Surprising Your Mare

by TheDudeAbides

Rating: mature
Tags: Random, Shining Armor, Sex, Twilight Sparkle, My Little Pony: Friendship is Magic, Princess Cadance, Romance, Porn, Fetish
Length: 8327

Shining wants to surprise Cadence for their anniversary, so he asks Twilight if she could maybe enhance his "features" a little. Things don't go as planned.

TRIGGERS: Macro, Futa, Growth, Size Difference, Cock Worship, Hyper Cocks, Incest (duh), Autofellatio, Fellatio, Anal, Spitroasting, Cuuuuuummmm

As Shining's anniversary approaches, he deeply considers what he should get for his special somepony. What do you get the princess of love on such a special occasion? Upon realization of the perfect present to his wife, Shining visits his sister to put his plan in motion. With Cadence arriving in only mere hours, Shining hopes that a night full of deeply romantic lovemaking would truly project his love.

But not everything goes the way we want it.

A fic made up of the majority of my fetishes sans R63 and Preggers. This was a toughy to write because I wouldn't stop getting aroused. Hopefully you can enjoy it as well! :D

Cover art by the awesome Violise!

Edited by: OkemosBrony, Jake the Army Guy, Anonymous

Moral Support/Prereading: Megapone, Zippysqrl, Violise and MrLucksman

Published 2014-01-17 02:10:03 UTC
Last updated 2014-01-17 02:10:03 UTC

Sizing Up

“Are you really sure about this big bro?” Twilight inquired towards the quite flustered colt standing before her. Twilight had been spending the majority of her days at Celestia’s old castle, pouring through the many magical tomes that populated the archaic library. Despite being far from home, Spike would regularly check up on his “big sister,” making sure that she was eating and comfy while researching in the barren halls of the castle.

Shining Armor was absolutely certain. “Twilie, you know that Cadance is almost impossible to surprise. I’m sure she would never predict something like this happening. She keeps telling me she always wants that extra umphf…”

“I’m not sure this is a great idea; I mean, most enchantments like this are highly dangerous. They reassemble the target at a molecular level. What if I mess up?” She glanced towards her brother with a rather concerned look. She loved Shining so much that taking such a risk greatly outweighed her scientific inquiries.

“Look, I understand your concern for me, but you’re a princess and my sister. I know you’re smart enough to pull this off. And even if something does happen, we're in the middle of Celestia and Luna's private library! I'm sure there something in one of these books that could fix anything!”

“But-”

“No buts, Twilie. You’re my little sister, and I believe in you. You’re a smart mare; I wouldn’t have gone to you with this if I didn’t trust you.” Shining Armor moved closer to her, lying down beside her as he put his foreleg around her neck.

“Even so...it seems a bit wrong for a brother and sister to do something like this….”

Putting a hoof to Twilight’s lips, Shining whispered ever so faintly into his dear sister’s ears, “No pony needs to know~”

A shiver ran down Twilight Sparkle’s back. Her wings cringed a little. Still, she knew that her big brother was depending on her, and she adored helping out a pony in need.

Twilight sighed. “Alright. Just give me a minute to set up.”

“Thanks Twilie, you’re the best sister an older brother could ask for,” Shining said with a grin, giving his beloved sibling a quick peck on the forehead.

“Are you ready, little sis?” Shining asked, elated that he was able to convince his sister to go through with performing such a complex spell. Shining Armor sat on the concrete floor, his stallion endowment peeking out between his front legs at full attention. A droplet of precum dribbled from the tip of his erect cock, sliding down the rigid head before falling to the cold abyss with a tiny plop. Ready was an understatement regarding the Royal Captain’s current mental state; his mind was playing out the series of events that would be soon to follow. Shining would meet Cadence in Ponyville, the two would go out for a romantic picnic in the fields overlooking the quiet, timid town, have a nice dinner, enjoy some passionate smalltalk while watching the burning sun rest for the night, and then he would rut his princess senseless with his enlarged stallionhood as the moon shimmered brightly above them. His plan was absolutely perfect.

Confident that she had gone over all of the necessary precautions, Twilight lit her horn, igniting a magical lavender aura around it. “Here it goes,” Twilight murmured, a pang of unease encapsulating her words like a foreboding shadow. Soon her magic began to swirl around her BBBFF, wrapping him up as if he was a gift.

“Ohh, Twilight, this feels so good~,” Shining moaned. His cock surged with unprecedented warmth, his sister’s magic jittering through his veins as his jet black flesh tingled from the stretching. His stallionhood bulged as he felt his girth expanding, slowly gaining inches in diameter. Shining’s tool was nothing to laugh at to begin with; it was a rather impressive display of masculinity, graced with a fair bit of length, topping out at nineteen inches of bestial flesh. But his girth was something else entirely, for among his stallionhood sported a width that measured at the upper end of six inches. And while he could easily fill his princess to the hilt, he knew that she could accommodate way more.

Shining couldn’t help but bring his hooves up to his cock, rubbing the sides gently as he felt his penis grow to new proportions. Moans bellowed from his throat as the bulging veins on his stallionhood obstructed the otherwise unimpeded friction that rolled up his shaft from his hooves. His raw penile flesh stretched as it took a new form, bulging outward like expanding rubber.

“I REALLY DIDN’T NEED TO KNOW THAT!” Twilight huffed, her eyes wincing from having to perform such an intense spell. The sheer intensity of the magic took corporeality in large plumes of wind, wisping around the room littered with tomes. Pages flipped frantically as the gusts threatened to tear the room apart. The tattered wooden furniture rattled as the wind intensified, splinters jettisoning from the grain. Curtains were eviscerated from the windows as the panes wobbled in dangerous resonance. “I don’t know if I can keep a hold of it any longer!!” Twilight exclaimed.

Her brother called back as he continue to stroke his meat, “Just keep going Twilie. You’re doing great~” Precum the size of a filly’s head trickled out of his growing tool, running down the length of his massive shaft. Shining conceded himself to the foreboding bliss, his cock radiating a powerful warmth threatening to consume the stallion. Convulsing as his member rubbed up against his burly chest, Shining let out a moan, his pre mottling his snowy fur in gray splotches. His three foot stallionhood had reached up to his neck at this point, as his testicles bloated from the increased production of his sperm. His balls swelled, like they were being charged with helium, growing bigger than his hoof. Shining only wanted more. He wanted, no, he needed it to be bigger.

Grunting in reply, Twilight buckled down and continued to weave the spell, when she started to feel a bit quaint. The sudden gusts of wind were kicking up a storm of dust and...it was too late. Reeling backward, Twilight sneezed as she let out a burst of magic energy directly at her big brother. Her eyes cracked open at the recoil and she quickly dropped her spell, rushing towards Shining Armor who had been blasted backward towards the wall.

“OhmygoshOhmygoshOhmygosh, BBBFF are you okay? Please say you are okay! Oh, I knew this was a mistake!” Twilight cried aloud, panicked about the state of her older sibling that she loved so much. Shaking her older brother, Twilight watched in shock as Shining’s thick endowment vulgarly smacked against his face in earnest, spurring on copious amounts of pre to leak out. “EW! Wake up Big Bro!”

A mumble rolled out of Shining’s throat as he unconsciously pawed at the air trying to silence the blustered pony disturbing his snooze. Twilight dodged her brother’s hoof, summoning a gold analog clock seemingly from the ether before forcing it into the colt’s face. Twilight quickly triggered the alarm, hopefully using it to snap her brother out of his daze.

It wasn’t very effective…

Still distressed, Twilight paced along the castle floor, filling the room with strained clops from her hooves. Her mind drifted for a spell, rummaging for an idea that could possibly get her brother to wake up. Fortunately for the purple alicorn, such an idea didn’t take too long to present itself. A mist concocted with swirls of regal shades of purple spewed from Twilight’s horn, the energy cycling inwards towards itself until it imploded, leaving behind the form of a megaphone. Perfect!

Screaming into the megaphone, “A MANTICORE TOOK MISSUS SMARTY PANTS! OH WON’T SOMEPONY SAVE HER?”

Twilight twirled around, her back facing her brother as she snickered at the brilliance of her scheme. It was a lie, a rather shoddily contrived one, but nonetheless was still a lie. A tiny portion of Twilight’s mind was unsettled towards the notion of abusing her affinity with her brother, but it was for the best.

The worn stone floor beneath Twilight’s hooves quaked, sending the mare several feet into the air. A deep thump echoed throughout the barren halls, flooding the air with a rumble that easily rivaled the audacity of a roar from an Ursa Major. Twilight gasped as she saw four oversized hooves attached to a rather normal looking (sans the enlarged cock) Shining Armor.

“What happened to you?!” Twilight’s voice shrilled in sheer surprise.

“What do you me-,” Shining’s inquiry trailed as he followed his sister’s gaze down towards his hooves. “WHAT IN CELESTIA’S NAME?”

Twilight carefully trotted over to her brother. Despite his appearance, they were still family. That said, she was still a teensy bit scared of his drastic change. Yet, her scholarly instincts took the better of her, urging the lavender princess to inspect this unusual sight.

Ducking and weaving between her brother’s legs, Twilight carefully scrutinized every bit of Shining’s newly sized hooves. Shining tried his best to keep a brave face, even though he was very clearly worried about his freakish mismatched appendages. Sure, he had just gotten his cock enlarged, but that was different. No pony other than Cadance (and he supposed Twilight as well) would ever have to see that. The mere size of his hooves were a completely unrelated topic of alarm. What would his wife say? What would happen if the princesses found out? He’d be a laughing stock forced to hide his appearance for the rest of his life. Beads of sweat formed from Shining’s furrowed brow, rolling down his shaking muzzle as his teeth clacked together anxiously.

“BBBFF, your hooves are almost three times the size of my head, it’s simply astronomical! I need to go get some parchment so I can take some notes!”

Before Shining Armor could get a word in edgewise, his younger sister had darted off, her love of science getting the better of her logic...again. Shining sighed mentally as he lowered his head. He had to remain tough; Twilight would be devastated if she knew how he felt. Shining’s mind surged, trying to figure out how he was going to break the news to his beloved wife. Knowing her, she’d likely get a giggle out of the entire thing. Cadance was good like that, always knowing how to bring clear, cascading light to an otherwise bleak situation.

Ow. When did his shoulder feel so tense? Not to mention sore, his body aching to stretch, to release the almost pleasant tenderness accumulating in his limbs. Why did he feel so...constricted? Must be a side effect from all the stored up anxiety. Opening his eyes, the colt noticed he wasn’t as close to the ground as he thought he was bef….

Holy haystacks I’m GROWING! Shining’s eyes bellowed, astonished and perplexed at his sudden change. And not only that, it didn’t look like he was stopping any time soon.

“Twilie!” Shining harked, surprised by his much deeper pitch, covering his mouth with his hooves as he slumped backward, causing the entire building to shake. Several decrepit bricks met their demise at the floor, pillars crumbling from the shockwave. Oh, erm, I need to be more careful~!

Shining winced as he felt his body stretch, his legs becoming thicker than Twilight’s tree house. “Neegh egack,” the royal captain let out a whiny, his torso growing much longer than before. His body wracked as his teeth tried to find purchase throughout the burning cramps. His lip quivered in earnest, rambunctiously rattling about like a foal with a new toy. “Unf Eaaaagghh! t-t-TWILIGHT!”

Every portion of the expanding colt burned like a trembling wildfire, eating away at the parched savanna grass with reckless ambition. His back cracked as the bones readjusted to his new seven foot size, his ears perked upward, surging with the stretching. Shining’s well-sculpted flank aggrandized outward, easily multiplying in size, giving his toned flank a slight jiggle as it grew, pushing countless amounts of bookcases to the ground. As painful as his expansion went, there was a minor tepid feeling of pleasure, slowly cascading over his body as he grew twice his normal size, surpassing eight feet-no, nine feet, before topping out at a whopping height of ten feet. Chest thumping from the aftershock of the intense growth, he sat in awe of his now larger frame, accompanied by his five foot shaft and alicorn sized balls. His sizable horn scraped against the ancient ceiling, threatening to collapse it should he move forward.

Suddenly the growing stopped. The pain had finally receded. His head was near ceiling level, as the poor stallion was forced to hunch over just to keep the castle from crumbling on top of him. The colt’s tongue lolled out of his maw, panting from such extreme changes. Droplets of saliva crashed to the castle floor below, creating an array of sizable puddles.

“Hey big brother I’m bac-Holy hayseeds! You’re HUGE!”

“Ye-yeah.” Shining moaned, still horribly out of breath. “Oh no...” an near inaudible groan tricked out. Shining wasn’t done growing just yet. His body rattled with intensity as his muscles tensed up, preparing to stretch again. Yet something felt different…

“Big brother, you gotta stop! If you keep at this rate, nothing will be left of the castle!”

An earth trembling wail came as a response to the tiny alicorn, “I-I can’t help it Twilight, I’m...I’m sorrryyyy~!” A cooling warmth wrapped the giant colt into a tantalizing euphoria. A spirit was circling every inch of the colt’s body, planting endearing kisses along his fur. The sheer fervor enthralled Shining Armor, causing the colt to break out into an exhilarated howl.

“AH!” Twilight yelled, quickly running towards the crumbling castle exit. It seemed like telling her brother to be careful was a bit of a lost cause at this point. It was a good thing nopony was in what used to be the reading room, now flattened by her brother’s quite sizable tail, of which looked better suited as the series of curtains in the royal throne room than a pony’s tail.

A deep resonate hum pierced through the air as Shining continued to grow, his testicles expanding and filling with new seed, causing cracks in the foundation beneath them as the massive orbs surged in size. Twilight just stared as she watched the form of her brother break free from the constraining space of the castle, the captain of the royal guard deeply grunting as his head broke free from the restraining ceiling as portions of the roof collapsed around his shoulders. Shining had broken past eighteen feet, his growth stimulating in ways the stallion could never had imagined. All the pain was simply whisked away by a monsoon of exotic exhilaration, drowning the stallion’s mind with overbearing erotic allurement.

Twilight was a mere speck, akin to the size of an ant to Shining Armor at this point, or at least he thought; his size was still quite off putting to his perspective. A cascade of deep moans escaped from his stretched throat, echoing among the forest around him. His lengthy legs looked more fitting on a teenage dragon than a grown male pony. Yet that wasn’t going to stop his growth any time soon. Teeth gritted, Shining held out against the pulsating inflammation, his body reeling for a rush of unprecedented pleasure. The stallion’s breathing quickened, lungs straining at the strenuous resistance Shining put forth. With a roar, Shining purged the apprehension seizing his body. The process was grueling, being so forcibly stretched as every molecule of his form expanded. Yet, an immense cascading pleasure wrecked Shining Armor, as every strand, every hair, every flake of skin broke out into a harmonious serenade of unadulterated comfort. The sudden change sent the colt into an inebriated state, as fuzzy green and red circles obscured his vision. His rapid breathing turned into that of desperate panting moans, shuddering with each dose of satisfaction, his teeth gritting in recoil.

A jet black object obstructed Shining’s view. Perplexed at whatever could be larger than him at this rate, the colt reached a hoof out, shocked as it grew wider than the foreign object trembling just inches away from his house-sized snout right before his eyes. Could this be a lingering tower of the castle? He gave it a small nudge, “WOooaaaaaaah,” Shining let out his loudest groan yet, the small tap routing throughout his body as it made a beeline for his nervous system, overloading the big colt’s senses. Just the small tap was enough to cause the stallion to edge on fainting right there, his brain finally putting together that his dong was as just as huge as he was.

His forehooves frotted up and down the thickening shaft of his floppy rod as it grew even further to attention. Precum dribbled out of the colt’s tip, pooling around his urethra before raining down, splashing all around his dear sister. His heart raced as rampant heat surged through his essence, pools of sweat the size of lakes running from his brow.

Twilight opened her mouth to reprimand her now giant brother when she caught a very unique scent wafting through the air. It was pungent, dirty, but extremely exotic...like the smell of a rainforest recently refreshed from a lengthy deluge. The smell tickled the inside of Twilight’s brain, beckoning the mare to give into her bestial desires. All strands of Twilight’s remaining logic receptors were quickly enraptured by the carnal haze, sending the poor alicorn into a deep realm of lustful need.

Twilight groaned, falling to her hooves, straining to overcome the intoxicating musk, but it was of no use, for her brother’s scent had already gotten the best of her. She felt streams of liquid trickle down the back of her hindlegs, her pussy quite wet from the abrupt erotic trigger taking over her very essence.

Shining, on the other hoof, was absolutely enthralled with his newfound size, fondling his colossal testicles as they glimmered from the copious amounts of precum slathered over the surface of them. The colt sucked on the head of his cock eagerly, lightly tugging at the supple tip. The nibbling was intense, the sensitive flare sending sparks of intoxicating zaps as Shining’s teeth very lightly combed over his own flesh. The taste was divine, a sort of gumdrop-like flavor doused in a sweet buttery sauce. Precum squirted from his tip, lining the roof of his mouth with the natural lubricant.

Truth be told, Shining had never experienced something this exotic before, but he knew that he didn’t want to stop. Convulsions suddenly wrecked the royal captain’s body, his form reaching its final growth spurt, as he exponentially expanded, his cock surging in length and girth, topping out at an enormous size of seventeen feet. The stallion felt a bit lightheaded, his frame readjusting to fit his gigantic stallionhood. Shining Armor let out a whiny as his enlargements finally came to a close. Sitting in a pile of crumbled stone and rock, the colt had maxed out at a whopping twenty-five feet, easily eight times bigger than the standard size of a stallion.

Inspecting his newfound size, Shining’s eyes trickled down to see a fairly tiny version of his sister ravaging her femslit with her hooves. Her brother’s masculine pheromones had quite clearly gotten the better of her, as a rather heated red tone was painted across her otherwise rich lavender complexion. The stallion cracked a smile almost a mile wide, glancing at his little sister carnally worshipping him.

“Hey!” Twilight gasped in between her feverish panting and strained breathing. Droplets of sweat ran down her face in a futile attempt to cool the horny alicorn. Shining was quite intrigued to see his little sister be so worked up over him, but being the benevolent stallion he was, he concluded that helping Twilie out was only fair. “What...What are you dooinnnngg~?!” Twilight’s voice trailed off as Shining twirled his sister around with his magic and licked his younger sibling’s flank, smearing the remnants of his precum over her rump. Her fur quickly bunched in through patches, clumped together from Shining’s saliva cocktail.

It was unexpected, but certainly not unwanted. Twilight pushed back against her brother’s colossal tongue, shivering as she felt his taste buds grind against her flesh. The mare was simply in heaven. Her wings stretched out wide as she felt the muscular tool caress her backside. It was then that Shining shuffled his approach up, cocking his tongue to the side to act like a giant dripping rod of lively muscle. Twilight nearly broke as Shining Armor ran his tongue along her curved rump, spreading her marehood open as his tongue shifted up and down between her hips. Twilight didn’t feel like a pony any longer; her mind diminished her status to that of a horny dog rubbing its butt against a wall, streetlamp, or just anything that would simply provide that touch to her nethers. Luckily, the gigantic tongue was doing just that, running the wet muscle along her slit, teasing the engorged and quite enthralled mound of feminine need with rumbling slurps.

Twilight’s flower bloomed wide as the invader pushed forward, spreading her fleshy petals ever further as her nectar flowed out of her slit. Shining stored up as much of his sister’s liquids as he could pool with his tongue, before retracting the gigantic muscle back into his mouth, sloshing Twilight’s sweet nectar. As Shining continued to toy with the tantalizing liquid, Twilight let out several desperate moans, her pussy spasming, reeling in the lingering pleasure left by her brother. She wanted him to tease her more, to play with her delicate parts; she wanted him. They were siblings, but Twilight was too far gone to care any longer. Knees trembling, the alicorn princess wailed as she felt his ministrations echo throughout her moist cavern. Why hadn’t he returned yet? She needed her brother. The intensity had ravished her body: her mane was aloof, feathers dangled outward, and her fur was tangled in several clumps, stuck together from her hulking brother’s saliva.

“S-s-shin-ing...please...more,” Twilight begged, her voice frail as her body was defenseless against her own orgasms. Still reveling in his sister’s delicious honey, Shining Armor let the delectable nectar coat the insides of his mouth before swallowing the sweet treat. Seeing his sister beg for his expert tongue work caused Shining to involuntarily spill several silos worth of precum down the length of his shaft, trickling down past his thick medial ring before coming to rest at his massive scrotum. His tongue jolted free from his maw, quickly going back to work on his sister’s moist vagina. Twilight squirmed as she felt the tip probe her delicate petals, slowly pushing forward. Unfortunately for the mare, there was no way she would be able to get much of her brother’s humongous oral muscle inside of her. Yet, that didn’t stop the female pony from grinding back on Shining’s tongue, as her body pleaded for it to go deeper. She wanted that foreign presence to spread her wide, to fill her body with its giant dripping mass. Twilight craved release; the sexual torment was too much for her.

Luckily, her big brother could easily sense that his sister was in dire need of an orgasm, so he decided to use some of Cadance’s favorite techniques. Using his tongue like a dildo, Shining began to rub his tongue between Twilight’s butt cheeks, simulating her like a teenage stallion furiously humping an inflatable “pleasure” doll. “AHH! Yes, please! More, I need more!” Twilight screamed, her pleasure on the edge. She pushed back towards her brother’s oversized tongue in a futile attempt to coax her brother to penetrate her ever so slightly, but his tongue was simply too big. Shining moved his treatment to towards Twilight’s right rear leg. In a flash, the colt quickly drew tongue up his sister’s leg, over her aching flanks and back down to the opposite leg. In response, Twilight seized up; her body was on fire. She could feel the flame burning with an intense white glow, running on magnitudes greater than Celestia’s sunlight. The heat threatened to incinerate her from the inside out, rolling through every ounce of her being like lava rushing down a volcano.

Her voice had gone raspy, vocal cords strained from being so close to the edge. “I’m so close! Please don’t stop!” Twilight’s vision fogged over, her eyes watering as if she was staring into an open bonfire, the heatwave baking her eyesight robbing her normally clear vision. Shining Armor knew exactly what he was doing, playing his little sister’s soaking cunt like a slide whistle, occasionally teasing her bulbous clit. A shrill scream detonated the coital haze, “AH! AH! SHINING I’M-AHH!!!” Twilight’s vagina clenched, her climax rolling like uncontrolled explosions demolishing a dam, destroying every ounce of resistance she had left. Her rational behavior was whisked away in the coming flood of orgasmic high, splattering what was several litres of her liquids onto her brother’s tongue, coaxing him to lap up the juices with more gusto than before. Waves crashed down her proverbial mountainside, uprooting every nerve like trees in a landslide as her climax rocked the alicorn’s body. Cum poured into Shining’s tongue which he tried to shape into that of a dipper, hoping to pool as much as his sister’s fluids as possible. The liquid he couldn’t catch was splattered around the inside of Twilight’s lengthy rear legs.

Wait. That can’t be right...Twilight’s mind instantly jolted, temporarily pulling her out of her orgasmic state. In her euphoric daze, she had forgotten that spells from the elder days had a chance to linger for several hours and could be sporadically recasted if the proper decast preparations were not followed. Uh-oh. Her body was powerless to stop her continuing orgasm, her mind trapped in a state of uncontrollable casting. Twilight’s being ravaged to regain command, feeling herself getting weaker as her climax continued, her body colluding against her. Her eyes lazily rolled upward, her horn already glaring with magical energy. It was only a matter of time before the spell would come to form again.

I’ve got to fight ba-ah!

Plop! Shining had moved to more unconventional means of spoiling his sister, slapping his tongue against her still oozing flower, pillaging the marecum from Twilight’s nethers. At this point, it was too late for the alicorn. The spell had already taken shape, growing her body at an accelerated rate. And against the princess’s wishes, the burning already demolishing her husk swiftly rekindled, the flame growing even stronger than before as her frame enlarged instantaneously, accelerated by the passion she was being subjected to.

The process was rather painless, though that could easily be attributed to her subsiding orgasm having already overloaded every nerve in her being. And while her body was coming down from the coital high, her brother still continued to work his tongue around her vagina, now being able to push it in further thanks to her expanding size. In fact, Shining really didn’t seem to mind his sister now growing larger, shoving his tongue into her snatch, using only the tip to tease her drenched canals. In mere seconds, Twilight had nearly caught up with the size of her brother, spanning at a height of twenty feet. Satisfied that he had eaten out all that Twilight had to offer, Shining withdrew his tongue, exhilarated from the intimate moment he had just shared with his younger sister.

“Oh Shining that was amazing~” Twilight moaned as she turned to face her brother, her cheeks still flustered. Having obtained dominance over her body, Twilight could see that Shining hadn’t been able to get off yet and she felt a deep pang in her stomach, like it was only right to return the favor. Shining was standing at full attention, his cock painfully hard, a trait that Twilight thankfully picked up on. His stallionhood just stood there, a prime display of seventeen feet of bestial beauty, as veins pulsated with the colt’s heartbeat. It was slick black, coated in several volumes of precum that continued to pour out of the tip. Twilight’s gaze dangled further, painting over her brother’s thick medial ring that separated the raw stallion gland with a smoother patch of skin that made up his sheath. Her eyes came to a full stop at the two obscenely large orbs that rested below his shaft, full of Shining Armor’s seed. The entire package was a tantalizing display of male prowess that only accented his muscular body and handsome fur coat. The image in front of the young alicorn was so inviting...Twilight almost felt a need for it. Twilight pushed her brother backward, causing him to land on his back and demolish what was left of the first floor of the aging castle grounds. The sound of bricks snapping like branches perked up as his twenty-five foot frame bore down on them.

“Uh Twilie, what are you doing?”

But before Shining was given the benefit of a response, Twilight pounced upon his stallionhood, rubbing herself along Shining’s massive cock. “Ooooh,” Shining cooed as his sister glided against his lubricated shaft. The younger pony wrapped her hooves around the massive girth which felt like half the size of her body, pistoning her frame like a hoof against the penis.

“Shining, you’re so big~,” Twilight gasped as she continued to work, her belly stained with her brother’s pre. She humped the length, tapping into her visceral behaviors, clutching Shining’s cock harder, feeling it throb in delighted response. “Oh yes, you could positively wreck me, big brother,” squeezing the penile flesh like a newborn to a teddy bear.

Shining was lost in the slew of attention being given to his endowment multiplied only by the fact that it was his little sister working her body along his gigantic girth. As if by instinct, the gargantuan colt thrusted against his sister, his penis grinding against her smooth fur coat, using her like a living cock sock. Shocked, Twilight gasped as she felt her brother work against her ministrations. Using her lolled tongue, the velvet alicorn licked along the ample flesh, dragging it along the many ridges of Shining’s accented veins.

“Twilie, oh...please...don’t stop~”

Grinning like a madmare, Twilight focused on working her way to the tip, watching the flare burst outward like a cannon. Opening her mouth, Twilight eclipsed the head of her brother’s stallionhood, poised like a lioness ready to strike.

“Shining? Is that you?” a voice called out from behind the siblings. The two ponies froze, almost petrified by the sound of what could only be Princess Cadance. Twilight slowly removed herself from her brother’s massive erection, which still dripped in a fervent display of precum, mottling his pure white coat in much darker patches of gray. An extremely embarrassed Twilight Sparkle tried to hide her face in her hooves, causing the earth to tremble from her folly. To be caught in such a predicament in front of her old foalsitter was too much for Twilight to bear.

“Uh hey Cadance,” Shining boomed, forgetting that his voice had been amplified with his size, uprooting a few trees in the distance. He anxiously rubbed a hoof behind his neck, sporting a very obvious “please don’t kill me dear” smile. “How did you find us?”

“Well when you didn’t show up at the train station, I assumed you would be at Twilight’s. Yet when I got there, Spike told me that she was at Celestia’s old castle. Or at least what looks like the remnants of it.”

“Oh...yeah...oops,” Shining replied. It was his turn to let out a rather embarrassed blush.

“Now judging based on what was happening before you two so rudely stopped, I’d assume that this was a part of our anniversary?”

“Uh not exactly…,” Shining began to explain, telling his wife about the spell and the mishaps and how that made the both of them gigantic. Twilight just sat a few feet over from her brother, face buried in her hooves, occasionally nodding in agreement.

“Shiney, you did all of that just for me?” Cadance let out a giggle. She was good at rolling with the punches, and in addition to being the sexiest mare in all of Equestria, she loved all displays of love...even some of the taboo ones. “You’re so sweet honey, and you really know how to make a girl feel really inflamed,” her words were soaked with lust. “Besides, such special times are better shared with the ones closest to you.”

“So, you’re not mad?” Twilight asked her foalsitter, her demeanor regarding that of a sad puppy being told that they would be getting a treat.

“Nope, but I would really like to get in on this action,” Cadance replied, looking up at the towering ponies beside her.

“Ooooh! I love you so much Cadance! You’re the best sister-in-law a mare could ever ask for!” Twilight practically leaped up into the air, bouncing on her hooves, almost forgetting the fact that she needed to be more careful about her size. Chunks of rock flew out around her hooves as she landed with glee.

“Twilight, please be more careful!”

“Oh, right...sorry!” Twilight bashfully responded. Bringing her head down towards her old foalsitter, Twilight gave the pink alicorn a mighty lick, obliterating Cadance’s previously dry fur with saliva. Cadance gave Twilight’s huge muzzle a tiny nuzzle in response, returning her love for her husband’s sister.

“Now, I think it’s only fair that I gain an advantage in all of this as well,” Cadance mentioned, wrapping herself in a ball of ferocious white glazed light. Much to Twilight and Shining’s awe, the ball rapidly grew bigger, before fading away as quick as it came.

“How...how did you do that so fast?”

“Twilight, that’s the correct way to perform the spell. Surely you’ve read Starswirl the Bearded’s book on Molecular Reassembly volume seven, right?”

Twilight was dumbfounded. “There’s a volume SEVEN?!?!”

Cadance could only let out a giggle at Twilight’s bewilderment. “I’ll let you borrow it later~,” she said with a blissful tone.

Meanwhile, Shining was left dumbstruck at his wife’s new size. It was as if every curve, feather, and hoof were crafted by the gods. Granted, Cadance was always drop dead gorgeous, but the new twenty-three foot tall Cadance was just too much for his eyes. Luckily, his brain was able to drive on instinct, bringing his boner back to life as it surged with blood.

“Twilight dear, will you help me with your brother?”

No words were needed to be said as Twilight raced over to one side of her gigantic older brother. She watched as Cadance sat down next to Shining Armor and began to rub her soft hoof along the massive cock. Shining groaned in response, revelling in the smooth texture of his wife’s tender hooves. Twilight mirrored her action, rubbing the vibrant horsecock while she used her magic to fondle her brother’s massive balls.

“That feels great Twilie~,” Shining moaned as the magical aura enveloped his testicles. Cadance grinned at Twilight, forming a rather naughty idea in her mind. Twilight had now moved towards licking the giant stallionhood in addition to rubbing the taut penile flesh with her silky hooves fit for the princess she was.

Making sure that Twilight wasn’t paying attention, Cadance quickly formed a spell around the purple alicorn, causing her to be lifted by her massive, curvaceous rump and dragged such that her body was hovering over Shining Armor’s cock. Twilight was too lost in her lustful actions, never once ceasing her incestous ministrations. Cadance spread the younger pony’s legs wide, settling Twilight into a straddling position much like the one she had found her in earlier.

With a tiny chuckle, Cadance dropped her mammoth sized sister-in-law onto her husband, who let out a pleasurable roar, sending animal critters within a five mile radius running for shelter. His cock surged from the sudden pressure, revelling in Twilight’s soft lavender fur as each tiny bristle teased the engorged veins along his shaft. She was as soft as her palpable marehood was velvety. The young librarian bucked her hips forward, resuming her previously interrupted thumping, her crotch jerking against her brother’s regal cock.

“Twilight, I'd never thought you would be this adorable riding your brother's thick cock,” Cadance cooed, watching to the side as her slit leaked out gallons of her aroused juices onto the canopies of the forest beside her. A hoof traveled down to her nethers, mindlessly teasing her protuberant clit. Her body slowly awakened to the resonate heat of the group’s arousal, lost in the wafting blend of sensual musks lingering in the atmosphere. Cadance took a whiff of the rousing pheromones, letting her psyche be assaulted by the carnal pleasure drifting amongst her.

Twilight shifted backward as she humped her big brother’s seventeen feet of male prowess, rocking her hips with every return, her enormous plot wobbling at the peak of her thrusting, pussy extremely aroused by her brother’s dashing sexuality. Cadance could only smirk at Twilight’s inadept notions to please Shining, but she couldn’t argue with the results; her husband was lost in the furrows of sensual stimulation, his head shift from side to side, leaving giant imprints of his face in the forest surrounding the area. In the several years she had known Shining Armor, she became aware of his habit of kicking during intercourse. Cadance found it adorable, even more so when she saw his twelve foot long hooves restlessly plowing through the already agitated air, forming large gusts of wind.

A tinge pulled Cadance out of her tangent, reminding her that she too was horny from the entire ordeal and pined for release. Yet Twilight was busy with her brother’s endowments, there really wasn’t anything that she could… Cadance’s mind wandered for a spell. Had Twilight’s rump been that cute all this time? It looked so...squeezable...so inviting. The princess of love hadn’t had the chance to see Twilight’s body in this much detail before. The way her flanks jiggled on each thrust, the smooth curves, the accented hips…and the way her flower gasped as she pushed down on Shining’s cock...it was almost divine. Fitting for a goddess, Cadance thought, she’ll be an astonishing princess. She had to touch it. It was too desirable not too, she knew how Twilight felt from a formal stance, but she never had actually felt Twilight before, and now she had the chance to become better acquainted.

Lightly gliding on her hooves, Cadance worked her way to her sister-in-law’s behind, trying to be as subtle as possible, though her large size made the task quite the challenge, as the plains of Equestria rumbled in resonance with her hoofsteps. Peering over her husband’s crotch, Cadance inspected the deep purple mounds adorned with Twilight’s magical cutiemark. Being so close to her prize, Cadance couldn’t resist but to scoop Twilight’s curvaceous cheeks and fondle them like she did with her husband’s cum pouch. But she didn’t want to ruin the loving moment played out in front of her.

Yet, being the princess of love came with benefits, like the ability to change certain parts of your form as the situation called for, or being able to infuse pleasure for “better” purposes. Granted, most situations were encountered in the royal bedroom, the royal shower, kitchen, basement, library and pretty much anywhere else Cadance was able to score with her husband. Despite being royalty, Cadance really did have a rather devious streak.

A streak that brought a devilish grin to the mare’s lips. In a flash, she recited a spell she learned when she was just a teenage pony, making trips to Celestia’s private library way past her curfew. She had wanted to use spell with Shining, but she never felt like she had found the opportune time. However, there was no way she was going to pass up such an adorable orgy like the one before her eyes.

Cadance’s crotch swelled outward as a bulge formed from the flesh underneath her lush folds. Soon enough, a rippling appendage took shape, blasting outward past the alicorn’s chin with a size rivaling the width of her body. Her cock wobbled, as blood surged through her new phallus, the raw penile flesh thickening as it filled with her arousal, the tip smacking against her petite chest with a plop. At the end of her penis hung a scrotum with a set of testicles the size of wrecking balls, loudly churning as they filled with her seed.

Twilight’s massive body was like a narcotic to Shining Armor as she rocked against his massive endowment. His mind fizzled, completely wrecked from just the simple reasoning that he was performing such a taboo action with his little sister. Sure she was doing most of the dirty work, but he was letting her. Shining’s teeth bit down on his lower lip, hoping that he could just edge a bit more. He wanted to hold out until his sister had reached her breaking point.

Cadance, however, opted for a more direct approach, reaching a hoof to Twilight’s head as she bucked against her brother. With a raspy groan, Cadance pushed her new endowments straight into Twilight’s perky plothole, forcing the puckered entrance wide. Twilight’s head reeled upward, only to be forced down into her brother’s flesh. Cadance was going to rut the young princess to oblivion, a notion she made clear with a rocky growl, her teeth clenching for emphasis.

Twilight opened her mouth to inquire what her former foalsitter was doing, but only a weak moan came forth. Her brain was too lost in the sudden penetration to formalize any sort of words. Cadance pressed forward, her dong stretching Twilight’s anus wide as it burrowed deeper into her nethers. The passage was tight, restricting and rather painful, squeezing the princess’s penis to the point it felt as if it would burst. But the sheer pressure was more than enough for Cadance, as she felt Twilight’s muscles constrict along her length, touching every inch of her dong. Gritting her teeth, Cadance pulled back, letting the flare of her head drag through the purple alicorn’s clenching anal cavity. The princess of love’s body shriveled from the narrowing passage, clamping onto every vein of her shaft. It took every ounce of Cadance’s power to resist collapsing onto Shining’s sister, escalating Cadance’s sexual drive. Gallons of precum lurched out of the oversized penis, lubricating Twilight’s dusky passage. “Uuungh!” Cadance grunted as she thrust her hips forward, plowing her cock into Twilight.

“OHhhhhh,” Twilight moaned, the foreign object in her ass rubbing so erotically against her walls. Cadance staggered forward a couple feet as the intense friction sent a hurling inferno up her cock. Twilight’s heart raced; she’d never tried such penetration before, and to have her face forced into her brother’s cock while his wife rutted her passage was simply intoxicating. Cadance could feel every pump of Twilight’s heightened heart rate, she could feel inside her as the lavender princess continued to hump her brother’s bothered cock.

With every buck forward, Cadance pushed Twilight further up Shining’s cock, causing the stallion to hump backward, sending Twilight back onto Cadance’s thick pole. The vicious cycle continued as the three fucked each other damn near well senseless. Shining bellowed as Twilight was rammed into his stallionhood by his wife, pressing his awfully bothered endowment to his muscular chest, drenching his fur in lake sized splurts of precum. His neck was doused in the sweet lubricant, cooling his burning complexion from all the intense fucking the ponies had been through so far.

Plop!

Shining eased his head forward, only to find his little sister planting eloquent pecks of endearment around his shaft. The suction filling the air with consequential plops, her lips dragging along the length until he felt a wet prod…

Sluuuuuurp!~

Licking his shaft, Twilight painted her brother’s bludgeoning stallionhood in lavish amounts of her saliva, tiny moans echoed pasting her lips with every thrust from Cadance’s cock. She went along her task with immense gusto, like a filly enjoying a chilled treat on a humid summer day. Just as Shining Armor relaxed his head backward, he let out a small yelp as plumes of heated vapors tantalized his overly sensitive penile flesh. His tongue lolled outwards, dangling to the right of his mouth like a dog enjoying the wind rushing past its face. Twilight had kicked up her actions, sucking the tip of Shining’s massive erection. Unfortunately for Twilight, there was no way she could fit the entire girth of her brother’s rod into her mouth; his arousal had charged his colossal flare that it was easily bigger than Twilight’s maw. But that didn’t stop the young librarian from giving it her all as she hunched her neck forward, allowing her to assault her brother’s urethra with her throbbing pink oral muscle. Twilight swirled her tongue along the circumference of her brother’s tip, occasionally lapping at the hole.

Twilight wailed as Cadance continued to rut Twilight’s abused anus, sending lustful soundwaves of pleasure down Shining Armor’s stallionhood, vibrating as the volume grew higher as his sister approached her release. Shining felt his balls churn with desperation, begging to be emptied, to let all that pent up cum flow free. Temptation jittered through his testicles up towards his sex-rattled brain. But despite the rousing feeling of instant release, Shining remained firm, holding out against the rapid flow of jolting nerves begging him to climax. Lip trembling, hooves quaking from his impending release as they tore through the terrain, desperate to find purchase amidst his longing fervor. His precum production increased tenfold, pouring out at the rate of a roaring river, practically feeding Twilight a hearty amount of his liquids.

“I’m...I’m going to cum!” wailed Shining Armor, edging for a few more precious seconds before he was about to burst.

The announcement sent Twilight spiraling, letting a resounding purr roll from her throat, the resonant waves echoing down Shining’s length. Cadance bucked forward, pressing her medial ring to Twilight’s anus before it broke forward with a vulgar plop. Tiny thrusts pressed against Twilight’s opening, with over half of Cadance’s length buried inside of the young princess. With an extremely harsh groan, Cadance bit her lip, before ramming herself to the hilt inside Twilight. Twilight let out a muffled scream that could be heard all the way in Canterlot as her inner walls convulsed around the massive dong resting inside her.

The feelings were too much for Twilight Sparkle, her body coiling like a taut spring as she came, breaking the seal around her brother’s cock as her head cocked backward, spraying her juices onto the two elder ponies. Her honeypot spewed the sweet nectar, coating the two sets of testicles behind her as well as the majority of her brother’s rumbling erection.

Cadance didn’t let Twilight’s climax stop her, as she continued to buck forward, drowning in the intoxicating wails of the mare’s orgasm. Twilight’s moans filled the sky like a chorus of angels, beckoning from the sensual depths of her very being. Her voice sang out like a hymn, filling the ears of those in the vicinity, sending waves of bliss down the recipient's spine. Cadance simply melted as she felt Twilight express her unadulterated joy, and with a final thrust, unloaded her sperm into the younger alicorn princess, swelling the pony with the sheer volume of her load.

Upon Cadance’s last thrust, her swinging testicles came crashing into her husband’s providing the final push against Shining Armor’s resistance, as his balls were nuzzled by Cadance’s draining sperm banks. “Ooooh buck~,” Shining let out a deep groan as cum rushed up his cock, ready to fire from his massive masculine cannon. Twilight shook as she felt her brother’s cum surge through his cock, unready for the what was soon to follow.

A massive explosion rattled in all occupants within the nearest four mile vicinity as Shining’s cum blasted out of his penis, flying at a speed upwards of mach five, instantly obliterating the sound barrier with his ejaculation as his cum shot past distances of two miles, annihilating the surrounding foliage. Cum flew past the giant male’s muzzle, landing in a the form of a grand lake, his sperm drowning the terrain. Spews of semen cascaded through the air as his cock splurged out more of his seed. Shining rode out his orgasm, watching his white hot cum grace the sky like the southern lights. Twilight collapsed on top of his cock, her nethers still leaking the remnants of her orgasm, belly bulging outward from Cadance’s continued climax.

Words slurred out of Shining’s mouth, as his sensually perforated brain struggled to make sense of the events that had taken place.

Twilight’s stomach gurgled loudly pushing outward as Cadance gave her fellow princess a stomach that rivaled the size of a mountain, pushing out longer and longer as the rest of Cadance’s climax spurged forth. The passed out purple princess’s previously taut stomach grew ever thicker as the skin stretched outward to accommodate the last few splurts of Cadance’s orgasm, surging outward until it bubbled around her brother. The two remaining ponies panted, their heated breath evaporating before them.

“We...we gotta do this again some time..,” an exhausted Shining Armor whimpered.

“There’s always next year,” Cadance proclaimed with a wink, settling on top of the bloated Twilight Sparkle, her cock still hilted in the mare.

The three of them rode out their afterglow in the realm of dreams.

Author's Note

Seriously, sudden inspiration hit me and I couldn't let the idea go to waste. Tummy Wubs is still on schedule for being next. :3