Test Subject Cynthia

Inflation Types:
Sexual Content:
Date Written: 

Cynthia stepped outside of the Sandy Resort hotel on Io. What have I gotten myself into?

Her best friend, Clarissa Finley, had become massively successful. Clare, as Cynthia knew her, discovered a strange particle that mutates a human body into becoming larger and lighter and air, effectively turning them into balloons. It was also an aphrodisiac that worked. Once Clare had figured out a way to let people inflate and deflate themselves safely, she had become a multimillionaire, able to rent out small islands, hobnob with celebrities, and basically do whatever. Cynthia, meanwhile, whiled away her days crunching data and fixing code for broken apps in her studio apartment.

Cynthia got a few days off. She was curious about the so-called Finley Particles. She was up for doing something new, considering she had never undergone this strange transformation. When she contacted Clare about it, not only did she agree, but Clare also wanted her to go along with her on a “field test.” She and Clare would go to Clare’s personal resort, inflate themselves, go for a float and all that. Clare said no one else would be there, just the two of them. She also said the outfits they wore would expand with them, so she wouldn’t get naked. All this, and expenses paid.

It still felt weird stepping outside of a hotel wearing only black panties and a black, sleeveless, strapless tube top. The panties were like gym bloomers in that they covered the whole ass, not that there was much left to the imagination. The tube top covered most of Cynthia’s cleavage, which reminded her how between the two of them, Cynthia was the top heavy one, while Clare was the bottom heavy.

Clare waited for Cynthia outside. They were dressed similarly, save for a black smartwatch on Clare’s left wrist. Cynthia never saw Clare so exposed before. “Top of the morning,” Clare said with a smile. “You remembered to tie your hair up like I asked.”

Indeed, Cynthia’s pink hair was in a ponytail, reaching to the top of her shoulder blades. Of course, pink was not its real color; Cynthia didn’t much care for her somewhat light brown hair. Despite being the same height as Clare, one could easily tell them apart since Clare maintained a wholesome appearance, free of tattoos, piercings, nail polish, and other modifications. Cynthia, on the other hand, sported a unique color of nail polish on each of her fingernails and toenails, as well as a number of black ink tattoos on her body, most notably on her forearms and lower back. Normally, she had piercings throughout her face, but today, she only wore her earrings. (Three for each ear, and not just the lobes!) Aside from that, she was one spiky bracelet away from being a punk band reject.

Cynthia asked, “So why are we in underwear again?”

“My clients have been asking for skimpier inflatable clothes. We are wearing the prototypes.” Clare spun around on her heels, no doubt flaunting her wide hips. “Right now, they are female only, but given that about 70 percent of my clients are cis women, that took priority.”

“Do I have to do anything?”

“No, but if at any point you feel uncomfortable, just call my name. I’ll fix anything that might go wrong.”


“You’d be surprised how finicky the particles are.” Clare tapped the screen on her watch. “Right, I’ll go first.”

Clare’s smile grew wider. It was so strange how when Cynthia first met her in college, how they bonded over math and old video games, how back then, Clare never smiled, while Cynthia always did. Ever since Clare found those particles, it was like she finally knew true joy. That became evident when Cynthia saw Clare’s thighs growing thicker. This was soon followed by her once flat belly expanding, then by her breasts swelling into a larger, rounder shape. Her arms blew up too, along with her smartwatch. Looking at her was like seeing a cluster of balloons inflating.

Clare got rounder, thicker, plumper, and to Cynthia’s surprise, taller. Clare’s limbs stretched out farther as her tits and belly grew in height and width. Her nipples were poking through her top, growing larger and wider too.

Sure enough, like Clare said, her underwear expanded with her. Both top and bottom matched the ever-growing proportions, and with every passing second, her cameltoe bulged more and more. Clare giggled. “No matter how many times I do it, I always feel so elated.”

Clare had become about three feet taller than normal. Her tits were wider than Cynthia was. Her butt could function as a sofa. Despite this newfound girth, she lifted off the ground. She continually performed a breaststroke with her cannons for arms to keep going back down toward the ground.

Cynthia didn’t want to say it out loud, but she wanted to rub Clare’s ballooned belly, not just with her hands, but with her feet and cheeks too. Cynthia didn’t normally feel this sort of attraction to Clare, but something about her giddiness and her feminine plumpness was driving Cynthia’s mind wild.

“Okay, now it’s your turn. Remember, if you feel tingly, that’s normal.” That was the real reason Cynthia agreed to this; Clare claimed these balloon particles could give massive orgasms. She said some of her customers can only get off when they inflate. Clare said it’s her favorite kink.

Clare pushed buttons on her smartwatch. One moment, Cynthia felt nothing. The next moment, she felt like she had a huge breakfast. She felt the urge to burp, but nothing came up, just a greater sensation of fullness. The world appeared to be moving up. Before long, that feeling of fullness spread to her legs, then her arms, then chest. Her heart beat rapidly. She felt her cheeks flush. Her breathing hastened. She felt her belly protruding outward, further and further by the second.

“Fascinating!” Clare said. “Your tattoos are growing along with the rest of you.” She was right. Cynthia had a black ink tattoo of a spade on her right wrist. It was larger than ever before, yet somehow still in perfect proportion, even as it and her arm ballooned before her very eyes, and very rapidly.

Cynthia was bloating faster than Clare did. It took Clare about four minutes to turn into the giggling plump balloon she currently was. For Cynthia, it felt like two minutes, and she was already about the same height as Clare.

“Wha-what’s going on?” Cynthia asked.” Why am I getting bigger than you?”

Clare tapped some keys on her smartwatch. “I don’t know! The watch isn’t working!” Cynthia didn’t even notice that her feet weren’t touching the ground until, “Cynth! You’re flying really fast!”

Cynthia noticed Clare drifting away from beneath, though that was hard to notice on account of her ballooning bosoms. She felt wind pushing against her massive form from all sides, caressing her exposed skin. It gave her a massive wide-on.

Cynthia, through no fault of her own, had reached the rooftop of the hotel within seconds. A flagpole on the rooftop carried the Io flag. “Cynth, hang on!”

Cynthia lunged forward, grabbing the flagpole with both hands. She held tight, grateful that her hands were still normal. She saw Clare float near her, her eyes focused on her wristwatch. Cynthia was quickly losing grip as her arms got bigger and bigger, pushing her away from the pole. Her body pulled upward, her toes pointing toward the sky. It took every ounce of strength to not let go of the pole.

“Something’s definitely wrong,” Clare said, observing the still-inflating Cynthia. “Not only are you inflating at max speed, you’ve somehow also achieved negative weight.”


“Well, normally, you become weightless, neutral so to speak, but the app says that places with low gravity are what’s pulling you now. I don’t understand it, but I think I know how to—”

Cynthia’s arms were now so big, she couldn’t bend at their elbows anymore. Her breasts had obscured half of her view. She felt her cheeks fluffing up enough to be visible. Most curious of all was that Cynthia’s pussy was on fire. Everything from Clare’s smooth and enlarged body, to Cynthia’s hair draping over her ever-expanding form made her desperate to cum.

Her palms slipped off the flagpole. Her increasing size and supposed negative gravity caused her to fly upward even faster. She couldn’t see much of anything. Clare was nowhere to be seen. “Clare, heeeeeeelp!”

Clare came up from below, doing breaststrokes, kicking her hammy legs. Even with all that effort, Cynthia felt herself drift up higher, Clare’s serious brown eyes harder to notice. “Clare, heeeeeeelp!”

Cynthia spun wildly about. Her eyes couldn’t focus on anything. She felt like she was flying blind. The bulge in her panties grew tighter by the second. She couldn’t tell if she was going to explode or orgasm first.

“I gotcha!” Cynthia felt Clare’s delicate hands wrap around her puffed up leg along with Clare’s meaty arms. The sensation made her crotch hotter. “I know what the problem is. It’s hard to explain in words, but I know the solution. I need you to hold still…oh, right. You’re too full to move. I just need you to remain calm. I’m gonna squeeze some particles out of you. It won’t hurt, but it may feel a little sensitive.”

Cynthia felt Clare inch up her ballooned form. Clare’s rounded bust and belly brushed against her soft, bubbly ass. She felt a tight, massive squeeze to her left love handle.

Cynthia couldn’t see Clare this whole time. Her massive bust covered by her expanding tube top was all she could see. She only knew it was Clare holding her because her friend’s petite hands still felt the same despite everything; those slender fingers of Clare’s still hugged her the same as before, only this time, it felt good. Not good, great. Better than humanly possible.

Cynthia moaned, not with her mouth, but her throat. She couldn’t help it. She had never felt this aroused before in her life. Now she understood how Clare made a fortune. Good thing Cynthia was single at the moment; how could she explain to a partner that she had inflated sex with her bestie from college?

Cynthia felt Clare inch her way up Cynthia’s massive back. Once again, Clare’s inflated softness pushed against her. Huge arms snuggled Cynthia’s puffed belly from behind, those gentle fingers embracing her once more.

Cynthia heard Clare breathing deeply, deeply like Cynthia was. Her face was hot. Her whole body was hot. Her mind was gone. All she felt was sensation. Sensation of a real good fuck. Sensation of overwhelming pleasure bursting all throughout her engorged body. Did she really have this much lube in her? Was that what she was inflated with? It didn’t matter. No coherent thought was possible in Cynthia’s mind, only ecstasy.

Not long after, the cumming stopped. Her breathing steadied. She felt the wettest pair of panties she had ever worn. Not only that, she could see more of the world. As she was cumming, she noticed her tits shrinking. Everything felt like it was retreating back to a familiar form. Her limbs didn’t feel immobile anymore.

Clare floated in front of Cynthia, face similarly flushed, a witness to her orgasm. At least now she was the same size as Clare. Funnily enough, her bust was bigger than Clare’s, while the dark-haired mogul’s hips and ass were bigger than Cynthia’s, just like with their “normal” bodies.

Clare tapped buttons on her smartwatch. Not long after, Cynthia felt the fullness subside, her body reverting back to its normal shape. She saw Clare deflate before her very eyes, shrinking down in width, height and depth. Then all of a sudden, they stopped deflating. They were still larger than normal, but not like before. They were “only” about a foot taller, their bellies only modestly plump, their arms and legs only mildly inflated.

The clouds became farther away. The two got closer to the ground by the second. Clare swam toward Cynthia. The two of them floated downward next to one another. Clare said, “The test is over. It appears I fixed whatever was glitching your Finley Particle synthesizers. Tell you what, when we touch down, we’ll get some clothes on, we’ll hit up the bar, and everything will be on me.”

As Clare was saying that, Cynthia spotted a shiny stain at Clare’s bulging crotch, one visible despite the black underwear. “I heard you breathing heavily a minute ago,” Cynthia said. “Did you…”

“I did.” Clare’s flushed face looked away. “It was just the particles. I…I don’t feel that way about women, not like you.”

“Um, Clare, uh, when you held me just now, that was…that was really, really hot, like whoa girl. No one’s ever made me feel that way.”

“Oh, um, I can’t, uh…”

“You know, um, what you’re attracted to isn’t always set in stone. It can change over time. And, well, more women than men identify as bi, if I’m anything to go off of.” Cynthia chuckled nervously. With her enlarged arm able to move again, she rested her hand on the back of her head. “So hey, I’m not seeing anyone, and neither are you. If you wanna do this again, just gimme a call.”

“I’ll, uh, I’ll keep that in mind.”

Cynthia grinned. If Clare didn’t outright reject such a proposition, maybe…Cynthia let her mind wander. They were both young. She was only one Earth year older than Clare. They met when they were in their late teens, so they had known each other for about a decade. Clare was the closest she had ever been to anyone who wasn’t a relative. Clare was smart, driven, not someone to get distracted by things like parties. She was cute, even when she was serious. Cynthia was always glad for her success. And now, after such an intimate moment, if Clare came around, what sort of life would they lead? Two girls blowing up in a penthouse, Cynthia having someone to fall back on when business was slow, Clare having someone to bounce off of during hard times.

Cynthia’s feet touched soft blades of grass. She sighed, knowing she was affected by gravity again. Clare, also on the ground, pushed more buttons on her wristwatch.

Cynthia felt like something was leaving her again. She saw herself shrink down, smaller and smaller, until finally her arms were the way they’re supposed to look. She saw Clare deflate back to her normal size. Unlike Cynthia, Clare wasn’t smiling like before once she was back to normal.

Cynthia looked at Clare and said, “Can I say one last thing?” Clare’s eyes met Cynthia’s. “I thought your preggo belly was pretty cute.”

“Thank you.”

She said thank you! But knowing Clare, she was probably just being nice.


Clarissa opened her eyes. She stretched her arms and legs, not in bed, but in the air. She was floating halfway between the floor and ceiling. Her body was inflated to the point that she was about twenty inches taller than her natural body, but could still move her limbs.

All she had on was her underwear and smartwatch that expanded with her. She unlocked her watch and opened the expansion app. She decreased the amount of Finley Particles in her body. A few moments later, she felt her flesh retreat back into itself, shrinking down to a more manageable body, but not entirely. After about 20 seconds of deflating, she shrunk down to “only” being six-foot-one, and slowly descended to the floor. She rotated her modestly plump body right side up just in time to gently land on her petite feet.

Today was an off day. She didn’t have to rush to the bathroom, make any calls, or anything else of that nature. She could stay in the penthouse as her true self.

After brushing her teeth, Clarissa headed for the kitchen. On the way, she saw Cynthia, wearing the same black underwear as Clarissa, her pink hair free. She was floating above the kitchen, her belly a beach ball, her limbs thick and wide, her widened hips inviting a touch. She was eating freshly cooked mac and cheese with arms so huge, she could barely bring the spoon to her mouth. At least her body was upright; she wasn’t trying to eat upside down again.

“Mac and cheese for breakfast?”

“I can’t help it. The noodles compelled me.”

Clarissa went to the coffee maker. She took the mug marked “World’s cutest CEO,” and filled it with a dark roast. She added half and half along with some sugar. She took a sip while marveling at Cynthia’s delightfully blimpy body, and how the girl could eat so much in her current state. “I see you’ve let your hair down, in more ways than one.”

“The benefits of being my own boss,” Cynthia said in-between her noodle devouring. “Oh, don’t pretend you weren’t looking forward to today. Your mouth says one thing, but your eyes say another.”

They both laughed.

Author's Note: 

Just when I thought I had run out of ideas, I came up with one more. I remember introducing a character named Cynthia in my first story. Now she gets to be an inflatee! But now I am burned out. I don't know how else to write any more of these without rehashing myself. Thank you to everyone who read my stories. I know they're not for everyone, but I am proud of them. You can also find my stories on my Deviantart account, under the name aigis-tan. Goodbye, and as always, stay freaky.

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