Image(s) that inspired this clopfic can be found by searching “artist:scarletcritter, big macintosh” on Derpibooru. (you must have an account to see explicit images though!)
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Midnight at Sweet Apple Acres. Long after the day’s work was done, the Apple Family was fast asleep in preparation for the next day, all except Big Macintosh, who was not only wide awake, but accompanied by a certain forest-dwelling zebra…

“Now you’re sure this will work, Zecora?” Big Macintosh asked after removing his shirt, tossing it aside as he sat down on the side of his bed.

"Of course, my dear. I have taken great care in preparing this mixture." Zecora smirked a bit to the sight of Big Macintosh's rather muscular body, along with the sizable endowment between his legs. "A very lovely body...this will be quite enjoyable." she eagerly licked her lips as she pulled a small covered bowl from her robe, before removing her robe completely, revealing her own bare body to the stallion.

"Well, uh...whenever you're ready, I guess." Big Macintosh gulped softly as he gazed over the zebra's body, from her noticeably wide hips to the pair of E-cups on her chest; his member beginning to stiffen up already.

With that, Zecora removed the lid on the small bowl, revealing a green liquid with quite a vibrant glow to it; illuminating the dark room quite a bit. Bringing her other hand up to it, she dipped two fingers into the glowing green liquid as she approached the side of the bed, before taking them out again and smearing a couple streaks of it across the stallion's cheeks, as well as a thicker streak along his chin.

"Now what exactly was this supposed to do, again?" Big Macintosh winced softly as he felt the soft fingers smearing over his face, watching as the zebra then coated her palms with the green stuff.

"Mm, you will see, my dear. I promise a wonderful time for both of us." Zecora winked in return before pressing both of her hands to the stallion's chest, leaving a green hand-print on both of his pectorals. She then lightly traced a line around his biceps with both of her index fingers, giving him the appearance of having a green ring around both of his arms.

As more and more of the magical green liquid was smeared over Big Macintosh's body, strange sensations began to course through him; his eyes midclosing a bit while he leaned back on his hands, tilting his head back as well. "Ngh, this feels strange..." he softly groaned, despite the tingly sensations feeling more and more pleasurable with each passing moment; his previously semi-hard shaft now grown to a full erection, standing proudly between his legs and throbbing lightly in time with his quickening heartbeat.

"It will, for a few moments...but what comes next, you will greatly enjoy." Zecora licked her lips as she gazed upon the rock-hard stallionhood before her, watching as a bead of precum formed on the tip. With that, she knelt down between Big Macintosh's legs, bringing her hands down lower and painting a few streaks of the glowing liquid across his belly, pulling her fingers back just as she slid her tongue out and slurped it over the flared tip of his erection.

"Mmnh...!" Big Macintosh groaned softly in response to the light pleasure between his legs; his whole body starting to tingle now as the green liquid glowed a bit brighter, starting to pulse dimmer and brighter as it took effect. His hair began to elongate, growing out and curling around his chin and forehead a bit, while down lower, his pectorals began to swell and soften, plumping out into two soft D-cups. "What's...ah...what's going on?" he gasped in a noticeably higher-pitched voice, looking down over his body and watching as his muscular form slimmed down to a much more feminine build; his hands coming up and grasping the two mounds on his chest.

By now, Zecora had already begun to suckle on the stallion's shaft, her lips pursed tightly around it as she slowly bobbed her head up and down. "Mmmn..." she sighed contently, glancing up at Big Macintosh and seeing the changes her mixture had induced, smirking lightly. "A most lovely mare, this stallion has made. Now for the finishing touch." she closed her eyes again and continued to bob her head, starting to drag her tongue along the underside of the throbbing length as well, only further increasing the pleasure.

"Ah...Z-Zecora...!" Big Macintosh moaned in a now very feminine voice, keeping one arm across her chest while her other hand moved down and gently pressed against the top of Zecora's head as it kept bobbing up and down. The addition of that tongue slurping along her shaft only made her gasp in pleasure, leaning her head back again and blushing deeply; feeling her pleasure building up rather quickly as a result of the ever-increasing tingles caused by the green paint all over her body.

"Mmmnh...mmm..." Zecora continued to sigh contently as she suckled on the throbbing member, lapping up every drop of pre that oozed forth; bringing one of her own hands down between her legs and beginning to rub over her slit, feeling quite a bit of tingling, herself, as the magical green paint moved into the final stages of its effects. Gently pinching her clit between two fingers, she groaned blissfully, feeling the pleasurable tingles concentrating on that one spot.

At the same time Zecora felt strong tingling in her clit, Big Macintosh was feeling equally strong tingles in her endowment, only causing her pleased moans to deepen as her pleasure was pushed higher and higher. "Ngh...th-this feels...great!" she gasped, blushing deeply now as she felt her orgasm rapidly approaching, though with all of the pleasure clouding her mind, she didn't notice that her member was rapidly shrinking, receding in towards her crotch.

"Oh yes...I certainly agree!" Zecora thought with a mental giggle, panting softly through her nostrils as she continued to lightly rub and squeeze at her clit, feeling it begin to swell as Big Macintosh's endowment shrunk in her mouth. This only prompted her to purse her lips even tighter around it and bob her head even faster, eager to bring the transformed mare to a strong orgasm before she completely changed.

As her endowment shrunk and shrunk, Big Macintosh's impending orgasm only drew closer and closer; the pressure in her loins building up higher with each passing moment. "Zecora...nnh...ah, I'm...c-cumming!" she cried out, bringing her other arm off of her chest and leaning back onto it now as she pushed her hips against Zecora's mouth and instinctively bucked a bit against it.

"Mmmph!" Zecora grunted lightly from the sudden pushing, but continued to firmly suckle on the couple of inches left of Big Macintosh's member, feeling it slip past her pursed lips as it shrank down completely, taking the shape of a clitoris on the mare's newly-formed pussy. With her mouth finally free, she sighed happily and licked her lips, watching as a few squirts of female sexual juices gushed from Big Macintosh's slit. "Ah...the transformation is complete."

Big Macintosh let out a groan as she collapsed back on the bed, exhausted from the potent orgasm; her chest rapidly rising and falling as she panted heavily. "Ahh...ahh...oh sweet Celestia..." she moaned, taking a few more moments to catch her breath before sitting back up again, shaking her head gently. "Zecora...nh...what did you...do to me?" she groaned, looking down again and noticing that her male endowment had disappeared completely, causing her pupils to shrink a good deal from the sudden shock.

"Mm, I have just...borrowed something from you, Big Macintosh." Zecora gently licked her lips clean of carnal juices as she stood up again, Big Macintosh looking up again and blushing heavily as she saw her own member, now attached to Zecora in place of her clit, lightly bobbing up and down each time it throbbed. "I must say...it is quite a lovely endowment." she smirked as she stroked her new cock with one hand, feeling every throb and twitch it gave. "What a girth, too..you must be a very popular stallion, Big Macintosh."

Still a bit shocked from the revelation, Big Macintosh simply stared in disbelief at the throbbing futa cock in front of her eyes; quickly feeling her own arousal rekindling as the situation really began to sink in. The fact that Zecora had essentially "stolen" her malehood was strangely arousing to her, from both the fact that the lovely zebra was now even lovelier, and a strange sort of submissive feeling from having been emasculated by said lovely zebra.

"Well then...shall we continue, my lovely mare?" Zecora grinned down at Big Macintosh, still slowly stroking her new piece of equipment while her other hand came up and grasped the mare's shoulder, gently pushing her down onto her back again. "I cannot contain my excitement, as you can surely tell." she teased as she leaned down over Big Macintosh's body and moved both of her hands to the mare's chest, lightly squeezing and fondling the two soft mounds.

"Nnh...Zecora..." Big Macintosh moaned cutely from the soft teases to her chest, her nipples perking right up against Zecora's hands as well. "Th-this ain't...permanent, is it...?" she managed to ask before tensing up a bit as Zecora moved her hips forward, pressing her erection against Big Macintosh's moist sex.

"Do not worry about that now, my dear. For now, let us enjoy this wonderful potion." Zecora winked before leaning in further and pressing her lips to Big Macintosh's while simultaneously pushing her hips further forward and penetrating her warm slit; both of them groaning happily into the kiss from the resulting pleasure.

Big Macintosh tightly shut her eyes from the penetration; a bit painful for a brief moment before the flared tip of Zecora's shaft began to rub along her silky inner walls, sending ripples of pleasure through her lower regions. "Mmmnh...!" she groaned and winced softly from the foreign feeling of female pleasure; her arms coming up and gently wrapping around Zecora's back, hugging her gently, which caused their soft chests to mash together quite nicely.

Once Zecora had pushed herself roughly halfway inside, she slowly pulled back from the kiss and sighed blissfully, glancing down at the softly-panting mare and grinning lustily. "Oh my...this potion is working...mm...much better than I had imagined." she spoke between her own soft panting, before leaning back up a bit and continuing to push her hips forward, sinking her throbbing erection deeper inside the mare's heated sex.

"It feels so weird...but so good!" Big Macintosh moaned as she felt the zebra's shaft push even deeper within her; the soft inner walls only squeezing it a bit tighter in response, slicking it up with her carnal juices, which in turn only made it easier for it to push even deeper inside. "Don't stop, Zecora...ngh, I want it all...inside me!"

With a lustful grin, Zecora brought her hands down to Big Macintosh's chest and squeezed her mounds once more, pushing them together and teasingly thumbing over her perky nipples. "Mnh, oh my...you're squeezing me so tightly, my lovely mare." she teased, gently bucking her hips to push even deeper, only a few inches remaining outside of Big Macintosh's sex. With one last thrust, she fully sheathed her member inside, letting out a pleased groan as she squeezed the two red breasts together a bit more firmly. "What a wonderful feeling...!"

The futa zebra only took a few moments to savor the feeling of having her whole length inside the warm love tunnel, before pulling her hips back, sliding back out again until only the flared tip remained inside. "Now comes the real fun, Big Macintosh, my dear." she teased, smirking down at the softly-panting mare as she thrust back in again, watching her squirm a bit and moan cutely in response.

"Ah...!" Big Macintosh leaned her head back a bit, gripping at Zecora's back a little tighter from the shock of pleasure between her legs, feeling the throbbing length being shoved right back inside her; even more potent ripples of pleasure coursing through her as the thick flare rubbed more firmly along her inner walls. "Zecora...nhh, that felt...so go-ah!" she gasped as the zebra quickly pulled back and thrust again, then again, working up to a steady thrusting in only a couple moments.

"Oh yes...it does feel, ahh, quite heavenly!" Zecora moaned, pressing her hands down a little more firmly onto Big Macintosh's soft chest as she kept thrusting away into her hot snatch, enjoying the foreign pleasure just as much as the mare she was stuffing. "Such a tight squeeze...mmnh...from such lovely insides...!" she softly grunted, her own hefty melons jiggling and bouncing a bit above Big Macintosh's face from the force of her movements.

Of course, that tight squeeze gradually became tighter and tighter as Zecora continued to steadily buck her hips, her hands sliding up from Big Macintosh’s soft chest and grasping her shoulders now. At the same time, the zebra’s shaft oozed more warm precum, smearing all along those tightly-squeezing insides, only helping to further increase their warmth.

With each thrust feeling like it was going deeper than the last, Big Macintosh reached back and grasped at the bedsheets, panting a bit more now as her pleasure was pushed higher and higher. “Ooh...d-don’t stop...Zecora!” she groaned, looking up at the zebra with quite a lustful gaze, watching her sizable chest jiggling from each of her thrusts.

“I have no intention to...mnh, my horny little mare!” Zecora teased with a lustful smirk, putting even more power behind each of her thrusts now as her own pleasure grew; feeling a noticeably different pressure building up between her legs as her orgasm rapidly approached. “I want to see how this new equipment...ahh...climaxes!” she grunted softly, leaning forward a bit further and gripping Big Macintosh’s shoulders even tighter to support her rough thrusting.

As the lustful zebra thrust even harder, her member was able to push even deeper within Big Macintosh’s snug insides, easily pushing into her deepest reaches and hitting a very specific point deep inside. Immediately, Big Macintosh gasped and cried out blissfully as the flared tip of Zecora’s shaft roughly bumped her G-spot, arching her back and squeezing at the bedsheets. Her body was still reeling from the pleasure though when the zebra’s shaft pounded against that sweet spot once more, forcing another surge of pleasure through her.

“Seems somepony is, ah, really enjoying herself too!” Zecora groaned between her rough thrusts, feeling the silky inner walls squeezing her length over and over again, returning some of the wonderful pleasure. Just a few moments later though, Big Macintosh cried out once more and squeezed the bedsheets tightly as she was finally pushed over the edge; her insides clamping around Zecora’s member while a flood of her juices gushed forth, soaking over every inch of it.

With that one last squeeze, Zecora closed her eyes and grunted blissfully as her pleasure peaked too; thrusting her hips a couple more times before burying the length inside Big Macintosh and groaning out loudly, beginning to pump the mare’s snatch full of seed. “Ooohh, my…!” her eyes rolled back from the foreign pleasure of male orgasm, while her hips continued to press firmly up against Big Macintosh’s crotch, keeping her length lodged deep inside the squeezing slit as it released gush after gush of seed.

The rush of internal warmth only amplified Big Macintosh’s afterglow; a soft groan escaping her throat as her grip on the sheets slowly loosened and her body straightened out again, laying flat on top of the bed. “Oh...sweet Celestia...ngh…” she softly gasped and panted, still catching her breath from the magnificent orgasm that had just rocked her body, her eyes slowly opening again to glance up at Zecora, who also had quite a pleased look on her face.

“Mm, agreed…” Zecora let out a pleased sigh as her orgasm subsided, feeling quite a bit of her seed oozing out around her member and dripping onto the bed and floor below. “That will be one orgasm...I will not soon forget.” she opened her eyes and grinned playfully down at Big Macintosh for a moment, before leaning down and cuddling against her, kissing her deeply once more as their chests squished together.

“Mmmnh…” Big Macintosh, feeling too weak to do much else, simply closed her eyes again and accepted the zebra’s kiss, savoring the warmth being shared between their closely-cuddled bodies. Once Zecora pulled back, Big Macintosh opened her eyes again, looking down at her female body. “Uhm...s-so...when does this wear off?”

“Do not fret, my dear Big Macintosh. The potion’s effects are easily counteracted.” Zecora smiled and stroked a hand over Big Macintosh’s cheek, before pulling her hips back and sliding her softening member out of the warm snatch that was still gently squeezing around it. “You will be back to your former self in just a moment.” she added, bending over and reaching into her robe, which was in a heap on the floor.

When she stood back up again, she was holding a flask of cyan-colored liquid by the neck, gently swishing it around for a moment, which caused the liquid to quickly change to a darker shade of blue. “With this antidote, our bodies shall be restored.” she then tipped the flask towards Big Macintosh’s body, splashing the dark blue liquid all over her; the green painted lines all over her body immediately washing off as the liquid came into contact with them.

As the last of the blue liquid washed over Big Macintosh’s body, it began to rapidly gain muscle and bulk up, returning to its normal male size and proportions; his soft breasts shrinking down and flattening out into beefy pectorals, while the slit between his legs disappeared, quickly being replaced by his usual male endowments, which had disappeared from between Zecora’s legs. He rubbed his head gently as he sat back up again, glancing down over his body and sighing contently, glad to have his male form back. “Wow...that sure is some freaky potion you’ve got there, Zecora.”

“Hehe, it is quite a basic concoction, Big Macintosh. But quite impressive, yes.” Zecora giggled and nodded as she slid her robe back over her body, returning the now empty flask to the inner pocket of the robe, along with the covered jar of green liquid. “This has been quite a pleasant experiment, my dear. Perhaps we shall do something similar in the future.” she added with a wink, before leaning in and gently kissing the end of Big Macintosh’s snout.

“Heh...sounds good to me.” Big Macintosh grinned and nodded in return, before leaning back onto his hands, sighing contently as he watched the zebra slip out through the window that she entered through and headed back towards the Everfree.

LE END