Mark wanted to sit and watch her expand, wanted to see his fetish carried out in the flesh. But he knew full well Luna wouldn’t like him simply watching, especially with how aroused she already was. So he wasted no time in moving up and pushing the throbbing bulge in his shorts against her bloated bum. His hands caressed her fat flanks, the expansion reaching them and starting to push them out.

“Hmm, you enjoy your princess fat with gas?” she teased, grinding her marehood against that bulge, a hoof pawing at the ground as her arousal grew with her body. She already resembled an overly pregnant mare who perhaps spent a bit too much time at the buffet, but she could also feel her teats expanding, the gas filling her chest and starting to fatten up her limbs. She could also feel her body growing lighter.

“Oh...love you no matter how you look, Luna! But...oh gods, to actually enjoy this,” he said, hands quickly going to his belt and undoing it, repeating the process with his fly and shedding his shorts and boxers. He didn’t waste time with his shirt, grinding his bare cock against the warm, moist flesh of her marehood. He could feel a climax building already and quickly pulled away, getting a whimper from his marefriend. However, upon feeling his hands pulling her marehood lips apart, she giggled in anticipation, knowing what he was up to.

While many of her male lovers had felt it proper that she orally pleasure them first, Mark was a surprising and pleasant change. Whenever he and his three lovers had had their fun, he’d always insisted on pleasing them first. Not always the same way, of course, but always first. And considering how amazing his hands felt compared to hooves and magic, they were rarely inclined to argue. And since Luna’s magic meant he could orgasm far more than normal, he was clearly doing it out of simple chivalry.

“Mmm, my apologies...ohhh...in advance...if I...oh gods...make a mess! This is...yessssssss…most delightful,” she cried as he attacked her marehood, licking up and down and in circles on her slit, then pushing his lips against her so his tongue could lash along her inner walls. He groped and squeezed her rear as the cheeks ballooned against his hands, her tunnel likewise swelling up around his tongue. He couldn’t see to be sure, but she was surely losing any semblance of a mare and taking on a ball shape. He could feel her body starting to lift off the ground, though slowly.

For a moment, a part of him wondered if Luna would enjoy something else from his dream...but he dismissed it for now. No sense in that when she was doing such a good job inflating herself.

He found her swollen (and still swelling) clit and gave it a gentle nip, drawing a squeal and a gush of her mare juices. She was getting close, and while he sometimes teased her and drew out her climax, he doubted she was feeling patient enough for it now.

And so he gave her clit an almighty bite, his reward being a loud neigh that echoed off the walls of the room. This was followed by a rather powerful squirt of her mare juices, Mark quickly pulling back before the squirting became too much. He let her coat his face and body, ignoring the feel of his shirt sticking to his chest.

He couldn’t be one hundred percent sure...but he could swear her climax was much more powerful. Was this because of the pressure in her? Or has she just been holding in more than her gas?

“Oh...oh sweet maker...that was...oh...words fail me,” came her voice from ahead, Luna sounding quite out of breath...but very content. He moved around her now massive body, noting that the hissing sound had stopped. He paused and took a good look at her.

Mark had seen Twilight’s hot air balloon a few times, and he tried to form it in his head and turn it to the side for a proper comparison.

Luna had to be almost as big around, though she wasn’t quite as long. Her limbs weren’t quite swollen into cones, but bulges had formed where they met her body. Speaking of body, it seemed most of the gas had filled her belly. Her back had rounded out a bit, but she wasn’t quite a total sphere. And her wings were completely untouched...though they were out in a nice wing-boner.

He moved around in front of her and looked up, seeing her face had been pulled back into her puffy body, her neck a fat inner tube. He hesitated for a moment, then began to roll her down, bringing her face to his.

She was blushing a lot more heavily now and her eyes seemed a bit...sparkly. But she met his with no trouble, a smile gracing her muzzle. He returned the smile and caressed her cheek, chuckling as he saw her ears had puffed up a bit. Not as much as he’d expected, but certainly enough to be obvious. Seeing his gaze at them, she shook her head as best she could.

“Neigh, not just yet, Mark. I wish to recover from that...glorious climax you just blessed me with. Besides, is it not your turn?” she asked, giggling when she saw his still throbbing cock, a bit of pre leaking from the tip. “Hmm, if I could find a way to show it off without being known, perhaps I could introduce a new standard of ‘sexy’,” she said.

“Heh, yeah, not that I’m ashamed or anything, but I don’t think this part of our relationship needs to be public,” he said, following her gaze. “Heh, you know, when I was eating you out, I briefly wondered if a literal blow-job was possible with you,” he said, feeling his own cheeks heat up more, his tongue licking his dry lips.

“Oh? Perhaps you’d like me to try it now? As much as I love your physique, I wouldn’t mind seeing how you look puffy,” she said with a very devious grin, slowly but audibly drawing air in through her nose. He felt his heart skip a beat...and his cock jump and spurt.

“Heh, as curious as I am, I don’t think it would be a good idea right now. We know you can inflate safely, but are you sure I can?” he asked, seeing her look of mischief soften into a concerned frown for a moment. She nodded, the smile returning as she moved to nuzzle his cock.

“Hmm, perhaps tis best. However, I doth believe I have a favor to return...and the sooner I finish, the sooner you can take your blimp properly!” she declared, tongue starting to lap at the head of his cock, happily licking up the pre that had coated it. He groaned and grunted, hands moving to caress her neck and cheeks. He may not have been insistent on getting a blow job, but he certainly didn’t mind them.

“Ohhh...have...uhhh...have you talked...Rarity and AJ about this?” he asked, thrusting a bit as she took the head of his cock into her mouth and suckled on it a bit, then pulled away with a loud pop.

“I did. I believe they’re currently...experimenting. Seems lady Applejack has already experienced it outside of the sexual play and they both wished to learn a bit more before they...indulged you. But rest assured, they were quite amicable to the idea,” she said, nickering and moaning as his hands found her ears. Being puffy, they were much more sensitive and it was all she could do not to become a purring kitten.

Focusing herself, she opened her maw and took his cock in, bobbing her head up and down as much as her swollen neck would allow. Mark showed his appreciation by starting to thrust, though keeping it gentle. His fingers teased all over her ears, Luna’s right hind hoof twitching and her tail wagging happily. She bobbed her head faster, easily suppressing her gag reflex to take more of him in with each dip.

“Ohh...getting...getting close,” he groaned, not having to ask how she wanted it. When she wanted him to cum on her face, she worked his cock like a popsicle; when she deep-throated him or kept it in her mouth, she wanted to swallow it down. And she made no move to free his cock, so she clearly wanted her delicious snack.

Luna slowed her bobbing and brought her head back until his cock head was in her mouth...and he came with a loud groan, thrusting as spurt after spurt of his seed filled her mouth. He knew he wasn’t as productive as a stallion (at least not without a little magical help), but Luna murred around his cock as she let him fill her mouth. He pulled away from her, her lips sealing shut as she audibly gulped, looking up at him with half-lidded eyes and a coy smile.

“Hmm, still delicious as always, beloved. Though I think I may start working some magic on you to make you more...productive. This expansion has me a bit curious about another type I’ve heard about,” she said, making a show of licking her chops like a feline after a nice meal. Speaking of magic, her horn glowed and a similar glow appeared around Mark’s cock, the human groaning as he slowly came to full staff again.

The first time Mark had needed a bit of magic to keep going after his first climax, he’d been so terribly apologetic that it had actually tugged at Luna’s heart. It was yet another reminder of his being the sole one of his kind here and thus knowing he was being compared to an Equestrian. However, his lovers had assured him that they’d know full well what they were getting when they decided they were all in love with him. And they wouldn’t trade what made him unique for the largest, most sexually-skilled stallion in Equestria.

“Hmm, are you ready to take me, dear Mark? I’m most eager to feel the difference being so full and tight will make,” she said, blushing as she accepted just how helpless she was right now, even with full use of her magic. In their past lovemaking sessions, it had been easy to make sure he kept her status in mind and remind him just who was the dominant lover. It would be different this time, her bloated form meaning she would be unable to tease him or control the process. And Alicorn magic like hers would require she be able to see what she was doing.

Mark offered her a warm smile, those hands of his once again scratching an ear. “You know I’d never do anything you didn’t like. And I’m not about to abuse the trust you’ve given me by doing this,” he said gently, playfully booping her nose. “Still...I hope you don’t mind if I...indulge myself a bit. You know how much I love your ass,” he said with a chuckle, rubbing a hand along her bloated barrel as he made his way behind her. Her body was floating about a foot off the ground, her magic keeping her from floating too high, but he still had to roll her back again to get at his target.

“Heh, you cum again, Luna? You’re drenched back here,” he said, certain she hadn’t been this messy when he’d made her cum. Her marehood was winking again and her tail was practically a blue blur. He got in the proper position...and gave her bloated butt a good spank, the sound echoing through her inflated cheeks and drawing a squeal from the mare.

“Ohhh, Marrrrkkkk! You promised not to tease meeee!” she whined, her ass cheeks much more sensitive like the rest of her, the delicious sting of that spank echoing through her privates and seeming to jolt her clit and labia. A gush of her juices came from her and she let out a needy whine, trying to push herself back with her wings.

He had indeed, and so he lined himself up with her sopping, hungry tunnel and began to push in. He grunted a bit as he felt the warm walls of her tunnel squeezing him, though it was more pleasant than anything. He’d always been a bit on the small side for her (not that she ever complained, as he could still work her privates in the most delightful ways), but now he actually felt just the right size. He began to thrust, grunting and groping her ass cheeks as he worked into a rythym.

“Oh yesss! Harder, please! You know...ohhh...I like it rough!” she cried, her wings starting to fidget in delight, her hooves flapping as much as they were able. He could work some magic on her when he took her normally...but now? Now she was so much tighter, her tunnel so much more sensitive that she could already feel the giant spring of her climax starting to coil inside of her. She grit her teeth and shook her head, willing it to slow. Mark still had a ways to go to reach his and she would not let herself be wore out before he came.

Mark obliged her and began to increase the pace of his thrusts, her tunnel walls undulating around him with the beating of her heart. He groped and squeezed her butt cheeks, making sure to rub over her cutie mark. He noted her puckered bumhole and moved a hand in between her butt cleavage, fingers stroking back and forth over her rear entrance.

“Oh...you naughty boy! Always teasing my other hole!” she cried, though they both knew she loved getting the dual stimulation. Heck, he’d done her in both holes more than once by using a toy. She neighed and groaned and squealed as his hips began to smack against hers, giggling at the hollow pangs the contact made. Perhaps it would be worth exploring what other kind of fun being a balloon could entail aside from the sexual type.

“Ohhh Lunaaaa...you...you want to cum first?” he grunted in between thrusts, her clenching tunnel making him unable to even think of holding his climax, pre already spurt into her. He gave her ass another smack to try and pull his mind from it, but it was as if her body were trying to suck his climax right out of him.

“Ohhh...don’t...don’t hold back! Let’s...let’s just… let it happen!” she cried, knowing she couldn’t hold back either, the pleasure sending lighting through her body and fogging her head. And sure enough, her climax came first, her walls clenching around his cock and her whole body seeming to clench as she came. She squealed and arched her back, wings stiff as planks, her hooves pushing out, a loud neigh escaping her gaping mouth.

Mark wasn’t far behind, her walls clenching hard and finally drawing his climax out, the human groaning and slamming himself flush with her so not a drop of seed was wasted. As far as he and everypony knew, he couldn’t knock up an Equestrian...but that didn’t mean Luna didn’t enjoy the feel of his seed filling her womb.

He felt his legs trying to buckle under him as his climax died off, his body drenched in sweat and his muscles feeling as if he’d just done a heavy workout. Luna was likewise slick with sweat, their juices leaking a bit from her marehood. Mark grunted and let himself all against her, breathing fast and hard as he waited for his body to recover.

“Luna...you...you still with me?” he asked, noting her tail was now slowly swaying back and forth in contentment, occasionally lifting to brush against him. A snort and a groan was his answer...followed by a light giggle.

“Hehe...sorry, dear Markie...but it seems I’ll only become a blissed out silly filly in your dreams,” she replied, her voice a soft purr. That got a chuckle from him, the human pulling himself free and staggering around to her front.

Luna’s face was the picture of relaxed contentment; cheeks slightly flushed, eyes semi-glazed, smile relaxed and full of warmth and pleasure. He didn’t know if her current state had a hand in it or if she was as she always was after their lovemaking, but it was a pleasant sight nonetheless.

“Hmm, always so content and beautiful after a good rut,” he said, moving over and sitting down a bit beside her, resting against her body. With a bit of effort, she moved her head enough to nuzzle his head, Mark lifting his so he could kiss her on the lips. It wasn’t a chaste kiss, but it wasn’t a hot one. Just two lovers enjoying being close.

“I must say, Mark, that that was quite the experience. Perhaps there are other hidden delights in your dreams that I have been missing out on,” she said, idly wondering why it’d never occurred to her to try this fetish before. She also couldn’t help but wonder how her sister would take swelling up into a big balloon. “Hmm, might you be up for resting upon my back, beloved? I’m not quite ready to deflate and I’m sure you would like to rest and recuperate,” she said, certain that she was wide enough back there to be an impromptu bed for him.

“Oh, you know I’m always up for our after-sex cuddles,” he teased, chuckling as she lifted him in her magic and deposited him onto her back. He got comfortable between her wings and moved up a bit so he could rest his head upon the fat tube of her neck. She nickered her appreciation and brought her wings down over him.

“You said Rarity and Applejack were looking into this. I take it they’re interested in the fetish as well?” he asked, idly caressing her neck.

“Oh, Applejack was certainly open to it. Rarity...well, she might require some convincing. I dare say that’s part of what’s being done right now,” she said, rather curious herself as to how the other two mares felt about it.

"And...how do you feel about Zecora?" he asked, suddenly remembering the rather interesting journey he'd had coming out to the castle. While he wasn't sure how serious Zecora's flirtations had been, he didn't want to leave her feeling led on.

"Hmm, well, I do trust her enough to guide my beloved through the Everfree. Why?" asked Luna, trying to turn and look at him, an eyebrow raised. She wasn't too familiar with the zebra on a personal level, having only really met her during her first Nightmare Night celebration in Ponyville. She seemed harmless enough, if certainly not sharing many pony customs.

"Heh, well, she was rather...flirty while bringing me out here. Nothing too extreme, but even I could tell she wasn't just teasing me. I think she wants a roll in the hay, as Applejack would call it. I know I have to talk with her and Rarity about it too, but...well...would you be open to me indulging her?"

Elsewhere

“To his herd, Markie is unquestionably loyal. And that, I know well, I should never wish to foil.”

Zecora had certainly enjoyed her time with the famous "Equestria's Only Human", even if he'd clearly been bashful in reply to her flirtations. Despite what she knew many thought (and which she didn't really care about), she didn't consider herself a slut when it came to sex. She just wasn't interested in only being with one lover...at least not yet. And so long as the other party was willing, she saw no reason to deny their interest in her.

Still, she knew about Mark's herd and could appreciate his unwillingness to be unfaithful at the moment. That didn't make her interest in him disappear...especially after she'd gotten such a show after deciding to be a voyeur. Her marehood was still drooling from the climax she'd given herself from the show.

"But he's also unusual, so full of potion potential. And that he is kind yet so kinky makes his presence essential."

It certainly wouldn't hurt to ask. And she doubted his herdmates would treat a simple request with much hostility so long as she was respectful about their relationship. And, looking over some of her many potions, she could think of a few ways to make her request more appealing.

"I could ask of his herd that they might allow me his use. And perhaps him, by inflation, I might successfully seduce?"

Author's Note

There will be one more chapter showing what AJ and Rarity have been up to.

Do be gentle with the criticism, as I'm sure there'll be plenty. As I've said, this is the first lewd work I've done outside of an RP and I know it's not award-winning material.

And mucho appreciation to Firesight - Fimfiction for helping me write out the lines from our favorite zebra. I couldn't do it to save my life.