Author's Note
You know what feels incomplete? This story. But not in the usual way. This is JUST THE END.
I'm not taking it down, but don't expect it to quite work.
White and Blue
"Twilight, who is this other friend of yours?"
Twilight looked across the cloud to where the princess was gesturing - the celebrating group and the three Wonderbolts Rainbow Dash had just saved. There was only one pony she could have meant. "That's Vinyl Scratch. I believe I've mentioned him in my letters."
"'Him?'" Celestia perked an eyebrow in… not quite confusion, but perhaps concern?
Twilight explained, wondering if she had somehow never heard of this in her many years. "Yes, he was a stellar conjunction baby. One of the many possible side effects of that can be maturing to appear to be the opposite sex. He's a fully functional stallion, though."
Twilight realized what she'd just said. She couldn't see a way to defuse that without lying, so she just hoped Celestia would drop it.
She didn't. "How did you meet?"
"Well, he was the deejay at the summer sun celebration afternoon-to-evening party. Which was in the library. And I was really tired, so I just sat in his seat when he wasn't in it, and when he came back we got to talking about electronics and music and mathematics."
Celestia nodded, and her frown deepened. "Then this is the pony whose house was recently destroyed and so moved in with you?"
Twilight swallowed, wondering what was going wrong. "Yes."
"Has he made any untoward advances upon you, taking advantage of the proximity?"
Twilight carefully considered the question and answered, "No, none at all."
Celestia relaxed. "Oh, good. How does this affect your friendship with the girls?"
"Not at all! We all get along fine. If anything, he helps, acting as a lightning rod for my more intellectual side. We… my friends and I are very complementary - our friendship is based on our differences. With Vinyl, it's very much based around the things that are the same - we're kindred spirits. Also, he's friends with each of them for different reasons. Not as close friends as they are with me, but enough that his presence feels organic to all of us."
Celestia carefully asked, "Do you know his parents? He seems familiar."
"No. He did mention them at one point… well, when we all got affected by poison joke, he was basically turned into my brother."
Celestia observed, "Yes, there is a resemblance."
"Long story short, being beefy was kind of a parental issue, and I'm wracking my brains to think… father was Deep Gouge? He was a royal guard who was rather disappointed by how Vinyl turned out. He passed on a few years ago."
Celestia nodded sharply. "Twilight, are you familiar with the expression 'familiarity breeds'?"
After an empty moment, Twilight tried to finish it, "… 'contempt'?"
"No; the expression I'm referring to is a play in words on that expression, though. In short, I am concerned that if you live with him, sooner or later you might develop an attraction and romantic feelings simply from sheer availability, which is not the best criterion."
"Oh, there's no worry of that."
Celestia began to smile, then it turned suspicious. "How can you be so confident? Is he only interested in stallions, or you in mares?"
"No. Er. I hadn't quite gotten around to mentioning this in my letters, but now that you're asking directly, it's that we were already romantically involved before he moved in. Into the basement, where I do not sleep."
Celestia stared at Vinyl for literally a minute, interrupted only by a guard approaching to say that her chariot was ready; she barely nodded an acknowledgement.
Twilight spent that minute swallowing over and over, wondering if the princess felt that she had a right to know about this in a more timely fashion, or if she was upset about her living with him without having married.
Suddenly, Celestia asked, "Do your parents know?"
"We have arranged to meet just before the gala."
"Ah yes, the unexpected seventh ticket?" To this, Twilight nodded. Celestia stared for another ten seconds, then observed, "Your brother was also born during a stellar conjunction, wasn't he?"
"Yes, but not the same one. Vinyl suffered two side-effects – looking like a mare was only the second. The first was spontaneous petrification the first time he fell asleep after being born. He only came free of that fifteen years later, during the next conjunction. So, he's technically forty."
Celestia nodded. "How common is it to have two distinct side effects, or none?"
Twilight considered. "None of the books I read on it even covered either case, so I'd guess it's pretty rare. But it happens - my brother didn't have any."
Celestia beckoned to Vinyl, who noticed, approached, and took off his goggles. Celestia asked him, "Where were you when you stopped being petrified?"
Vinyl raised an eyebrow but immediately answered, "Canterlot General." Celestia nodded.
Twilight gasped. "Oh my. And the day had to be the same because of the conjunction…"
Vinyl shrugged. "And?"
Twilight said, "We might need to to a genetic test to see if you were switched with my brother when you un-froze. I can see it now - the petrified baby who's been sitting there for fifteen years un-petrifies, and now has the same colors as the newborn. The nurse comes in, grabs the crying baby and takes him to his mother…"
Vinyl blinked. "Oh."
"And the petrification is associated with firmer spells. And my brother's the shield specialist! Do you have firm spells?"
Vinyl blinked. "No."
And with that, they were silent.
Celestia wondered…
Should she tell them how, upon seeing the son of Deep Gouge and Wave Crest be petrified by the conjunction, had long thought of what a waste it would be for such a magical potential to be raised in the household of a rigid-minded guard and an eccentric artist; how a great talent in shields or magical construction might emerge if this potential were to be nurtured in a more intellectual household; and given the upcoming trials the nation faced, how important that might be; how she had visited Twilight Velvet and altered the coat and mane of her unborn son from pale blue and darker grayish blue to match the colors of this petrified child, and how she had switched them, knowing that any child of Night Light and Twilight Velvet would have enough of an artistic bent to fit in well with Wave Crest and their older/younger daughter Octavia, already a violin prodigy?
What would revealing it achieve? Yet Twilight was on the path to princesshood. She should know these things, much as Celestia would have benefitted from knowing that which princess Platinum had hidden about her own origins.
Vinyl was thinking back to last night…
His sister had come down to his basement room after Spike was in bed. His sister had not said a word as she crawled into his cot and lay on top of him. He'd put his forelegs around his sister and kissed deeply. He and his sister had writhed around, enjoying the contact, restrained as they'd been all day from any public affection, from any lewd displays that they both wished for. He had lifted his sister up and warmed her up with his hooves, and she had slipped down off the bed and sucked on her brother's penis…
Vinyl thought further back, to the night of the sleepover, when Applejack had dared him to prove that he was actually a guy and not just putting them on, and he'd shown them his tiny penis. And how Twilight defended him, saying that it wasn't uncommon; how her father was that small (though not her 'brother'), and there were plenty of mares out there with similarly diminutive parts a perfect match for it. Such as her. Yes, it seemed ironic, that a big hint that they were related ended up being the moment Vinyl realized she was really into him, while being completely missed for its more important clue.
… returning to the previous night, he thought back to how his sister had come back up to kiss him. He had picked his sister up in his forelegs, letting her hind legs on the cot guide her down. His sister had lowered herself onto him, and he had picked his sister up and carried her around on two legs, bringing her to the electrical table while thrusting into her. He'd hooked up the padded clamps to himself and his sister and run the current between them. And his sister had wailed in ecstasy, guided by the sexual wisdom of the ancients and the latest modern techniques into a cascading series of orgasms - for it turned out you could learn how to fuck from a book, so long as you also got to practice. And then she had eagerly accepted the seed of her brother, only vanishing the parts that leaked out. And once they'd had their post-coital snuggle, his sister had snuck back up to her room shared with her…
… her actual brother, Spike the dragon. No, Vinyl was not Twilight's brother, genetics aside. They'd just have to keep being careful and have children by other means.
Twilight thought ahead…
Shining Armor there to impregnate her with the grandchild of Deep Gouge and Wave Crest. She knew the techniques needed for a very high union, the insertion of his large peg into her small hole. Vinyl would get her warmed up, loosened, ready. Shining would watch and become aroused. Then when Shining was at half mast rising, Vinyl would back out of her and she'd flip over and present herself. Shining would line up and push in.
Maybe the first time it wouldn't work, and they'd have to come back again? No. Obviously, she'd just take his glorious penis in her mouth, and suck him dry, and then she'd spit into something and they'd put it in from there. Or somepony, not something. Hmm. Would she snowball into Shining, or Vinyl? Or maybe there's another mare there, to be fair to Vinyl. Hmm, who'd be good? Rarity? Can't see it. No, how about somepony from further back… Cadence. Twilight shivered, imagining spitting Shining Armor's semen into Cadence's mouth, then Cadence delivering it to her for impregnation. Taking care of me just right. Hmm. While she's also fucking Vinyl, of course. Just to be fair to him.
Celestia cut in, asking, "Twilight, are you all right? You shuddered."
Twilight's eyes came back into focus. "I'm all right. I guess we'll just to be careful to avoid letting our shared genetics become relevant. Sound good to you, Vinyl?" Vinyl nodded.
Celestia perked an eyebrow. "I see. Well. I leave how you handle it up to you. If you would like to talk about it later, I may be able to give you further information on how this happened."
Twilight looked to Vinyl. "No need; I think we're good."