Princess Celestia lay on the divan in her private study, leafing through a recent scientific journal.
"Celestia..." called a distant voice.
She looked up. "Who's there?"
"Celestia!" called the voice again, now much louder and closer.
She sparked up her horn and cast a detection spell. She detected no one in her tower but the standard detail of guards and servants.
"Whoever you are, show yourself. I am in no mood for games," she said, sternly.
A burst of light put an elderly stallion in the center of her floor.
"Celestia!" he bellowed.
Celestia gasped. "Starswirl? Starswirl the Bearded?"
"Yes. It is I," Starswirl the Bearded said, approaching her.
"This cannot be. Starswirl disappeared well over a thousand years ago." She stood up and loomed imposingly over him, her horn afire. "Who are you, really?"
"Celestia, do you remember what I said to you when you botched your transfiguration midterm? Your greatest weakness is that you overthink..."
"...and under-analyze. I still don't understand what you meant by that," she said. Her horn stopped glowing. "Starswirl, what happened to you?"
"There is no time to explain right now. I have come to deliver an urgent warning. I have peered through the veil of time and space and gazed upon the potentialities of existence. I have discovered a crucial nexus point in pony history. Or, rather, your future."
"What do you mean?"
"Everything comes down to one decision. At some point in your life, you will meet a boy with cutie marks depicting the two of you in the throes of passion."
"I have met this boy! Please, tell me. What does it mean? What am I supposed to do about him?"
"Listen carefully, Celestia..."
Radish patrolled an empty corridor of the palace's administration building. He stopped to examine the inspection date on a fire extinguisher. Princess Luna appeared behind him in a burst of teleportation magic.
"Radish!"
"Ma'am!" Radish gasped. "What do you need?"
"I wish to share something most comedic with you! In light of the defeat of the mischievous Discord, and the prankful joys of Nightmare Night, I have played a delightful trick upon Celestia!"
"Oh, really?"
"Truly! I entered a dream of hers, taking the form of our old mentor, Starswirl the Bearded. In this guise, I delivered a mock prophecy regarding your cutie marks!"
"What? What did you say?"
"I told her that if she does not sleep with you before the next summer equinox..." Luna started to crack up. "...all her hair will fall out!"
Radish cringed.
"What?" asked Luna. "Is that not hilarious?"
"Ma'am... I'm not so sure she'd see the humor in that."
"No?"
"No," said Celestia, icily. Radish and Luna turned to see her scowling.
"Now, sister," said Luna, cowering away, "it was merely a jest."
Celestia pulled a pair of shears from behind her and snipped at the air. "You want to talk prophecies, Luna? How about we predict how long it will take for your mane to grow back?"
Luna cowered behind Radish. "Protect me, my Champion," she whimpered.
"Uh..."
"Stand aside, lieutenant. This is between sisters."
Luna teleported away. Celestia teleported after her. Radish stood in silence for a moment, then returned to staring at the fire extinguisher.