As the world outside the cave grew darker still, five generations of dragons, plus one alicorn, solemnly huddled around the purple-scaled behemoth in the center. He didn't have much time remaining.
The recumbent dragon gazed at the lavender-coated alicorn before him, and, in an disconcertingly hushed voice for such a gargantuan creature, whispered to her and her alone.
"...Guess this is it, huh?"
"I guess so," the alicorn replied.
"...How much do you wanna bet Pinkie's planned a 'dragon-sized' welcome party for me?"
In spite of herself, the alicorn chuckled. "I think that's pretty much a given, Spike."
There was a brief silence.
Then, Spike took on a far more concerned tone. "Twilight, I'm sorry I can't—"
"Spike, don't worry," Twilight reassured her longtime friend. "You can go. I... I'll be alright. I promise."
"...Y-You sure?"
She nodded. "Cross my heart, hope to fly, stick a cupcake in my eye."
Oh dear something tells me a thousand years has been passed and Spike hits his limit of his life span that's so sad and pretty much he was the last creature that Twilight knows 😢
Makes me think of the Fic which explains Alicorn immortality as "Infinite Respawn" where Alicorns can die but come back in a new healthy body in just a few seconds, but with the option to spend time in the afterlife visitng the dead before respawning again. I imagine Twilight telling a small group of ponies she can do this so she can take "vacations" in the after life every once in a while to see her friends after they die