Will the last pony to leave...
...please turn out the lights.
Celestia sighed, once, deeply, watching the luminescent backwash from the last spaceship fade. It hung in the thin air, signaling the time had come. She took one last long look at the fallen palace surrounding her, mentally bidding the crumbling ruins she'd lived in for last several centuries farewell and gathering her strength, concentrating on the last thing she needed to do.
"Um, excuse me?"
She jumped at the unexpected interruption, spinning to find a uniformed delivery pony looking through an unexpected teleportal.
"Sorry, do I have the right address? Only, I was told this is where the party was..."
"Um, I-" She started to reply, confused, but was cut off by a familiar voice.
"That's right, start setting up. The boss will be along in a minute."
She turned towards the newcomer, and was surprised by a hug.
"Celestia! It's so good to see you!"
"Twilight?" She stepped back, glad to see her favorite student but bewildered by what was happening. "Why are you here? What's going on?" She stared around in confusion as delivery ponies poured in, carrying decorations and furnishings. Just like that, tables covered with food, games, party favors and other treats appeared. Suddenly, the boss arrived and kicked the chaos into overdrive.
"ALL RIGHT, PARTY PONIES!" A pink blur zipped through the portal, and took over the setup with a burst of confetti and balloons. "Let's get this party started!" Pinkie paused for a second to hug Celestia, her cybernetic body buzzing with the whirr and hum of overloaded servos. "Sorry Princess, I wanted it to be a proper surprise, but this is the best I could do. Give me a minute to set things up; the rest of the guests should be here shortly." She darted off with un-pony quickness, her enhanced neural network allowing her to coordinate the setup a very nearly the speed of light.
"Sister!" Celestia was glomped again.
"Luna! I'd almost given up waiting for you!"
"I'm sorry." Luna looked down, genuine contrition playing across her face. "I wanted to come earlier, but Pinkie made me promise. She wanted a surprise-"
"But it didn't work. I know, she told me." Celestia laughed, suddenly feeling a lot better. Maybe today wouldn't be quite as hard as she expected. "So," She turned to Twilight. "Who else is coming?"
"I'm not really sure, besides Spike." Her student twitched a wing absentmindedly. "I've been immersed in lighting up a new solar transfer node with him, and I didn't really have time to read the guest list. I don't think it will be a big party, but with Pinkie you never know. Oh look, here he comes!" She pointed to where a stream of flame descended. It fell at dizzying speed, the tortured air literally burning around it. Despite that, it touched down as lightly as a feather and uncurled into the familiar shape of a colossal dragon, emerald wings and scales barely warm.
"Spike!" Twilight rushed forward. "It's so good to see you! How did the node start-up go on your end? You don't have linkshock, do you?"
"Sheesh Twilight, I'm fine. If you'd waited just a second longer, I could have warped across and come with you instead of taking the long way." The green wyrm preened for a second, rubbing stardust and soot off his wings and scales before shrinking himself to a more manageable size. "I'm glad to see you, too." He hugged Twilight before slithering over to join the group and exchange greetings. "So, is this it?"
"Nope!" The pink cyborg re-joined them. "Hi, Luna, Spike, Twilight! Just a few more guests!" She turned back to the portal, and waved the last of the hired hooves away. It shut with the snap and crackle of torn space resealing, leaving the five of them standing silently.
"So who else-" Celestia's words were cut off as a ripple appeared in the air in front of them. With a gut-wrenching twist reality itself unfolded, revealing the forms of a draconequus and a butter-yellow pegasus.
"Fluttershy!" Twilight exclaimed, leaping forward to hug her friend.
"Oh, sure. SHE gets all the-" Discord's bitter soliloquy was cut off by a gentle embrace from Celestia.
"Hush," She said. "We are your friends, too."
"Oh, well. It's good to see you too, Celly."
The princess smiled at that.
"We should really talk more.We do go way back." She said softly.
"Oh, careful! You're getting sentiment on me." He brushed a speck off his shoulder, and smiled to take the sting out of his words. "You're welcome to visit us. Flutters would love to have you, and we have plenty of room. What do you say, Sunny?"
"I think...I'd like that. I haven't really made any plans. This whole thing..." She gestured upwards, taking in the sun and the sky, "hasn't left me much for room for thought." She looked down, slightly abashed. "I'll be the first to admit that i may not have been thinking very clearly."
"Well, enough thinking!" Discord said, with a smirk. "For now, enjoy yourself. Oh, and here are the last guests!"
As he finished, a blinding wave of pink light washed over the group. Twilight coughed something that sounded like 'Showoff' as two new ponies appeared. One was a pink alicorn with an ethereal mane that glowed the colors of sunset, the other was a sky-blue pegasus filly, wide eyed and clearly intimidated by the company she found herself in.
"And that, Perseid, is how to teleport long distances," Cadance said, wrapping up the lecture. She looked up, smiling at the group. "Hello, everyone! It's so good to see you! This is my student, Perseid Lumin! Are we late?" Luna snickered at her worried expression, but Pinkie was quick to re-assure her.
"Nope, you're right on time! Now, let's PARTY!"
And then there was merriment.
Much later, when the games had been played, and the food was mostly eaten, and they had even sung a song or two, they were all sitting in a circle swapping stories. Celestia took one last bite of cake, and decided it was time. She set her plate down and let Cadence finish her tale, an anecdote about her first husband, Shining Armor. Everyone laughed except for Perseid, who seemed slightly shocked by the idea that her teacher had once been married. They all fell silent as Celestia tapped her fork against the edge of her plate.
"Please come with me." She stood, and they followed quietly. She meandered a while, letting bittersweet feelings carry her to and fro through the ruined marble palace, saying goodbye to many memories before stepping onto a terrace under the open sky. Her friends formed a semicircle around her and she turned to look at them.
"I'm old." She smiled a little. "You few immortals understand just how true that is. But once again, I've realized I still have much to learn." She looked up to the sky. "I've led ponies for many years. I've watched empires rise and mountains crumble. I invested my heart and soul in everything I did. And I have to confess, although I've long seen this day coming, I dreaded it from the second I realized it would happen." She turned, and waved a wing at the surrounding landscape.
"You see here, a dead world. Although I may be able to raise and lower the sun, not even I can stop the progression of nature. Not one pony outside of us walks here. Very few could even survive. You," She pointed to Twilight, "have done so much to give me hope. You gave my little ponies the stars. They have come so very far. You all have taught them so much. And I confess, it made me slightly bitter. I saw my era was ending, and thought, that as ponies became less reliant on me I would be loved less." A sparkling tear slid down her white cheek.
"Oh, how wrong I was. Thank you all. Thank you for taking the time to help me feel better. To spend some time with me, to make me the center of attention and show me that you still care. This is something I've taught, but also something I've learned and re-learned: time spent with friends is time well spent. And you can always find strength to face the future, if you have friends at your side." She began gathering power around her horn. "My heart is lighter than it's been in years. So, with a smile...for one, final time, good night."
And with a flash a gleam and a twinkle, she put out the sun.
"...Well, at least this was better than our last end of the world party."
"You're never going to let me live that down, are you?"
"Nope!"
But the party continued, under the stars.