Twilight Velvet was giving Princess Celestia a pained expression.
"You mean to say, my daughter will be... will be like you."
Celestia nodded.
"Yes. She will ascend to an alicorn, a status that will immediately elevate her to minor princesshood."
"But why her?"
"Why not her?"
Twilight Velvet looked away, her gaze finding its way to the tea set on the table between them.
"I suppose," Twilight said, "I always knew this day might come. Something like it, anyway. She did so much with you. . . Excuse me."
She turned her head away to daub at her eyes.
Celestia murmured supportively, looking none too proud nor sad - always regal.
"It's just," Twilight resumed, "It's all so sudden, too much to take in all at once. First Shining, now this. . . Couldn't you have given us more warning? Given me more warning?"
"I am sorry, my little pony, even I could not have been certain. It might have been a year ago, perhaps five years from now. You have suspected such a day might come, is it such a shock?"
"But a warning, Your Highness! Something, anything! Not showing up on my doorstep and announcing that seeing her at the wedding was the last time she would be like the foal I gave birth to!"
Twilight Velvet took a breath or two before she recovered herself. Celestia gave her the time.
"You. . . You're certain, Your Highness? It will happen?"
"In a matter of days, possibly sooner. I have arranged for Star Swirl's tome to come into her possession by now, it is only a matter of when."
Twilight Velvet shakily took another ship of her tea.
It was then that Celestia saw it. Every pony has those moments in life where a sequence of events - events that one cannot know the full detail of - comes into perfect clarity. Something that happened, or something that is about to happen, or, sometimes, something that is happening somewhere else. As a magical being some four thousand years old, Celestia was familiar with the experience, but treasured each one.
Celestia was twelve years ago, watching the mare before her with her daughter, on the morning before her magic exam. She saw the years leading to that moment, the foal Twilight Sparkle becoming obsessed with magic, to the exclusion of all else. She saw the mare watching it happen, spending her days networking, connecting with ponies of affluence, to prepare a place for her daughter; saw the mare expressing her love for the foal everywhere but to the individual it mattered most.
Celestia saw the explosion of magic that had made Sparkle her student. Followed her determination to excel, to pursue magic, to, she had to admit, the unfortunate exclusion of friendship. But here, in this vision, there was a difference. In this picture, Celestia saw more family. There were weekend evenings spent at dinner conversations in place of all-night study session; after each test, the young Twilight Sparkle would rush home to her parents and her brother, expressing her doubts about her performance, or gushing on about her excitement; even skipping a lecture here or there to go on vacation adventures in Trottingham or Appleloosa.
There was darkness, too. Nightmare Moon returned for days, not hours. Discord had a reign, and Equestria was blessed with one fewer princess-to-be. But there was always light, always harmony at the end.
The vision came all at once, every moment fully realized and interconnected, the point of divergence shining brightly, to which all the rest was connected. It was a sentence. A single phrase that summarized the mare's love for her daughter, that the daughter never heard. Such a small thing.
As they are about to step into the lecture hall, there are six words that Twilight Velvet says this time: 'No matter what, I love you.'
Then the vision was gone, leaving only its memory, and Celestial was back in the room she had not left, with an aggrieved mother.
"She will still love you, Twilight Velvet. And you will still love her. Nothing can change that. This I promise."
Twilight Velvet trusted her.