Twilight Gets her Data On

by Captain_Hairball

Rating: mature
Tags: Slice of Life, Porn, My Little Pony: Friendship is Magic, Fetish, Shining Armor, Sex, Twilight Sparkle, Profanity
Length: 2654

Twilight Sparkle has noticed that Shining Armor has been acting strangely around her for a while — basically their whole lives, actually. And she has data to back up her claims .

Twilight Sparkle has noticed that Shining Armor has been acting strangely around her for a while — basically their whole lives, actually. And she has data to back up her claims: chiefly, his near-constantly erect state at the sight of his darling Twily.

Set between about 6:06 and 6:07 of season 1, episode 1.

Warning: Contains Sparklecest.

Edited by Cerulean Starlight & Rasael.

Published 2016-09-14 13:40:01 UTC
Last updated 2016-09-14 13:40:01 UTC

The Facts Stand Up for Themselves

Author's Note

This story contains fictional depiction of erotic parent/child and/or sibling incest. This is intended as a fantasy. Fiction is a safe space. In real life, the author does not consider consent possible in these relationships and does not support or condone them.

The Facts Stand Up for Themselves

Twilight burst in through the door of their parents’ house, soaking wet. “She’s punishing me!” she wailed, throwing herself onto the couch next to Shining Armor.

Outside thunder cracked, rattling the window frames. Mom and Dad were out in this storm somewhere. Shining hoped they were okay.

Shining looked up from his book. “Who did what to you?” He closed the Oubliettes & Ogres Dungeon Master’s Guide with intent. The hairs of his mane stood on end. Somepony was going to pay.

Twilight was curled up in a pudgy little ball of woe, sobbing into a quilted throw pillow. She didn’t seem to have heard him.

“Twily,” said Shining, sitting up on his haunches and scooting closer to Twilight. “Twily, who’s punishing you?” His tone was soft, but it was a front. He was preparing himself for extreme violence in his sister’s defense.

“Pr… Pr… Prince…” Twilight sobbed

Oh sweet Faust, Prince Blueblood! What had that cad done to her? Well, prince or no, he’d learn that nopony was above the reach of the royal guard.

“Princess Celestia!” howled Twilight.

Oh. All right, maybe she was.

“But the Princess loves you,” said Shining. “You’re literally her favorite pony.”

“She said I needed to stop reading dusty old books! She said I needed to make some friends!”

Shining Armor bit his lower lip. He was surprised she’d been so blunt, but her Highness had a point. “Could I get some context for that? That really doesn’t sound like her.”

Twilight nuzzled against his chest. He looked down at her soft, round, innocent face and he had to adjust his position on the couch. Because Shining Armor had a terrible secret — he knew other colts found their sisters’ bodies repulsive. He never had. He knew it was wrong, but his sister’s sweet scent, plump haunches and voluptuous belly filled him with desire every time he saw her. “I wrote her a letter. I wrote her one innocent little letter and now she’s sending me to Ponyville! It’s not fair!”

“Twily, what was this letter about?”

For the first time since she came in the door, Twilight stopped crying. She rubbed her cheek against his neck. “Oh, just about the Summer Sun Celebration. I’m sure lucky to have a loving older brother like you. I feel so much better and we totally don’t need to talk about this any more. Let’s play Scrabble instead.” Her hooves slid to his chest, frogs tracing the muscles. His cock pulsed against his belly, filling him with shame. His poor, innocent little sister didn’t know what she was doing to him!

Shining narrowed his eyes. “You didn’t write her about you-know-what, did you?”

Twilight squirmed. “I might have. Why?”

“I thought we agreed you weren’t going to worry about Nightmare Moon coming back. I thought we were going to let that go.”

“But my research is sound! We need to be prepared for this!”

“You’re obsessed, Twily. You’re being a c….”

“Oh no. You are not using the ‘c’ word around me. I thought we agreed never to use the ‘c’ word.”

“You’re being a crackpot, Twily. It’s a crackpot theory. Nightmare Moon is dead. Celestia killed her.”

“She sent her to the moon! It’s what all the books say!”

Shining facehoofed. “That’s a euphemism. Everypony knows it’s a euphemism. Nopony takes that literally.”

Twilight’s eyes, still puffy from crying, flared with rage. “Oh. Really. When has anypony ever used that as a euphemism except when talking about Nightmare Moon? Hey remember when Grandma got sent to the moon when we were little?”

Shining Armor tried to interrupt. “Twily, I…”

“And remember when Great Uncle Lebensraum got sent to the moon and everypony acted like they were sad, but really we were all relieved that we didn’t have to ignore his tribalist rants any more?”

“But Twily…”

“Hey, Shining, how many ponies have you sent to the moon in battle?”

Shining blushed. “None, I’ve never been in battle. Twily…”

“Celestia is incredibly powerful! If she can raise the moon every night, why can’t she send somepony there? And if she sent somepony there, why couldn’t that pony come back?”

Faust damn it maybe little sister had a point. “But if she can come back, I’m sure Celestia knows about it, sis. Maybe there’s a reason she’s sending you to Ponyville. Maybe she’s trying to protect you.”

Twilight opened her mouth and closed it again. “But I… but I could help her.”

Shining wrapped his arms around his beautiful, innocent little sister. “I’m sure you could, Twily. But she’d rather you be safe. I would, too. Why don’t you go get packed, and we’ll order dinner. Leave this to the professionals.”

Twilight slumped, defeated. “Okay. I guess there’s not much I could do against Nightmare Moon anyway. I’m just a stupid little pony.”

“Nothing stupid about you, Twily.” Shining watched her walking towards the stairs. Powerful rump muscles bunched and unbunched beneath sweet schoolfilly fat and a velvety purple coat. Her tail swayed from side to side, giving him teasing glimpses of the treasures nestled in between those perfect cheeks. Watching his sister leave the room was one of the most shameful, and most wonderful, pleasures in his life.

He’d just started unconsciously humping the sofa when something occurred to him. Twilight wasn’t stupid. Or a crackpot. She was thorough and precise and he’d bet his commission she was going to make a rational cost–benefit analysis before picking what she wanted for dinner. If she thought Nightmare Moon was coming back, maybe there was something to it. He’d studied Phalanx’s account of the Sisters’ War in officer candidate school. Pony killing pony. Thestrals sweeping pegasi from the skies. Blood in the streets of Canterlot.

Shining Armor swallowed hard, and forced himself to speak. “Twilight.” She looked back at him over her shoulder. The gentle curve of her neck made his heart flutter. “Twilight, I love you,” he said.

She giggled. “I love you too, BBBFF.”

Shining Armor tried to explain further, but his throat was suddenly too dry to do any more than make an embarrassing creaking noise.

Twilight laughed. “You’re a silly pony. Order us pizza before you lose the ability to talk entirely, okay? We should get mushrooms for protein, green peppers for roughage and mouthfeel, and extra cheese because it’s so tasty.”

———

They reclined next to the empty pizza box, heads about a foot apart from each other. Shining was too full to lie on his belly, so he had to lie with his back to Twilight to hide his bobbing blue erection, which hadn’t gone down an inch all evening. His body was being even more of a traitor to morality, law, and reason than usual. Both of them lay there, quiet except for their breathing, while rain hammered on the windows.

Then Twilight burped. They both laughed.

“So, BBBFF,” said Twilight, sparkling eyes looking over at him from under her straight bangs. “Not to ruin the moment, but I can’t help but be curious what you were trying to work yourself up to, earlier.”

Shining Armor found his mouth wouldn’t work. Understandable — what he wanted to say was a big deal. Once it was out there, there was no turning back, for better or worse. Probably worse. Massively, catastrophically worse.

Twilight rolled upright, and crossed her forehooves in front of her. She was smiling. Her expression looked… smug? Oh no. Smug Twilight and bad ideas went together like pizza and extra cheese. “Because it’s common for a brother to say that he loves his sister. And yet… well, I know that my grasp of the nuances of tone and facial expression is not the best, but I know enough to tell when there’s something more a pony wants to say.”

Oh, sweet, innocent Twilight. Totally unable to understand the depths of evil that lurked in her older brother’s heart. “Nothing. There was nothing else I wanted to say. You’re clearly mistaken.”

Twilight flicked her tail like a cat closing in on a cornered mouse. “Oh, I don’t think I’m mistaken. I’ve been collecting data for some time, and I’m forced to conclude that you feel more for me than is common for a brother to feel for his sister. I think these feelings are very strong. I think they’re sexual in nature.”

Shining rolled over and scooted back from Twilight, his hard cock dragging painfully across the floor under his too-full belly. “Twilight, no! No, I’d never!”

Twilight hopped up, grinning. “But you would! You totally would! You know how I can tell?”

Shining’s ass bumped up against the far wall of the living room. His ears laid back flat against his skull. “Um, no?”

Twilight bounced up and down excitedly. “Because your penis is erect!”

Shining Armor made a strangling squeaking nose deep in his throat. “Twilight! Language!”

“It’s the number one sign of male arousal, indicating a readiness for sexual penetration with a willing female! And it happens to you around me constantly! I’ve been keeping track of this since I first became sexually active at age twelve.”

Shining Armor felt the floor shift sickeningly underneath him. He rubbed at his ears. Surely he’d heard that wrong. “Age twelve?”

Twilight pulled a notebook full of line graphs and raw data out of the end table drawer. “You were fourteen at the time, and pretty much constantly erect, so I didn’t notice the pattern right away, but there’s a definite pattern to the mares you’re interested in. Mom and my babysitter topped the charts until I hit sixteen or so, then I’m number one after that. I mean, okay, sample bias; Cadence wasn’t coming around much by then, but even adjusting for that I’m still ahead of her by a solid four percentage points!”

Shining’s jaw fell open. “You keep that in the living room? What if Mom sees!”

“Oh, she knows. I can’t gather all this data myself.”

Shining felt queasy. “I thought she never noticed.”

“Oh, she noticed all right.” Twilight snapped the notebook closed and looked up at Shining. “So. Do you want to have sexual relations?”

Shining’s mouth had stopped working again.

“Oh, come on,” whined Twilight, stepping forward to rub her cheek against Shining Armor’s neck. “This is Canterlot! We’re unicorns! Birth control spells are easy and effective! Our refined intellects have allowed us leave behind the outdated, hypocritical morality of the earth ponies and pegasi!”

“That’s tribalist, Twilight.” He wanted to pull away. He really did! But instead he rubbed his face against her neck in return, inhaling the soft, clean scent of her fur. His cock was so hard it hurt. It felt like it was going to explode with every beat of his heart.

“It’s not tribalist if it’s true! Come on! I wanna, I wanna, I wanna!” She raised her head and bounced up and down on her tippy hooves. He ass cheeks jiggled like overfull wineskins, ripples moving back and forth through her cutie mark. He felt guilty, betrayed, objectified, and unbearably horny. All of that made him very, very angry.

“Shut up!” He surged to his hooves, grabbed Twilight in one of the haykido throws he’d learned in hoof-to-hoof training, and threw her onto her back. She skidded away from him, belly up on the living room rug, hind legs sprayed. The throw had knocked the breath out of her, but her pussy still mocked him. The lips, so plush under ordinary circumstances, were swollen with lust. Clear fluids glistened, dripping down between her fat cheeks onto her plump little ponut. She looked up at him, sweet eyes wide, mouth working voicelessly. Shining Armor lunged forward and effortlessly plunged his aching cock into her hungry, willing pussy.

It felt. So. Amazingly. Good. Better than either of the other mares he’d been with. Sister’s pussy was hot, silky, and tight. Wonderful beyond belief.

His sister’s pussy. Oh no.

“Twily, I’m sorry! I’m so sorry!” wailed Shining, unable to stop his hips from moving. If the feeling wasn’t enough to make pulling out unthinkable, the sight of the ripples moving through her round belly with every thrust were.

“Don’t be sorry! Harder! Have intercourse with me! Intercourse! Intercourse!”

She did want this. His little sister was all grown up. A big, curvy, post-doc filly whose eyes were filled with lust for her big brother’s body, and whose sweet voice was calling out her wild, technically accurate passion.

“I love… unf!… the way your exceptionally large… oh!… penis fills my… unf!… vaginal cavity!”

With dirty talk like that, he wasn’t going to hold out much longer. His balls burned, tightened, pressure building inside of him. He tried to slow down, to hold back, to delay his pleasure for Twilight’s satisfaction, but every time he’d start to, Twilight would buck up against him and urge him to go faster. He closed his eyes, trying to think about hoofball, military drill, requisition forms, anything but how good this felt, but the wet sound of his balls slapping against his sister’s pussy filled his ears, and he was gone. Cum pulsed through his cock, filling every nook of his sister’s hot little tunnel.

Shining Armor’s eyes snapped open in alarm. Sister. Hot little tunnel. No. What had he done? He pulled back, cock popping out of Twilight, spraying cum across the already huge wet spot on the rug. “Oh my Faust what have I done,” moaned Shining, staring in horror at the massive puddle of white goop filling his sister’s gaping pussy.

“Oh no,” said Twilight, rolling over onto her side, horn glowing bright purple. “No post-coital guilt for you! I haven’t had an orgasm yet!”

Suddenly Shining Armor’s cock was hard again. It was battered from his rough passion and his sister’s impressive vaginal tone, so being hard again so soon hurt like buck, but in a way that only made him more horny. He wanted her again, conventional morality be damned. He narrowed his eyes angrily. “Twily, did you just put a mind control spell on me?”

Twilight grinned. “No. I put a penis control spell on you. Totally ethically fine. I think.”

Shining glanced at her cum-splattered rump. He knew a stallion’s duty to a mare, but he’d always made sure to do his partner first in the past, so he wouldn’t have to get his own stuff in his mouth. “Do you want me to… um…”

Twilight giggled. “Oh I wouldn’t make you. You’re not ready to hear my research on your latent bisexuality yet.”

Shining gasped. “My what?”

“Nothing. Come on up to my bedroom; I’ve got some great toys you can use on me up there.” She got to her hooves, and followed her across the living room and up the stairs, hypnotized by the sway of her ample rump cheeks. “We’re gonna have a lot of fun together! We’ll need a beard, of course — incest is more accepted than it used to be, but still something to be discreet about. Ask Cadence on a date next time you see her. I think you’ll be pleasantly surprised at the results. Of course, I’ll pretend to know nothing about you two when I find out… but… well, three in bed is always more fun than two.”

Shining Armor hesitated at the base of the stairs.

“Come on!” said Twilight. “My chariot leaves in seven hours! I still need to pack! And do I need to remind you I haven't come yet?”

Shining Armor grinned from ear to ear. After tonight, he could face a thousand Nightmare Moons without regrets.