Find Out and Fuck Around

by EpicGamer10075

Rating: mature
Tags: Twilight Sparkle, Anthro, My Little Pony: Friendship is Magic, Porn, Sex, Spike
Length: 5825

Twilight accidentally gives herself a cock when trying to cure her heat, and now her dummy thicc brother Spike wants to help her deal with it.

When helping Twilight make a potion to deal with her heat, her dummy thicc brother Spike accidentally messes something up, and the potion ends up doing something that makes Twilight’s heat even more difficult to ignore.

Spike, of course, can’t stop himself from getting a taste of the new stallionhood between her legs, and ends up getting a lot more than a taste in the long run.

Cover Art: 2442328 on Derpibooru

Futa!Twilight x Femboy!Spike clopfic, commissioned by anonymous

Kinks:

Incest

Futa

Fem-to-Futa Genderswap

Semi-Hyper Cock/Balls

Dummy Thicc Femboy

Deepthroat

Anal

*Featured on 14/08/2023

Published 2023-08-14 03:50:00 UTC
Last updated 2023-08-14 03:50:00 UTC

Working not as Intended

Twilight looked across the list in her hands, noting each element on it despite having already burned them into her mind, all done in attempt to distract herself from this plague that she was attempting to cure in the first place. Her good, alchemically knowledgable friend Zecora had written up this ingredients list for her in her elegant, yet a bit scrawly handwriting so that Twilight could make this potion whenever needed in case she couldn’t get it made by Zecora herself.

She had already dealt with the unfortunate consequences of that before, with even a single day of dealing with this problem feeling like a slow, torturous poison, hardly able to focus on anything but the hot, sweaty bodies of other ponies in the Summer heat. That heat that drove her mad had cut off weeks of her life with agonizing lewdness before she talked with Zecora about it, and while she was very thankful about the help, she still knew it would be quite a pain to deal with thinking about that Zebra’s firm, muscled body…

“Twilight, what’s next?” A youthful, innocent voice asked, cutting Twilight’s depraved thoughts off for just a moment as she looked over to her cute little Dragon brother, Spike, but she couldn’t stop herself from admiring the visual buffet of his big bubble butt, clad in tiny booty shorts that let so many of its shiny purple scales gleam in the eerie green lighting from the glowing cauldron in the middle of the basement laboratory. “Twilight?” Spike repeated as he looked over his shoulder at the Unicorn, trying and get his sister’s once again wandering attention away from his rear.

“R-right, um,” Twilight stuttered in embarrassment as she wrenched her gaze off that delectable Dragon cake and back towards her list, and read through the ingredients once again, their memory in her mind fuzzy and filled with gaps, so she had to repeat the next ingredient from it, “27 milliliters of rose nectar.”

Spike quickly went over to the large area of cupboards and drawers that contained most alchemical ingredients one would ever need, and opened the drawer with the flower label, sifted through the bottles of petals and stems before getting to the nectars, and then pulled out the rose one. Closing the drawer and carefully opening the bottle of nectar, he slowly poured it into a graduated cylinder until it about hit the 25 ml mark, and let a few more drips of the stuff pour in until it landed on 27. Closing the bottle back up and stowing on the table alongside the other used ingredients, he moved back over to the cauldron and poured the nectar in, then picked up the large wooden stirring spoon in it and started stirring the increasingly potent-smelling mixture within it.

Twilight, while slightly annoyed at the almost haphazard layout of ingredients left on the table, was still more focused on her heat and just wanted to get rid of it as soon as possible. However, she could tell Spike wasn’t quite as serious about it, as he kept teetering playfully on his paws while leaning over the glowing brew in the cauldron, his fat butt wobbling and jiggling up and down ever so slightly with his every movement. His legs were just far enough apart that she could see a small bulge in his shorts between his thick thighs, and she followed its every swaying motion with her eyes, knowing from some previous unfortunate incidents exactly how dainty and cute it was, and how it was often rather pent-up and able to cum more than she’d imagine.

Twilight’s breathing was already rather hastened by her heat, but the sight of that large ass, so plush and soft you could easily use it as a full-on pillow, and that delicious little package, musky and sensitive enough to enthrall her for hours... She started to sweat from more than just the humidity the cauldron was giving off.

Shaking herself as she tried once again not to fall victim to her bubbling lust, Twilight looked back to her list and muttered out, “A-alright, next ingredient...” She started to trace down the previous ingredients already put in, but about halfway down, she heard a somewhat quiet ‘ding-dong’ from the floor above. “Oh, shoot, that’s the door,” She commented as she pulled her eyes off the list, but then turned them to her bottom-heavy assistant and said, “I-I’ll get that. Um, h-here,” She ended up stuttering at the end as she thought of the list in her magic, and then tossed it over to Spike, who quickly caught it in his grasp as his sister turned tail and headed towards the stairs of the basement and went up them to get whoever was at the door.

“Alright then...” Spike said to the open air as he looked down at the list now in his own hands, and while he did find the text a bit hard to read, he still decided it would be fine to add a couple more ingredients while Twilight was away. She did trust him, and certainly seemed adamant about needing him to be here for this, after all.

Reading down the list, he soon found the next ingredient to be added, but he couldn’t quite make what it was supposed to be, mostly partially due to the obtuse handwriting. He could tell there was multiple words, and one of them was likely a quantity, so he interpreted what seemed to be ‘vail af whol res’ as ‘vial of horse’, and thankfully he knew that Twilight happened to have some patches of fur from many different species somewhere.

Looking over at the cupboards, Spike soon spotted one of them labeled with ‘Other Species Material’, and swiftly opened it, having stand on the tips of his paws to better access the stuff inside, and carefully pulled out a few bottles filled with different colours of chopped up fur or scales, reading them one after another before putting them away when they weren’t labeled as ‘Horse’. Eventually, though, he did find it, and then closed the cupboard before locating an empty vial resting on the table he put the rest of the used materials on, and opened the bottle of Horse fur to fill the vial up with it before closing the bottle back up and setting it aside, then finally going back over to the cauldron to dump the ‘vial of horse’ inside.

Setting the vial back on the table, he got back to stirring the mess of stuff inside the cauldron, which seemed to noticeably change colour as the fur got mixed with the rest of the ingredients, and Spike figured they were making progress! His hearing perked up soon enough as quiet ‘thumps’ came back down the staircase to the main floor, and he then spotted Twilight coming down to the floor below.

“What’s that?” He asked of her as he noted the piece of paper in her hand.

“J-just a weather check...” Twilight replied, seemingly oddly tense as she looked back at him. “Derpy was late, a-and there’s heavy rain coming in a few hours.”

Nodding in understanding, Spike smirked and retorted, “Well, it’s good we can make this potion now; Zecora would have a heck of a time getting here in that weather!”

“Yes, of course...” Twilight trailed off with a forced smile, trying to keep her eyes away from her brother’s lower half, the connotations of being locked inside with him weighing very heavy on her mind.

“Oh, by the way,” The Dragon added as he trotted over to her, forcing her eyes to fight harder to keep away from those thick thighs while they approached her, and more towards the list in his hand as he held it out for her. “I did put the next ingredient in.”

Twilight sighed heavily and spoke down at him, sounding somewhat tired and admonishing, “Spike...”

“What?” Spike retorted, shrugging his shoulders casually, “Might as well, right? You’ve already forced me to add the rest of these, so this one ain’t a big deal.”

Rolling her eyes in beleaguered annoyance, Twilight quickly darted her eyes away from her rear-heavy brother as he turned around to head back over to the drawers and cupboards, and she looked back down at the list in her hands, mentally crossing off the ‘vanilla leaf (2 whole leaves)’ that was supposedly just added, hoping that Spike got the ingredient right.

The potion didn’t seem to be working properly.

Twilight was writhing under the covers in her bed, huffing and moaning out into the slightly musky air, her heat coming at her full force despite the steps she took to stop it. She knew the potion she made took some time to properly take affect, but it shouldn’t have taken this long... Of course, maybe that one ingredient was wrong due to Spike’s eagerness, but...

“Ooo-oh!” She moaned out loudly from the thought her adorably sexy brother, his big fat ass and pent-up nuts unable to leave her thoughts while her body was flooded with heat, her hips jerking up from the unrestrainable desire to have her face stuffed into all of that. “Unnnngh!”

She was left shivering in lust, smothered in her own heat under her blanket with her thoughts utterly locked onto Spike’s assets. Twilight could feel her nether region getting so hot and wet from those thoughts alone, and it felt so maddeningly sensitive to any slight brushing against it, even more than she’d ever dealt with in the past. Maybe she was just getting older and her hormones were developing more, maybe it was the potion backfiring, or maybe it was due to how odd her genitals felt at that moment, with the impossible sensation of weight to them, like her bits were wobbling around somehow.

“Gggnnh!!” She suddenly moaned out as another sensation took hold of her crotch, its being inconceivably surrounded by a hot, wet tightness that constricted and squeezed her genitals, making her hips jerk upward again towards whatever was doing that to her. She could start to feel something grazing against the inside of her thighs as well, multiple sharp points tracing down her legs as the tightness enveloped more and more of her naughty bits, and she was beginning to feel some faint tension in her loins, with the ensuing orgasm ever-present as a possibility in her mind.

No matter how much Twilight tried to ignore it, pass all of it off as just her lust getting the better of her subconscious, she couldn’t stop that building tension, nor the confusing sensations around her crotch, with its size and weird... stiffness, if she could call it anything, as well as the wetness and warmth that surrounded it, driving her further into rapture.

Opening her eyes sharply, she decided to see what was up, hopefully just figuring out that nothing was actually happening to her, and calm herself enough to get at least a level of sleep. Deciding to do it, though, was just the first step, and the way her body felt so hot and tense, forced her back into the mattress at the first attempt to rise out of it. Taking a deep breath--or, at least as much as she could of one with the lust burning through her body, she shoved herself up into a sitting position, and grabbed the blanket on top of her with both of her hands, then threw it forward off the bed, revealing...

“SPIKE?!” Twilight shouted in bewilderment as she stared at the younger Dragon, his face nestled between his sister’s thighs, eyes looking back up at her, but clearly unable to actually see her with how wide they were blown and the utter rapture on his face. Her adrenaline at the shock of it all kept her mind just sane enough for just long enough to notice Spike’s maw was wide open, something thick and purple stuffed inside...

It was only for a moment that she could grasp what had happened to her with a (relatively) clear mind, as her lust then kicked back into her mind, and she fell back onto her bed with the tension in her loins at a peak, and she came.

The new stallionhood swelling out between Twilight’s legs twitched and throbbed within Spike’s tight and wet throat, her balls clenching madly below his face as cum surged out of them and through her shaft, splurting down into Spike’s stomach and filling it with a full warmth that the Dragon couldn’t help but bring a palm down to press against his belly to feel. Twilight’s hips kept jerking up repeatedly and forcing her cock to bob up and down in his maw, the unicorn’s mind so flooded with lust that the moans she let loose were practically screams of ecstasy, crying out into the open air as the sensations of her new set of genitals utterly overwhelming any sense of decency or embarrassment that’d usually quiet her down when orgasming.

The two could hardly process anything but the incredible amount of cum flooding into Spike’s body, there being simply so much of the stuff that it couldn’t all flow down into his stomach, and some of it was forced to work its way back up through his throat around Twilight’s cock, and all the way out through his stuffed maw and open nose, spurting out messily and splattering and gunking up patches of lavender fur on Twilight’s crotch. All of that cum flowing through Spike’s throat was making him start to gag, and while he did remain there for a moment to soak in the delicious pain that his throat getting so stuffed caused him, it did eventually get the better of him and forced him to slowly try and pull his maw off his sister’s dick, perhaps thinking he could let the cum splatter all over his face and lick it off...

But Twilight had other plans. Acting purely on feral instinct as she continued to get drowned in pleasure from her orgasm, she reached for Spike’s head with both her hands and yanked him down onto her cock, stuffing it deeper down into her throat than before, and in fact forcing him to swallow the entire length of her massive meaty monolith. He gagged harder and more often as he was completely unable to breathe under the volume of the stuff shoved into his maw, trying to use his claws to push off Twilight’s thighs to get away, but his pain made him far too weak, and he was left to struggle and gag on more cum as it continued to flood his stomach.

Luckily, though, it all didn’t last too much longer, as all the pent-up seed in Twilight’s weighty nuts soon got evacuated into Spike’s belly, shrinking the former just a tad while the latter was inflated enough to give him a quite noticeable pudge. Her grip on his head then weakened to the point where he could actually pull himself away, slowly retreating the cock from his overstuffed maw and letting tons of cum and slobber drench the shaft on his way out. Eventually, he finally did break free of the cock, it popping out of his mouth with a wet shlrrrp before he fell down onto the bed, face down as he heaved deep breathes to try and regain his lost air from between his big sister’s thighs, nasty fluids getting dribbled down onto the back of his head from Twilight’s cock that still wobbled about above him.

He couldn’t tell how long he was there for, just breathing heavily and letting his sore throat rest, before Twilight moved from her position, wearily sitting up, and unintentionally letting her cock flop down onto the back of Spike’s head. “O-oh,” Twilight started, her exclamation of surprise and guilt turning into a lustful moan as she tenderly grasped her still partially erect meat stick and pulled its slimy mass off her little brother’s head, setting it off onto her thigh with another tender ‘mmf...’ before finally pulling up Spike from between her legs by his shoulders.

“A-are you alright..?” She asked weakly of him, looking back into his listless and unseeing eyes, the aftereffects of drowning him in cum clearly still not done with. That was hardly the case on the surface either, she noted as she saw the cum dripping out of his nose and drooling out of his half-gaping maw, and both streams of it trailing down his face and continuing down his chest where most it was finally finished in its smearing against the bed.

“S-Spike?” Twilight tried again, concern clear in her voice as she stared into her brother’s face, her arms wrapped around his shoulders and shaking him lightly, and she could slowly see some attention come back into his eyes before his mouth closed back up, involuntarily licking off the cum that remained slathered across his lips. “Are you okay...?”

Spike took a deep breath as his eyes refocused, looking somewhat lost for just a moment before they turned upward to meet his sister’s own gaze, but it was only for a moment, as they then swiftly went back down to look at that new horsecock between Twilight’s legs. His sight was clearly affixed by that thing, his nostrils flaring and his breathing picking up again to sniff and inhale all the musk he could off of that delicious purple cock.

“Spi--”

“Fuck me,” The Dragon cut her off, his voice a breathy, needy growl as his were kept unmoving from his new fascination.

“W...what..?” Twilight sputtered weakly in response, struggling to keep her grip up on Spike’s form while his arms slowly rose up from laying on the bed to approach and slowly stroke the semi-erect shaft, making its owner flinch back in surprise and shock. “W-why are you...” She tried hopelessly, unable to figure out exactly what she wanted to ask, but at least knew she was very concerned about this... filthy and unsettling behaviour.

Spike didn’t even look back up at his sister as he continued to stroke almost reverentially at her cock, but did eventually speak to her in a breathy, somewhat whimpering tone, “You’re in h-heat, right..? T-this will deal with.. that....”

“W-well, maybe, but--” Twilight tried again, but was cut off once more by her lustful brother.

“J-just fuck my ass already.. s-sis...” He whimpered the last word out, but the way his breath picked up further after saying it made it clear just how turned on he was getting by such a lewd and taboo idea.

Twilight was hardly unaffected either, as she was left shivering in lust from not only the continued stroking at her cock, making it rise back up to full size and stiffness, but also the unthinkable idea of fucking her own brother... But, then again, she had already just done that, hadn’t she?

She tried desperately to shake of the dark, lewd thoughts and retain her integrity, but the knowledge that such purity was already down the drain allowed more of it to take hold. Surely another session with him wouldn’t be that bad, and she had already came harder than she’d ever had before due to just his throat; his asshole would be even better, no? Even if her sudden influx of lust was just due to the newness of her dick, she might as well find out what else she could do with it...

“F-fine,” Twilight forced out of her mouth in assent, and looked down at Spike, who was still rubbing his claws up and down her shaft in almost worshipful manner, and didn’t react to her voice. Rolling her eyes and growling slightly in annoyance, she moved her grip around her brother’s shoulders to have her palms rest on them, then pushed him away and made him fall over onto his back, the fat purple butt down below now completely exposed to her, completely with absolutely nothing to cover it nor the small purple package between his legs.

It was an odd feeling to take such dominance over her little brother, the mare thought as she magically grabbed the small Dragon by his legs with her massive cock towering above his puny one, but she mostly let her lust drive her actions, lest she freak out and amscray, leaving herself to suffer in an even worse heat for the rest of the week. Neither side of her wanted to stand on ceremony there, and her hands quickly went down to grab onto his plush rear, tightly squeezing those thick cheeks and forcing a sputtering moan from their owner, but her hands swiftly went down towards the valley between those large hills, and pulled them apart so she could see in full glory the large and sweaty anus that let further into his booty.

Swiftly, Twilight’s hips pulled back and her cock was lowered down towards that dark cavern, its turgid length pointing straight toward the pit at the center, and she didn’t let herself hesitate before pushing her dick forward. She could feel the very moment the flare of her stallionhood pressed against Spike’s anus, and the immense warmth passing between those parts made the unicorn suck in a sharp breath through her teeth, realizing just how strong the imminent pleasure was going to be.

A pair of moans flittered out into the open air as Twilight continued to push forward, her own utterance low and almost growly while Spike’s was high-pitched and squeaky, his mind clearly already lost to pleasure as she saw his small penis looking painfully erect as it wobbled around between his thighs. She slowly felt his anus surround her shaft, repeatedly clenching and unclenching haphazardly as the boy couldn’t keep control of his body, and it only served to pleasure the pillar splitting it apart even further than its incredible heat and tightness already did.

The Unicorn was really starting to figure out just how much better it felt to be in her little brother’s asshole than his throat, as while the latter was much slimier and slicker, she was quickly overwhelmed by the sheer heat that almost singed her dick and the strength that held almost a vice grip on her when it was clenching, forcing her to only move it wasn’t. She lost track of her progress for a short while as she continued plunging deeper in, more and more of her glorious new length experiencing the luscious, moan-worthy dragon butthole that gripped it tight and heated it up.

Eventually though, Twilight could go no further, and she blinked repeatedly as she slowly returned back to awareness, her focus quickly turning to her crotch, where she could feel and see her hips and balls pressed up against Spike’s booty, but a small portion of her cock was still outside his asshole, blocked by the sheer volume of that plush behind. Sighing in a mix of relief and irritation as she got as far as she could for the time being, she then turned her attention to Spike himself, whose back was arched quite a bit while his desperate, cum-filled belly pushing outward and sloshing about somewhat while needy moans burst forth out of his potty mouth, with any words his sister could make out being a plead for him to get his ass pounded by said sister’s cock.

Well, who was she to deny her baby brother something he so clearly desired?

Taking only a moment to pull her hands up off Spike’s butt and wrap around his thighs, Twilight then started to pull her cock back out of him, feeling the hot constricting clenches repeatedly stop her from moving again, but she could tell it was getting a bit weaker, either by her brother’s exhaustion or his rectum getting used to the thing stuffed inside. Of course, that deep asshole did seem to desperately want her cock to be inside, as its retreat left a hollow feeling on Twilight’s shaft, the less warm open air feeling almost chilly against her ass-juice-slickened rod while the amount of it that was surrounded by that delicious Dragon hole truly made her want to return as soon as she could.

And of course, she was hardly able to resist her own body’s desires either.

Twilight, after only getting about two-thirds of her stallionhood outside her brother’s booty, quickly shoved it all back inside in a fraction of the time, forcing another pair of sharp moans out of both siblings as their parts met and slid against each other, even if a small part of the Unicorn’s shaft was still left just outside. Twilight wanted nothing more at that moment than to fix that error, and from how Spike was writhing in lust under her, his cock drooling (relatively) copious amounts of precum, he certainly did as well.

Pulling her cock back out once more, Twilight took more care to pull it out until mostly just its flare was left within the tight confines of Spike’s anus, and then swiftly rammed her hips forward again, making her balls audibly smack against his butt while her cock slid inside and got perhaps just the slightest bit further in there. This time, though, she didn’t hesitate before pulling her stallionhood back out, and then thrusting back in, no time or real care given to how far her cock was getting as she simply knew it wasn’t enough, and she kept thrusting.

Again and again the newly endowed mare shoved her cock into her little brother’s asshole like she’d done it all her life, her hips and nuts flying back and forth to repeatedly smack! against his fat, thick, and plush booty, the former of her parts staring to feel the burn from moving so much so fast and the latter beginning to sting from all the slapping against them. She started to pant as well from the ensuing exhaustion, her previous orgasm doing her no favours either, but her voice was practically inaudible amongst the rising tide of loud, lewd moans coming from Spike’s drooling maw.

Twilight looked down at his face as she kept pounding away at his butt, seeing the normally cute and innocent face of her baby brother having become a depraved slut that only wanted his ass to get further ruined... and some part of her really to get going at that thought. Her pace hasted and her force increased, the repeated smack!s getting louder and faster while Spike’s voice started to break from his constant moaning, his new ‘pudge’ hefting about as he shook from the rutting, his small cock throbbing and wobbling wildly with precum spurting out like a broken faucet until--

He came. Just from getting his ass rammed in, his cock spurted out thick strings of gooey cum that fell and splattered back down onto his belly, penis, and crotch, trailing down them until it reached the point where Twilight’s continued pistoning hips smacked into the cum and smeared it onto her body. That thought, that feeling of her brother cumming to only his ass getting used by her, and that cum starting to run down and stick against her own body... that truly took any doubt away from her mind and utterly resolved her to absolutely wrecking him.

Twilight threw her hips back and forth as fast as she physically could, the bed she was on starting to rock from her motions while her stallionhood became a blur of motion as it rammed in and out of Spike’s anus, any sense of tightness to that hold utterly gone from all its pounding. The little Dragon himself was arched back a painful amount, his mind completely consumed by pleasure that was only furthered by what should’ve been agonizing; his asshole throbbing in what should’ve been agonizing rugburn (or was it cock-burn?), his butt cheeks a searing red from the many harsh smack!s of hips onto them, his belly sloshing back and forth with all the seed already poured inside of him, and his cock simply unable to stop cumming and leave his genitals even a moment of rest.

However, Twilight was much more consumed with the act of thrusting into him, her body a feral beast fueled by lust, unable to care for the pain that should’ve ripped through her cock from how fast she was sliding along Spike’s insides nor how her balls should’ve stung with all the slapping they did onto her brother’s booty. She was panting and drooling at this point, her tongue hanging out of her open maw that tried to suck in as much air as it could to keep her going, what little there was of her conscious mind at that moment fixed solely on throwing her hips back and forth, with her body forced to keep up her hold on Spike’s legs and trying to tell Twilight of her ensuing orgasm, to no avail.

Despite that stubbornness, her body was still getting closer to cumming, with the telltale signs of her cock starting to throb and her balls starting to clench still being ignored by the mare herself. Instead she just kept rutting away at her little brother, utterly uncaring for any of the taboo that once froze her in place, now only wanting to fill him with the full length of her cock and all the seed she could muster, and as luck would have it, she didn’t have much longer to wait.

Sucking in a sharp breath as the sudden feeling of absolute tension in her crotch shot back into her senses, Twilight had no time to properly react to it before it exploded, and she could only fire off a few more wild thrusts before slamming as hard as she could into Spike as she erupted. Her dick throbbed heartily as it got lodged as deep as it could go into the Dragon’s rectum, her balls clenching with power and forcing her spunk out of them and through her shaft, swiftly making it shoot out the end and splatter audibly into Spike’s stomach, starting to fill it up with even more white gooey jizz than before.

The little dragon’s belly, already quite bloated from swallowing his sister’s first load, started to inflate further with all that spunk, there being so much going into him in fact, that some of it made its way back out around the cock lodged into his butthole and spurted out right onto Twilight’s hips that pressed firmly against his ass. The mare herself grunted and growled ferally as she struggled to keep a hold of herself with so much pleasure coursing through her body, the unfamiliar sensation of cumming with a stallion’s genitals completely overwhelming her, the sensations of cum shooting through and out of her cock, of the jizz filling up her brother’s belly around her cock’s flare, and of the semen smearing against her hips as they ground into Spike’s butt cheeks making it impossible to do anything but simply hold on for dear life amidst this tsunami of pleasure.

Eventually though, after what felt like hours, that wave of orgasm subsided and all the cum pumping into Spike’s stomach petered out, leaving it nice and bloated at the size of a several-month-old pregnancy, but far more plush and squishy from the gooey spunk inside. Twilight was soon to get a good feeling of that, with her orgasm leaving her so utterly exhausted that when all the adrenaline left her, she immediately lost her grasp on Spike’s legs and fell forward onto him, landing right on his rotund belly and forcing some more jizz back out his asshole and around her cock, splattering out between his ass cheeks and her crotch.

Twilight’s senses were still dulled from the intensity of what she just went through, taking quite some time to return, with the first thing she could really feel being the exhaustion that plagued her entire body and mind as well as the burning in her lungs from her rigorous ‘exercise’. The second thing she felt, which must’ve taken multiple minutes to feel after the first, was the uncomfortable thing pressing into her tummy, and it took her beleaguered mind far too long to realize it was Spike’s own bloated belly down there. Mustering all the punitive energy she could gather, she get managed to get her arms down onto the bed and press against them to move herself sideways of off her brother, wincing at her sensitive and semen-smeared cock slid out of the boy’s butthole, now having lost its turgidness, before she finally settled down next to him on her side before she wrapped her arms around him and his big belly.

Still heaving out heavy breaths, Twilight forced herself to focus on thinking about all of what had transpired, with the relative calmness of her mind telling her that her heat had indeed been conquered by fucking her brother, but that then let to debating on what exactly to think of fucking her own brother. It was an incredibly taboo choice made only out of a desperate plea to calm her mind, but Spike was very cute and had an incredibly large butt... and that was to say nothing of his oven of an interior, heating up her cock while in either his maw or his ass and making the pleasure she had inside him all the more powerful.

She grunted in pain quietly as she felt a headache forming, all her thoughts inside her already wracked brain not doing her any good, so she instead just let herself turn her eyes down to her brother’s exhausted face, having gone to sleep in his afterglow and snoozing quietly in the silent room. Closing her eyes as she felt that tiredness bring her closer to sleep as well, she simply let herself fall towards it as she rested her head on Spike’s shoulder and resolved herself to deal with everything that happened when she woke up the next day.

Author's Note

Sorry if that whole thing with Spike mistaking the ingredients was a bit weird; I just mostly wanted this story to have a bit more logic than most stories in this vein.
A potion gone wrong giving a female a penis is such a common trope here, but it always just relies on the idea of ‘it’s magic, so don’t worry about it’, which is always dissatisfying to me, so I took the liberty of trying something a bit more concrete here.
It’s certainly a bit inelegant and a tad long, but I did also build up some stuff for later there, so I think it worked out.
Tell me what you think in the comments; it’ll be useful to have some feedback on this to know what I should do in this type of scenario in the future.