The machine Ro-Barb had first emerged from, which had undergone a few changes in more recent times, served as the main source of light in the laboratory, casting its magical glow over the scene. Most of the stuff that had previously been there had been removed, mostly to make space for all the extra occupants that resided there and for the considerable size of a few of them.

Spike sat to a side, the only male creature in the room and by far the biggest, his back against a wall and his heads almost reaching the ceiling. There were three of them, just as there were three monstrously sized shafts protruding from his crotch, each being attended to in different ways by his multiple lovers.

Starting from the right was his most recent addition. Gleaming Shield, formerly Shining Armor, looked just about the same as Twilight had after becoming his bitch. Huge tits, a round ass, plumped up lips, and a dumb expression on her face as she speared herself onto Spike's shaft. Her belly bulged to the point it touched the ground, while her arms and legs hung limp as the cock inside her kept her up by itself.

Gleaming's mother looked at her with love, down from her position between two of Spike's dicks, slavishly worshipping all six of his beach-ball sized testicles. Her own tits were not too different in size, and in many other things she resembled her daughter. Her belly bulged however not with cum, but with puppies born from her love to her Master. She would in the not too far future give birth to more bitches for him, and more alphas to continue his legacy. She lovingly stroked her round belly with one hand, her tail wagged happily from side to side and her ears stood up on her head.

Sunset was on her back underneath Spike's middle cock. She was a mirror of Twilight Velvet in how far along her transformation was, and in how full of new life her belly was. The dick above her was long enough to cover her whole as she held her legs up like a dog on its back, and occasionally she would raise her head to lap at the knot hanging over her eyes. That aside, she looked completely out of everything, fully absorbed with dreamlike totality in the act of staring at her Master's dick and inhaling his scent, there on the floor beneath him.

To the two sides of that same middle cock, two more of his bitches sat kneeling, pregnant and kissing his shaft. They too hand undergone quite the transformation, though the other way around compared to most other girls in the room.

On the right was Winona, who Applejack had allowed Sunset to borrow without much question and who would soon be used to lure the farmgirl there to add her to Spike's harem. The bitch had been the second dog to ever gain human-like sapience, and there was something funny in how short the time she'd had to fully appreciate it was. Mere seconds between the moment she rose above her instincts and the moment those instincts took her over again as she was fucked and properly broken by Spike's dick. She was even more worshipful and obedient to him in that state than she'd ever been as a dog, and Spike quite liked the knowledge of that. Though her two rows of tits weren't as big as some of his other sluts', and her canine facial features left her lips a touch less plump than his human slaves', there was still something deeply exciting about her anthropomorphised body, the combination between her dog fur and the hypersexualised humanoid frame it covered, the way her hands and long nails still resembled paws and claws, being both incredibly dextrous and incredibly soft and smooth on his shaft.

Ember was on the left, a mirror of Winona's body, though slightly taller and with bigger breasts. Breaking her and turning her his had given Spike particular pleasure, given how defiant and aggressive she had been. Her spiked black collar was all that remained of her old attitude, the once proud and untamed stray pack leader had been turned into a cock-hungry slut who'd obey any command he'd give her without a second thought, and probably without a first thought either. There was really something extra enjoyable in seeing her so dumb and weak, remembering the way she'd used to bark at him before he'd shown her her place. To think of all the dogs in her pack who'd have wished to bed or more realistically be bedded by her, and he got to breed and break her. And he'd do the same with some of the other bitches there, soon enough, alongside Su-Z's dog once PostCrush's tour was over. Though thinking about it, maybe he'd breed the two popstars as well, not just their pet.

On his left cock, around it and properly stretched by it, the second most recent addition to his harem, and perhaps the most peculiar. After Twilight had gone through all the trouble of fitting her for him, it was a shame that Ro-Barb had to go unused, yet at the same time he was far too much for the body she'd had back then. Thankfully, the same magic that had made him and his pets that much physically better had also proven to be quite compatible with the bot's technology, and so his first ever partner had received an upgrade to match his new self and interests.

And what an upgrade it had been. The robot bitch, perhaps the one most fittingly described as a sex doll out of all his bitches, looked like and literally was built for sex, and damn good sex at that. Her body was an exaggerated caricature of human femininity, with a few hints still there of her canine nature, such as her tail and ears. She only had two breasts, huge breasts, made of soft and pliable rubber and fitted with pleasure sensors to send her artificial brain into overdrive whenever they were played with. Her muzzle looked slightly more dog-like than human, but her mouth looked like neither, and really it didn't look like a mouth at all. It was a hole designed to milk his cock, the thick ring of rubber around it her would be lips, the entire thing and her entire mouth and throat just a hyper-advanced vibrating sextoy. Her hands and hind paws were fitted with vibrating pads, perfect for massaging his shaft and balls. Her thighs were thick and wide, and her ass a mirror of her tits.

She had a single hole between her legs. Technically, it could be counted as her pussy, but the bot was more sextoy than living thing in that regard. The simple truth was that it was a fuckhole, the place Spike was meant to slide his dick in. The core of her being, really. Ass and tits were enjoyable, and the things fitted on her limbs and head were neat, but when one really got down to it Ro-Barb was a hole for his dick with some fancy tech around it to make said dick cum faster and harder. That said high tech masturbator also came with general intelligence comparable to a human's and far greater processing power than any animal brain only made the knowledge of her single purpose condition that much hotter, especially when all her computing power was directed only at making herself a better sextoy for her owner, when the orgasms he gave her didn't make her crash at least. Spike quite loved the way she'd fitted speakers to the side of her head, as to not compromise the sex hole functionality of her mouth, with the added advantage that she could freely worship him verbally even when taking him in her throat. The added vibrations were quite nice on top of that.

But what he loved more than that was fucking her like the hole she was, literally jerking himself off with one of his huge paws around her body like he was doing right then. The sides and back of her torso were full of pistons and vibrators and motors, pressing and massaging his cock, but the front up to her tits was semi-clear and stretchy rubber, and stretch her he did. Her belly looked like a condom as his cock pushed out of it, completely wrapped around it. Soon he knew it would stretch even further, once he came in her and bloated her like a balloon, a sight he always enjoyed. Judging by the static crackling through her speakers at that moment, he'd crashed her main again, probably the new pleasure sensors she'd installed in her insides. She was adamant on cramming as much sensitivity as she could into herself, and while it didn't make her a better toy he certainly didn't mind the way it consistently led to her system overloading whenever he fucked her, often turning her into a limp fuckdoll for him to use until she next rebooted herself. He suspected she didn't mind it either.

And higher than all of them, the first of his bitches, both in terms of order of acquisition and in terms of rank. Twilight was at that moment lying atop his muscled chest, her mouth locked in a sloppy kiss with his central head, far larger and smarter than hers, and she was a sight to behold.

Her belly was round and full, heavily pregnant, easily the biggest thing about the girl, and it would have been pressing against Spike's broad chest had it not been for her second largest feature. Her tits, all six of them in three vertically stacked rows from her original chest down to her belly, had grown even bigger than they'd previously been. They looked close to exercise balls in size, and the combination of her advanced pregnancy and the weight on them meant they were constantly leaking down a rivulet of milk, drenching Spike's fur and spilling over his shafts and balls. Her ass was no less sizeable, huge and jiggly and soft as Spike's digits sunk into its flesh as he held her there, one of his claws slipping in and out of her leaking pussy.

Her long, fluffy purple tail was fully up, wiggling from side to side excitedly. Her thick thighs tapered into long, slender legs than ended in canine hind paws, fur progressively covering more of her limb the farther down one looked until her once feet were practically indistinguishable from a dog's if one looked only there. A little fur had grown in symmetrical patches over her shoulders and back and arms too, and although her hands were still fairly human-like her long nails did slightly resemble a dog's. Her ears had moved to the top of her head, big and mobile, at that moment focused forward. Her mouth and face had turned partly to a snout, still capped by her signature overinflated cock sucking lips, and above them was a dog's nose. Her tongue was longer, and at that moment entangled in Spike's far longer one as he basically fucked her mouth and throat with it.

The bimbo bitch felt really happy. She always did, ever since she'd started wearing her collar and embraced her role, but she was still constantly blown away by just how amazing her life was. Maybe it was just her inability to keep it in mind for too long, too overwhelmed by the pleasure in her present to proper crystallise the past in her memory. Her only occasional source of confusion was whether she should be calling Spike her Master or her Masters, now that he had three heads, but usually she forgot all about that the moment he touched any part of her with any part of his. Her whole body was an erogenous zone at that point, perks of being a fucktoy.

As Spike's central head still swabbed her throat with his tongue, and while one of the others was busy panting and drooling over Ro-Barb as he jerked himself off with her unconscious body faster and harder, the third turned to look to Twilight as well. It extended forward, giving her a few licks that coated her in his saliva and nibbling at her closest tit until it bit her nipple, causing a jet of milk to shoot out and into the dog's maws. Twilight moaned around his tongue, and Spike's other head growled, pleased. Then the central one slowly drew his tongue back, while the other kept licking milk off himself and Twilight's tits.

He could have told her what to do, but that was no longer necessary. A simple nod and the way he looked at her were all that was needed for Twilight to understand and follow his command at that point. Instead he used his mouth for something more entertaining. "You dumb fuckslut," he called her, removing his hand from her nethers as she slowly slid down his pecks, as per his instructions. "You sextoy bitch. Good for nothing but taking dick and birthing more bitches and pups, and when they grow up I'll be fucking your daughters while you fuck my sons." It was redundant at that point, things they'd said again and again and knew well, yet the dirty talk never got old. It never stopped making him hard or making his girls wet. Somewhere below, Twilight Velvet's efforts on his balls grew stronger, indicating how well she received that particular sentence.

"Yes, Master," said Twilight. "That's all I'm good for, so please let me service your beautiful cock." Her voice was sugary, throaty and full of lust. She kept sliding down until she reached his crotch, and then horizontally until she was lying on top of his middle cock, pushing the two dogs there aside. She planted her lips on the top of Spike's knot and kissed and licked it, while her six massive tits slid to either side of his shaft. Winona and Ember wasted no time getting to the ground and suckling on the closest nipple they could reach. They were all sisters there in being Spike's bitches, but among them Twilight was like a mother to them, being the first and Spike's favourite and the progenitor of their condition, and the one furthest along in her transformation to the perfect partner for their Master.

As one head kept panting as its closest hand jerked a cock off with Ro-Barb, the arm on the opposite side reached out the grab Sunset from beneath Spike's dick and Twilight's tits. The girl, still in a dazed state, was placed faced down and ass up on Spike's chest, and his free side head began to tongue her nethers, reaching deep enough into her to make her scream.

His paw then free again, he moved it over Twilight's back, and began to slide her back and forth over his cock. It wasn't hard, with all the milk and drool and pre covering both her body and his shaft. The girl for her part did her best to use her arms and legs to keep her tits pressed around the sides of the dick she was on, giving him an oversized boobjob and spraying extra milk on the floor in the process. She also planted her inflated lips, and really her whole face, over the surface of his dick, drooling out as much as she could as she was dragged back and forth.

It wasn't long between the combined stimulation of her heavy round belly over his shaft and her huge tits on either side of it brought Spike close to the edge of another orgasm, the warmth and tightness of her whole body simply delicious around him. But he had no intention of simply spilling his load all over the floor, even if doing so and then letting his girls lap it all up was a pretty enticing idea. But not right then. He stopped jerking himself off with Twilight's boobs and body as a toy, and instead used his claws to raise her head so she was looking at him by grabbing a pawful of her mane. "On the ground, slut," his middle head said. The others were still busy respectively panting over Ro-Barb and ravaging Sunset's pussy.

With a smile as dumb as it was happy, her tail wagging side to side excitedly, Twilight gave a nod and a bark of acknowledgement, then began to slide off his cock. She made sure to do so by moving towards his tip, and giving it a sloppy kiss as she fully got off, getting a mouthful of thick pre in the process. Once she was on the ground, on her knees, she gave a long worshipful lick to the underside of the oversized shaft, then turned around. As she moved back, Winona and Ember returned to licking the cock she had left.

Spike's free front paw went to the bloated girl on his side dick. He took hold of her and began to slide her off his cock, and his head pushed Sunset down towards the emptying spot. The redheaded bitch crawled down his torso and up his shaft, swallowing all the traces of cum Gleaming had leaked out, and finally she let herself onto the ground, face down buried in Twilight's sister's cunt and eating more cum out of it, ass up and pussy leaking and waiting for Spike to penetrate her.

Still jerking one of his cocks off with his robot fucktoy, Spike slowly began to raise himself up from his sitting position, leaning forward and resting his free paw on the floor and stretching his hind legs as his hindquarters rose. He looked like an impossibly big wolf like that, aside from the one paw still holding the world's most high tech sex doll and sliding it up and down one of his dicks with a frenzied pace. His other two shafts rested on Twilight and Sunset's backs, cradled by the shapely, exaggerated curves of their asses. With no longer enough space to stand there, Winona and Ember had moved to licking and caressing and rubbing themselves against his massive balls, and Twilight Velvet had dragged her older and still barely conscious daughter there to do the same.

Spike drew his hips back, his tails raised, lining himself up. His side shaft poked against the wet entrance to Sunset's leaking pussy. His middle one aimed a little higher, and not just because Twilight's bloated belly and milky breasts kept her so raised above the ground. The tip of his cock found her anus, and entered it with ease. Her entire body was a thing born for sex after all, her every hole was always ready for him and easily able to stretch itself to accommodate his length and girth. Two of Spike's heads grinned, the third still busy drooling like a dumb dog. Then his hips thrust forward.

He slid into both girls with ease, stretching them wide with his shafts, and he didn't waste a second after that. He began to thrust back and forth, faster and harder, leaning down and pressing their bodies to the ground with his muscled furry bulk while ravaging them doggy style. The sound of his hips slamming against their sex doll asses echoed loud around the room, mixing with that of their own moans. It wasn't long before Twilight's cries of pleasure turned from incoherent words to incoherent barking, her mind overtaken by her more primal instincts. All the while, his remaining bitches all worshipped his many balls, their inflated lips constantly pressed against them as they drooled all over their surfaces.

Spike's thrusts against Sunset and Twilight were so forceful that the only thing keeping them from sliding forward with each one was his body pinning them to the ground. His hips moved like a blur, all three of his heads panting with their tongues lolling out and drooling onto the ground, his brains single-mindedly focused on his need for pleasure, his need to fuck and cum. He growled and grunted as he maintained his brutal rhythm, enjoying every moment of the girls' bodies wrapping tightly around his shafts, every second of his cocks sliding on and out of them sending electric thrills all through the surface of his shafts that turned his mind to a fuzzy, tingly field of thoughtless, lustful instincts.

With the girls cumming around him in seconds, spilling their juices all over his dicks, it wasn't long before he was about to orgasm as well. It wasn't supposed to be long, that was the point. With his bitches made into fuckdolls that good it was only natural for him to cum so fast when really taking advantage of their bodies, and he wouldn't have had it any other way. The sooner he came the sooner he could get to cum again after that, after all, and bloating his girls up was always something he relished the sight and feeling of.

A warm tension spread over Spike's body. His pants became guttural, his thrusts slowed before picking speed back up again. With one strong push of his hips, he pinned the two girls he wasn't holding into the ground, and his knots forced their way into their holes. The same happened with his robotic partner after a few more moments of jerking himself with her. His six balls tensed as the members of his harem he wasn't fucking slobbered over them and worshipped them with their bodies. He threw his three heads back and howled and his free hand clawed holes into the pavement.

Spike came inside all three of his partners. His body quivered as he shot rope after rope of thick warm cum into their bodies, as they came and screamed in unison with him. Their bellies bloated, their eyes rolled back, their mouths open. Ro-Barb's elastic belly grew too wide for Spike to hold her and he dropped her to the ground, cushioned by the size of her inflated insides, still growing larger as Spike kept cumming. He rested his now free paw onto her back, not crushing her sturdy mechanical body but still causing some of the cum to seep into the rest of her robotic insides and leak out of her elsewhere.

After a few minutes of spurting into the girls, all the cum firmly kept inside them by his knots as they came over and over and shook around his shafts, Spike finally calmed down. His howling died down to slow pants, his tongues drew back into his mouths. As the three girls lay half unconscious on the ground with enough cum inside them it weighed more than they had used to, before getting their assets expanded and their bodies filled with new life at least, he slowly stretched his back and then began to draw back from them.

His cocks came out of their insides with loud plops, and immediately the sluts who'd been tending to his balls were hungrily on them, or eating the cum leaking out of the ones he'd just filled. Spike sat back against the wall as his bitches busied themselves servicing him. Winona and Ember, overtaken by their primal urges at the sight of him breeding the others, wasted no time in spearing their pussies on his cum-covered cocks, eagerly sliding up and down them while Spike lazily watched them. Twilight Velvet, the wisest of his slaves as much as any of them could be wise, took the remaining cock for herself and began to glide her massive milky tits up and down it, kissing it and licking it along the way.

Gleaming, left without a shaft to please, lazily crawled to her sister's ass and started to eat cum out of it, one hand stuck inside her leaking pussy as her tail wiggled back and forth. Spike watched her with some amusement, but mostly being content after his most recent orgasm.

Ro-Barb would need repairs again, and that meant letting Twilight be for a while so she could actually think of something that wasn't being fucked and have a thought process that didn't amount to barks and pants. That was fine, she'd been a good girl that day. She could be left to herself a little while Spike took care of his other pets. On that matter, Applejack would be coming to see Winona soon, and Rarity would most likely be with her.

Spike gave a lazy upwards thrust with his hips. It was already almost time to expand his harem again. His shafts twitched, his balls tensed, and his three heads grinned. He just couldn't wait to see it through.

Author's Note

I totally didn't base three headed Spike's attitudes on the memes surrounding Legendary Ghidorah. Especially the third head. Nuh-uh.