“Ewww… a kiss with my brother?” Twilight recoiled, sticking her tongue out of her muzzle in disgust. ”Th-that’s… weird right?”

“Not THAT kind of kiss, Twilight…” Cadance grinned evilly, not for the first time that night, her eyes flicking down toward the throbbing sausage standing proudly between her husband’s legs.

“Honey!” Shining exclaimed. “This is Twilight you’re talking about!”

“So? She’s not a little filly any more Shining, she probably knows all about making stallions learn all about the magic of friendship.” Cadance waggled her eyebrows.

“Actually, I’ve … n-never…” Twilight began, her eyes glued on the end of her brother’s menacingly fat, dripping, black cockhead.

“It’s just like an ice-cream cone Twi, it’s really not that complicated.” Starlight mumbled.

“There you go! Thank you, Starlight!” Cadance laughed, happy to have another pony back her up. “So, Shining, why don’t you just lie back, let your deepest, darkest fantasies come true, and let Twilight make it all better.”

Shining’s swallowed heavily, eyes racing between his overly-encouraging wife, his little sister, and his throbbing phallus. “Twilight… would never… she’s my little sister!”

Twilight had been leaning closer and closer to the big black cock as the discussion had gone on. Its quivering, drooling tip was only half an inch away from her nose now, and the scent of her brother’s recent orgasm mixed with the smell and musk of the juices he was extruding was heavily intoxicating.

She’d seen blowjobs, in magazines and in pornos, she knew how they worked. She’d never been able to imagine just what it was that could make a mare want to stuff something like that in her mouth… but with this potent, sexy, virile shaft in front of her… she was beginning to change her mind.

But this was her brother! The last time her lips had touched him was when he’d skinned his knee playing backyard hoof ball with his friends. She’d playfully given him a kiss on his scratch to make him feel better. He’d immediately complained about girl-cooties and swatted her away, complaining that she was altogether far too baby-ish trying to kiss it better. Now she was staring at his cock, not his skinned knee… and cooties were a distant nothing compared to the burbling juices slipping from his tender cockslit. Could she really kiss… that?

Yes.

“Twilight, you don’t have to -oooohmmy Celestia!” Shining’s statement was cut-off as Twilight leaned forward, her nose booping the end of his penis.

Twilight looked up into her brother’s deep blue eyes as she opened her mouth, let her tongue drop out of her mouth, then place a long, languid lick that started below his glans and lovingly wrapped up to his juicy orifice.

That taste, that sensation, the one that had filled her so heavily with his potency just moments before… now she was drinking directly from the source… and she liked it. Opening her mouth wider, Twilight tried to wrap her lips around Shining’s fattened glans. He’d calmed down some since his flaring ejaculation a few minutes before, but it was still no easy task trying to get such an impressive mushroom into her mouth.

“Wooo! You go Twilight!” Cadance cheered.

But she barely heard her. Twilight’s whole focus was on the incredible taste of her brother’s stallionhood, she was desperate to get more of it, on her tongue, down her throat… in her belly. She took deep, sucking, grasping draws, like she was working on a milkshake that was far too thick. Her tongue roiled and lashed without purpose, she had no talent or experience, but she would make up for that with enthusiasm.

“F-f-fuck!” Shining moaned from above her, as she managed to jam the entirety of his head into the back of her mouth, just barely clearing her teeth. She felt her brother’s powerful hooves carefully grip the back of her head, not to push more of his huge size into her, but to stop her from assaulting him so rapidly. “T-twi!”

But she was possessed now. Shining’s cock was stiffening inside her mouth, growing again as she fellated him, moving back and forth with little gulping drools. She shut her eyes and tried to focus on her breathing, as she felt her big brother best friend forever start to scrape the back of his throat with his thick, hot, tool. Twilight could feel the drool dripping from her mouth as she schlicked back and forth slowly, groaning and gasping as she tried to swallow more of that black monster.

“Oh… oh shit… Tw-Twily!” Shining Armor’s hooves gripped and clenched at her mane, as her brother began to try to pull more of himself into her. She could feel the juice spilling directly down the back of her throat now - she was gagging on his massive cock… but she wanted more. Her hooves reached out, gripping the black shaft filling her face - she wasn’t even close to the medial ring,... and the amount of cock that her hooves slid down before reaching her brother’s warm stomach terrified her… and excited her.

He was such a stud. More than her wildest imagination. More than her most debauched, blanket-twisting, pillow-humping fantasy. And now he was inside her. She had his balls in the frog of her hooves!

“Twilight! I’m… I’m g-getting… c-close…!” Shining grunted, his body starting to quiver and jerk, his balls jumping and clenching.

“Already!?” Cadance exclaimed in disbelief as her husband’s lack of forbearance surprised her for the second time that evening.

The flask! Twilight’s eyes shot open as she remembered just WHY she was here. With her brother. Doing this.

She started to pull back, to withdraw her brother’s cockhead from her gullet, as she levitated the flask into position near her chin. She’d pull him out, slip the glass flask under his glans, and listen to the soft pinging sound of shooting liquid striking the inside of the nearly empty container, and she’d have all the essence of unicorn she’d need.

But it was too late.

She felt the throb of her brother’s cock on her tongue as the first pulse shot through his shaft. Like a dentist wrenching her mouth open for an inspection, her brother’s rock-hard flesh bulged and grew in her muzzle, stretching her jaw to a level she didn’t think possible. At the same time, her brother’s cockhead mushroomed out into the powerful, aggressive flare she’d witnessed first-hoof only minutes before… only now it was flaring in the back of her throat.

For a brief second, Twilight realized she couldn’t breathe, her esophagus completely plugged with big, fat, unicorn cock. She’d taken a breath just before this had happened, which saved her from a panicking, choking, gasping disaster… but it didn’t save her from the flood that followed.

The whole burst of her brother’s first shot exploded into the back of her throat, coating it with his thick, creamy coat of virile paint. Twilight had no choice but to swallow and swallow and swallow. It felt like she was trying to chug an entire pint-sized jug of Pinkie’s extra-thick vanilla milkshake… if the milkshake were being tube-fed down her throat, and it was hotter and thicker. Each swallow did little to clear the blast before hand - most of her brother’s thick ropes were being blasted directly down into her belly, splashing her fuller and fuller with his batter, as if her gut was an oversized womb.

All she could do was take it. There was no way to extract his flare, which had knotted itself inside her, jamming against her throat. She could only paw weakly at his chest, moaning and choking on his orgasmic cock.

“F-f-fuuuuuuuuck!!!!” He groaned out, giving out once last buck, before slumping back onto the couch.

Twilight was dragged forward as he fell back, her tired and sore-throat still jammed with Shining’s big fat flare. Twilight managed to open her eyes, her face filled with stallion-cock and pressed against her brother’s lower stomach. She could see him panting and sweating in a heap, his whole-body quivering and shaking. Her face was starting to turn red from lack of oxygen, and as soon as she felt Shining’s terrifying, throat-blocking flare soften even the slightest bit, she tore the thing from her without too much consideration, spittle and cum splashing from her sore jaw as she took a well-deserved and deep breath.

Shining winced and mewled, the sensation barely registering as he basked in his orgasmic bliss.

Twilight coughed and hacked, swallowing over and over to try to get some sensation back into her mouth and throat.

“Holy horseapples… are you OK Twilight?” Starlight asked, placing a hoof on her friend’s back.

“You did amazing Twilight.” Cadance cooed, her hooves straightening the purple alicorn’s mane. “I can’t believe you actually did a deep throat on your first time! Even I didn't manage that!”

Twilight put a hoof to her chest to steady herself as she pushed back up away from her comatose brother, and the giant cock, which now lay floppy and messy against his belly, just as drained as he seemed to be.

“F-fat load of nothing it did for me, though…” Twilight coughed, as she hoisted the almost-empty flask, which still held only a few squirts of her brother’s ejaculate. “I doubt that that Shining’s ejaculate will work as a reagent if I hork the whole thing up... “ Twilight patted her belly, feeling it squish and slosh. “I must have drunk a gallon of the stuff!”

Cadance and Starlight chuckled, sitting back on the couch, trying to hide their mirth as they looked between the disheveled Twilight and the half-snoring stallion.

“It’s not funny guys!” Twilight stomped a hoof. “The whole point of this was to get Shining’s seed into a container, and instead I’ve shot it all over the room, over you two, over my face, and down my throat… basically everywhere BUT the place I need it!”

Starlight got a wry grin, “I dunno Twilight, with how you were swallowing that stud-sausage I’d say you really did need it-”

“Zip it.” Twilight cast a spell which pulled an exceptionally large zipper across her friend’s mouth.

“I’m sorry about that, Twilight.” Cadance sighed, looking over at her husband. “You never can tell what can happen in the course of a real rut.” She prodded her non-responsive husband, earning only an incoherent moan from him. “And I’m afraid both little and big Shining are out of commission for now.”

Twilight looked down at her brother. Indeed, his stallionhood, previously a proud flagpole of rigid maleness… was now a flaccid, tired, sticky snake of exhaustion, laying in a floppy heap on his heaving stomach.

“S-seriously!?” Twilight groaned, plopping down on her haunches with dismay. “After I went through all of that, I’m going to go home empty-hooved? I’m going to have to do this again!?”

Cadance got that sparkle in her eyes again, and she crossed her arms, her mind already scheming with devious efficiency. “Well… maybe… maybe there’s a way…”

“Hmm? Really?” Twilight’s ears perked up. “C-could I maybe… do something while he’s asleep?”

“No…. not quite... “ Cadance giggled. “Stand up and turn around…”

Twilight arched an eyebrow with curiosity, unsure what her sister-in-law was going to do… “Oh-kay….?” Carefully she stood up and turned away from the grinning alicorn and her friend, watching with curiosity but unable to speak.

Twilight felt a slick pressure push under her half-flagged tail, quickly slipping between her hot marelips and sliding from just under her ponut, down into her honeypot, taking a moment to tweak her throbbing lovebud. “Ohhhhng!” Twilight squeaked, the magical touch delightfully teasing and playful. “H-hey!”

Twilght quickly turned around to face her mischievous sister-in-law, who was holding a small dollop of Twilight's nectar in her magic field.

“This will do quite nicely… you’ve heard of smelling salts, right Twilight?” Twilight nodded as Cadance levitated her magical field over to the unconscious stallion. “Well this is the next best thing for a tired stud…” Cadance hovered the ‘eau de Twilight’ under Shining’s nose, wafting it there for a moment.

Twilight watched with wonder as her brother’s nostrils twitched, then flared, drawing in deep huffing breaths. He was reacting to her!

“C’mon lazybones… or should I say lazybone?” Cadance laughed, before smearing the sticky marecum across Shining’s nostrils.

“Mmmmghhnnn….” Shining groaned, beginning to stir and nicker.

Twilight watched in fascination as her brother’s cock began to throb and pump again, like a thick firehose filling with water pressure, twisting and jumping, pumping up fuller and fuller and fuller… rising with each heartbeat and stiffly erecting itself away from his body.

“THAT’s my stallion!” Cadance giggled, patting her husband’s forehead and clearing his sweaty brow as he continued to rouse from his exhausted blissful post-climactic bliss.

“MMHMMFF!” Starlight coughed, pointing at her mouth.

“Oh, sorry Starlight.” Twilight mumbled, finding it hard to take her eyes away from her brother’s pumping, pulsing, re-risen cock. With a quick flip of her horn she released the muting spell from her pupil.

“Ah… ahem… thanks.” Starlight grumbled. “If you’d given me a chance to keep speaking, I was GOING to say that I think I might have an idea to help you with your harvesting trouble.”

Twilight snapped her head away from her brother, whose eyes were fluttering open over to her friend with a growl and a deadpan look. “And… you’re just deciding NOW to share this?”

“Hey! I didn’t think that you’d have such a tough time aiming!” Starlight’s horn glowed with her purple aura, and she snagged her saddlebags from over by the door. “But since you have been… here!”

Twilight saw the small package float out of Starlight’s bag and took it in her hooves. A small plastic container printed in a lascivious crimson. COOLCO BRAND CONDOM - RIBBED FOR PLEASURE - SIZE M

“Honestly, I got the thing as a joke secret Santa present from Rarity two years back, not even sure if it’s expired but…”

“...but if we use this then there’s NO WAY that we won’t get every drop from Shining regardless of what happens!” Twilight’s wings flared out with happiness. “Perfect! This is perfect!”

“Unghh… what’s that amazing smell?” Shining groggily pushed himself to a seated position with one hoof. “...reminds me of lilac and wet marehoo-…” Shining shut his mouth as his brain finished rebooting and he slowly remembered how he had come to find himself here, covered in his own cum, next to three cum splattered mares… one of which happened to be his sister.

“That would be Twilight’s pussy, dear.” Cadance smiled.

“O-oh…” Shining swallowed again, pushing himself up to being fully seated. He blinked and sniffed, trying to clear his nostrils of the poignant musk and failing. “It’s… uh… w-wow… not gonna lie… I… I’m having trouble concentrating.”

Twilight cleared her throat. “W-well that makes two of us, Shining. But I think that we can give this one more go, and this time I think there’s no way I can blow it.” She snagged a corner of the COOLCO condom package in her mouth, biting into the wrapper and pulling the thing open. “See?”

Shining shifted uncomfortably, his eyes bouncing back and forth between the condom and his little sister, holding the thing as prim and happy as the cat that caught the canary. “A c-condom? Y-you really want to go… all the way?”

Twilight felt her breath catch in her throat. She hadn’t even been thinking about that! It had never even entered her mind! She looked at the big, black, throbbing cock in front of her, exciting and erotic in its own terrifyingly gargantuan way… and the stallion it was attached to, the only colt she’d ever loved… truly loved… with his big dumb heart, and his powerful chest, and his winning smile. She felt the pit of her stomach (still filled with his bubbling seed) sink, as she realised that… yes, she DID want that, somewhere deep down.

But she couldn’t admit that!

“N-no! No!” Twilight blushed again, squeaking. “I… I mean that we can put the condom on and then you’ll… deposit in there… so nothing will be wasted or misfire… that’s all…”

“Oh. OH!” Shining coughed, then nodded. “Y-yeah! Oh man… I don’t know what I was thinking! That makes sense.”

“Want me to help slide the thing on, Twilight?” Cadance offered. “They can be tricky if you haven’t done it before.”

“No!” Twilight cried out, swatting Cadance’s hoof away from her husband’s penis. “I have to do this!” With a deft touch of her magic, Twilight hovered the condom over to her brother’s massive, stiff pole.

“Other way, Twily.” Shining grinned as his sister flipped the little roll of silicone and slid it over the crest of his dick.

Twilight chewed her tongue in concentration as she began to unfurl the little slip of condom. She watched her brother’s face as it winced and grimaced, the black flesh of his big cockhead bulging obscenely against the little bit of clear wrapping. “Wh-what’s wrong?”

“Usually he gets the magnum XL size.” Cadance giggled, pointing at just how strangely the condom strained and stretched under the strain of Shining’s massive, princely cock.

“It… it’ll work!” Twilight grunted, as she rolled out the rest of the condom… which ended pathetically just past her brother’s big, fat medial ring… leaving a good 5 inches of his 17-inch organ completely bare. “Well… it’ll work for what we need it for, anyway.” She looked up at her brother, who was looking back at her, the big pole the only thing between their gazes.

Twilight swallowed slightly and took a grip on her brother’s base, where the condom hadn’t reached. “I-I’m… going to start… again…” Shining simply nodded back at her.

Twilight began to slowly pump her brother’s base, slowly marveling at just how thick he was down there, before working her hooves up to the bulging plastic that could barely hold him. It felt like she had a balloon in her hooves that was strained to the absolute limit, totally ready to pop. It struck her again just how… stallion-ly her brother had become at some point. He wasn’t the colt of her childhood… at some point he’d gone and grown up… had become an absolute stud, in every sense of the word.

He was now her BIG brother best friend forever. She bit her lip, looking at the drips and drops of precum slicking the inside of the bulging silicone. She kept pumping, but it felt… wrong. Not the obvious wrong of her hoofing off her brother… but that she was doing it this way… so cold… so clinical. Just pumping him off like he was some kind of farm animal. After they’d been so close before. After he’d even almost suggested… that they… buck.

Gods she wanted more.

“T-twilight…?” Shining’s question interrupted her train of thoughts. A shiver ran through Twilight’s back as she stopped pumping and looked up at her big brother. It seemed like he was too ashamed to meet her eyes, like he had something difficult to say.

“Y-yes? Am I… doing OK?”

“Yes! Yes.” Shining answered quickly. “Really good… I just…” he bit his lip, looking over to his wife. Her eyes looked as big as dinner plates, and her wings were fully extended, like she was about to get what she had wanted all night long. “...I… never mind.”

“Shining, dear...” Cadance groaned, stomping her hoof. “Go on! Speak from your heart!”

Shining hesitated, chewing his lip as he sought the right words. “Twilight… I… augh... I can’t!”

Twilight tilted her head, so that she could see Shining’s face without having to stare through his penis. “What is it? You can tell me, Shining.”

Shining let out a big sigh, as if the weight of the world was compressing him into a pancake. “Twily… you know… when you showed me the condom… and I thought you meant that you wanted to… well… wanted me to… y’know?”

Twilight was silent, her ears pounding as she wondered if Shining was going to say what she thought he was.

“Well… I… was really excited for that.” Shining swallowed. “I… don’t know if it’s just this crazy night… or the fact that I’ve got your scent jammed up my nostrils and it’s more fragrant than that one time back when you were in high school and your heat came early…. But…”

Shining’s deep blue eyes locked with Twilight’s as he looked up guiltily from his rigid penis. “I… I want to rut you, Twily.”

Twilight’s mouth fell slightly open. Her big brother, the one who’d given her piggy-back rides, who’d taught her how to fly a kite, who’d read her stories about Starswirl the bearded, who’d been there to give her hugs and tell her dumb jokes when she felt down… he wanted to fuck her.

And she wanted him to do it.

Author's Note

Twilight, I'm pretty sure you can't even make the excuse that this is even remotely scientific now.