted, and left for the bridge. Mathias stood up and headed for the bow, leaning on the rail.

"So, we're almost there." said Mathias's Pegasus guard, Ceris, who flew up next to his liege Lord.

"Indeed." Mathias said. "I can't believe it'd be so soon. My ancestors signed that treaty over 1000 years ago."

"It still holds true." Ceris said. "Let's just see how they greet us, and we'll go from there."

"I hope the Fourth Alicorn shares my feelings about this whole thing." Mathias grunted. "I never agreed to this."

"You must remember that the Treaty of Agamid was signed by your ancestor, and you are the firstborn at this time ." Ceris replied. "Just take it one day at a time, and you'll be fine. Go with the flow."

Mathias groaned as the city of Canterlot came into view off the starboard side of the flagship.

Author's Note

Yep, it's back from the dead. Apart from Over the Wall, this was my first original concept that I developed into a story.

And now, it's staying for good. No more deletions, and that's a promise!

Next time - The reluctant bride meets the reluctant groom.
EDIT 3/26/2022 - Added revisions to the chapter.