Rainbow's Magical Boobs

by Holocron

Rating: mature
Tags: Anthro, Romance, Original Character, Porn, Fetish, Rainbow Dash, Random, Sex, Profanity, My Little Pony: Friendship is Magic, Alternate Universe
Length: 4098

Rainbow Dash has been trying a formula to help enhance her chest, but the results end up being more than she anticipated.

Rainbow Dash has been very, very insecure about her chest for the longest time. A rather ironic concept, given how much pride she puts into the rest of her. And while her alicorn lover, Green Thunder, loves her no matter what she looks like, the mare wants a bigger chest. Thankfully, a solution came in the form of a new, strange shake mixture. After waiting seemingly forever for it to arrive, Rainbow has it, and is going to give it a try.

Contains: Hyper Boobs, Breast Expansion
Commissioned for blaa6
Derpibooru: 3351303

Published 2024-06-10 01:00:02 UTC
Last updated 2024-06-10 01:00:02 UTC

It has Arrived!

Rolling out of bed with an annoyed grumble, Rainbow Dash slumped her way over to the shower, the faint snoring of her lover echoed from the bed behind her. Getting in the shower, the mare let the hot water wash over her. From her rainbow hued mane, that flowed over her head and down the rest of her body. Rubbing and scrubbing along her hair, the mare grumbled slightly more, getting more of her exhaustion out of her. Once her mane was all cleaned up, she went to clean and scrub her body, and this is where her frustration only grew.

Rainbow’s body was petite, and this was only a generous description of her body. Her slender, athletic figure was certainly the envy of more than a handful of mares, but this was because of her job as a Wonderbolt. She was always a skilled flier, and her body reflected this. But this was also the problem that brought an annoyed furrow to her brow. Her figure was too athletic, and she hated it. Her hips had some slight curve to them, but at best her ass was only a smidgeon about flatness. But it was her chest that brought out the most ire from the pegasus. Rainbow hated how small her tits were.

Unlike her friends, Rainbow had barely visible breasts, only a small bump that at least showed others that she was a mare, but that was as big as they seemed to get. Rarity and Applejack, who were very modest in her endowment, had bigger boobs. Fluttershy being her closest comparison, but even she was about twice as big as the pegasus was. And this brought her to Twilight Sparkle and Pinkie Pie, who didn’t have boobs, they have massive milkers and bouncing knockers. Rainbow’s mind seethed in her envious, jealousy frothing at the mouth as she cursed and grumbled under her breath as she cleaned herself out.

Following her shower, Rainbow had barely gotten to start cooking her breakfast, when she heard a knock at the door. Her ears perked up at the sound, her lips curling into an excited smile as she dashed to the door. So fast and focused on the guest at the door, Rainbow failed to notice, or care that she was only wearing a bathrobe that just barely covered her body. Opening the door, the first thing she saw was a brown paper wrapped box, with a pair of tits just barely held in a package carrier’s uniform pressing on it.

“Morning, Rainbow Dash.” Derpy Hooves, the mailmare, greeted her with a goofy smile. “I got a special package for you.” Rainbow would’ve normally pouted angrily seeing the mare’s superior chest, but the box caught all her attention. “Please sign here for it.” Rainbow immediately grabbed at the package, signing whatever the mare handed her before all but slamming the door.

“Finally! It’s here, it’s fucking here!” Rainbow panted, almost manically laughing a little as she made her way back to the kitchen. “I’ve been waiting weeks for this!”

Opening the package, Rainbow’s eyes gleamed as she saw what looked to be some box of a powdered drink mix. Giggling through her smile, she quickly grabbed a nearby tall glass, filled it with water, and set it beside the box. Opening it, Rainbow glanced through the instructions, only to discard them as she poured more than a few spoonfuls of the contents into the glass. Stirring it, the clear liquid mixed and churned until it was a light brown, then a dim yellow, and finally a pale, pinkish color.

“That should do it..” Rainbow said to herself, pulling out the spoon. Lifting the glass, she sniffed at the contents. It had a soft, almost subtle, fruity aroma to it, and tasted just as sweet as she drank the entire glass down in a single, heavy gulp. “Ahh…okay, that should…work?” There wasn’t anything, but then a sudden chill, like a tingling shiver ran down her spine, causing her to shudder a little. But then it settled as soon as it happened. “Okay…anything else?”

“Morning babe, how’s it-” Green Thunder, Rainbow’s all green alicorn lover, greeted with a yawn as he stepped into the kitchen. Wearing only boxers, his muscular frame was on full display. As he looked at the mare, his words were cut off as he noticed the box. “Oh? It showed up? Well…how do you feel?”

“I feel…pretty plain. I tingled a little, but nothing else.” Rainbow replied, looking at herself over and over again. Her long mane swayed and flowed about as she checked herself out. “What do you think? Does anything look different?”

“Hmm, let me see…” Green commented, humming a little as he walked around his marefriend. Taking a hand, he smacked her ass. “Soft, lovable ass…” He gently ran a few fingers through her mane. “Long, flowing, beautiful, rainbow mane…” And then was in front of her, planting a gentle kiss on her lips. “And soft, perfect lips. Nope, I don’t think anything’s different. And you know I love what you have already.”

“Well, aren’t you sweet?” Rainbow smirked, kissing him back. “But that’s not what I’m asking. Are my tits bigger?” Green only shook his head. “Urgh…okay, it’s fine, it’s fine. I’ll just go on a jog. Maybe it just takes a few minutes to kick in.”

“Yeah, maybe you’re just so awesome, that it needs to adjust to you first.” Green playfully chuckled, smacking at Rainbow’s ass as he walked behind her. She let out a small moan, only to turn to look at him. “What? You liked it.” Before she could respond to him, he pulled her into a romantic, deep kiss.

Rainbow’s body shivered as she felt not only the warmth of her lover’s lips pressing harder against her own, but the way his strong arms wrapped around her, hugging her so close to him. Her body shivered as she felt him not only pull her against him with one arm, which was drifting down to fondle her ass, but his other hand was rubbing gently, almost stroking along her incredibly long mane. Rainbow playfully rolled her eyes, she knew how much Green loved her mane. Still, she moaned a little more, wrapping her arms around him too as she savored this romantic moment between them.

“There, feel better?” Green playfully teased, pulling away to see the somewhat embarrassed blush on his marefriend’s face. He chuckled. “I thought so. We just need to be patient, that’s all.” Rainbow only grumbled again, making the alicon smile. “Alright, come here.” He pulled her into another loving kiss.

Daily Progression

Day 01
So Green told me I should start keeping a note of any changes that happen. Telling me that I’m not gonna notice if I just keep talking about it all day. He’s lucky he’s cute…and a sweetheart…~~and has that really good dick~~…Anyway! So far, nothing has happened, and my tits haven’t gotten any bigger. The shake also has a weird aftertaste, like not in a bad way, but I drank it like an hour ago, and I can still taste it. Either way, I’m gonna just have to keep my eyes on my chest, as if I wasn’t doing that already. Green also said that maybe some massage should also help, but I’m sure he just wants an excuse to feel me up…~~not that I’m gonna say no, he’s got some real good hands~~…

I don’t think what I’m doing is wrong, and it’s not like I’m using magic…I think…to do this. ~~But I swear to fucking Celestia, if these shakes don’t work, I’m gonna fly to whoever makes them, and shove my entire order right up their ass!~~ Anyway, this means a lot to me. I’ve always been the most athletic pony around, but lately, I've been wondering what it would be like to have a more, um, noticeable presence. And while Green tells me that he loves me no matter what I look like, I know he's a stallion. Alicorn or not, he's a stallion, and I know he would love to see me with a pair of juicy, fat tits! I assured him it's perfectly safe and won't interfere with my flying. But it’s whatever for now, I’ll just have to be patient. I hate this.

Day 02
Not much to report yet. I had my second shake this morning before practice. Well second shake this morning. I think I'm supposed to only take one in the morning, but given how nothing has changed so far, I might as well just take more. Surely, there's no harm in that. If anything, shouldn't drinking more at once make it work faster? I'm still feeling like my usual speedy self. I think my wings might be a bit stronger, though! Could be my imagination. I keep checking the mirror, but I don't see any changes yet. Patience, Dash, patience. Green has still been pretty supportive, even telling me my chest is getting bigger, even if I can't see it. Still, I'm gonna keep trying these shakes. Maybe I should try three in the morning?

Day 04
Okay! So I might be starting to see a tiny difference. My chest feels a bit fuller, but nothing major. I asked Green about it, and he said the changes would be gradual. Still, I decided to ask some of my friends about it. I avoided Twilight and Pinkie. I just don't want them to know until I have a little more of a bigger rack. Fluttershy was pretty supportive, but told me I should be patient. And thinking back, I think I'm still smaller than her. Rarity didn't seem to notice anything, even when I was practically shoving my tits in her face. Too busy with some fashion show, or something. I stopped listening when she started rambling about whatever it was. Thankfully, Applejack noticed. She said I seemed more energetic today, which was awesome!

Maybe this shake is giving me a boost in more ways than one. I've been considering taking even more before I go to bed. Right now, I'm going through a lot, but if doing this much gives only this much progress in a few days, I'm gonna need to really step up to get results before I'm some old mare! I do feel a little bad taking more than I probably should behind Green's back. He's been telling me to be patient, and I'm telling him I'll try. But I just can't keep to this slow ass speed. I'm a mare of action, a mare of speed, and I just want some results that actually matter.

Day 07
Holy, fucking, sweet Celestia on on a cloud of hot fucks! It’s working! My tits are growing! Yeah, I was drinking these shakes a lot, multiple times a day, but it only just started showing real progress now. They’re…fine…I guess. I’m just happy to finally see some progress. It's definitely happening. My chest is more pronounced now. This time, I tried to see if Rarity would notice. She mentioned that I look different but couldn't quite put her finger on what it was. I just had to leave at that point. I was just trying to see if she would notice, and I guess she did, but it still didn't feel like it was enough.

I've also decided to keep these shakes a secret for now. I don't want everypony making a big fuss. Since Applejack tried to tell me to be happy with what I was born with. Easy for her to say, she's got a decent pair of tits! I still haven't told Twilight and Pinkie about anything, even to see if they'll notice. Last thing I need is miss egghead overreacting to me drinking shakes to grow my boobs. And I definitely don't need that giggling, pink pile of boobs throwing a party for me over it; not yet anyways. But I can't help feeling a bit impatient. I keep checking myself out, hoping for more changes.

Day 09
Over one week down! My chest has grown even more noticeable than before. So that's pretty good news so far! It’s still manageable and doesn't interfere with my flying, which is a relief. I'm pretty sure I could just learn how to fly with bigger tits anyway. I'm awesome! So it would be a cakewalk to change up my style. A small price to pay for having some new, sexy boobs! But I'm not the only one who's noticing. When I was hanging out with her today, I caught Fluttershy staring a couple of times, but she didn't say anything. It's weird, but I feel kind of excited about these changes. I'm still the fastest, no matter what!

Unfortunately, I couldn't avoid running into Pinkie today. And she noticed. My best is bigger than before, bigger than Fluttershy sure, but I'm just about a bit under Rarity and Applejack. But I'm by no way close to Pinkie's fat tits. Still, she asked me if I've been eating a bunch of cupcakes lately. I bet she thinks I've been eating so many sweets, that it's been going to my boobs. If that was possible, I would've had tits bigger than hers by now! I swear, if I ever find out that's how she got so busty. In any event, today went much better than I expected, but now I'm hoping they grow even more now!

Day 12
Wow, these shakes are fucking awesome! My chest is getting large now. It's not uncomfortable, but it’s definitely noticeable. I had to adjust my flight technique slightly, but nothing can slow me down now. I've already beat Applejack and Rarity, and I think I'm almost at Twilight and Pinkie's sizes. In fact, Rarity not only finally noticed my tits were finally getting big, but even suggested a new outfit for me, claiming it would suit my "new look." Guess I'll have to pay her a visit. I’m feeling more self-conscious but also thrilled about these changes.

Still, my chest is now the most prominent part of my body. It's definitely changed my appearance, but I still feel like me. The other ponies have been really supportive, although I think they're all a bit curious. I swear, I think I saw a jealous look on Applejack's face. I’ve never felt this excited about my appearance before! Green's also been very hands on lately too. I barely got through the front door the other day, and his big, strong hands were all over my tits. ~~Oh fuck, I think I'm getting turned on thinking about it.~~ Anyway! I feel amazing, and I can’t wait to see just how big these things can get!

Day 14
Okay, I'll be the first to admit it, but my chest is officially massive. It’s almost comical how big it is compared to my petite frame. I needed help getting through my front door. And as much as I would've loved to not worry about it, Green convinced me to speak to Twilight about this. So I told her everything. And I was right, she was overreacting about it. And when I showed her the box the shakes came in, she pointed out something that I swear, I didn't see. Apparently, the shakes are slow to start, but are supposed to make my boobs grow gradually. And since I drank so many, so quickly, I've been getting a way higher dosage than the box suggests. But there's good news attached to that. Twilight assured me this had the maximum effect and that my body would adapt over time. I’ve noticed a lot of stares and whispers, but no pony has said anything directly to me yet.

Flying isn't a problem either, I've been changing my methods easily, and so it wasn't hard for me to still be the best flier on the Wonderbolts; even though I think my tits are bigger than the rest of me. My friends have been super supportive, with Rarity making me a fantastic new flight suit that actually fits perfectly. She said it highlights my new figure and boosts my confidence; and I gotta say, she's right. I’m happy with the results. It’s a big change, but I feel more confident and unique. Plus, I've proven that no matter what, I'm still the fastest and the best flier in all of Equestria. Now, let's see how this new look plays out at the next Wonderbolts performance!

Two Weeks Later

Two weeks passed, and while the drink didn’t seem to take any immediate effects, but as the days trailed by, her bodily changes were becoming more and more noticeable. It was subtle at first, only seen after a few days, but then her chest grew, and grew, and grew, and grew. It seemed she may have over indulged, but Rainbow didn’t care. Her tits were growing, becoming bigger, absolutely massive. And by the end of the two weeks, she was striding through Ponyville with the biggest smirk on her face. Her boobs had swelled to the size where they could be considered more than twice or even three times her body weight, surpassing her friends, and maybe even rivaling the Princesses in size.

As well as this, her confidence was beyond inflated, taking pride in the stares she would get in town whenever a pony turned their head to look at her. Stallions glanced at her with a mix of curiosity and lust, while mares would glare at her with envy and maybe more than a little curious thoughts as well. Rainbow didn’t care, the only eyes that mattered to her were that of Green’s. Thankfully, her skills as a flier didn’t diminish from her gargantuan tits. Maybe a little slower at first, but being such an expert flier, Rainbow was able to figure out a new way to fly that didn’t get hindered or slowed down by these tits. So now with her Wonderbolt career still soaring, and a pair of beautiful boobs to show off that matched with her long mane, the mare was practically skipping whenever she walked down the street.

Returning home after another pleasurable jog, Rainbow walked in the house, panting a little. Stretching a little, she was amazed at her tits, even if she had to push at them a little to even get through the front door. But there was another side effect, or it possibly was a result of the mare’s growing confidence, borderline smugness. Rainbow was horny, incredibly horny, more aroused than she normally has ever been. As soon as she was in her living room, the clothes came off. The body tight fabric were flung about in all directions, nearly knocking some things over. Green, who was relaxing on the couch, looked up at his marefriend.

“Hey, babe. Did you enjoy your jog?” Green asked, smirking as he knew what was on her mind. “Looks like you’re still pretty pent up.”

“Oh, oh I am.” Rainbow smiled, her eyes narrowing as if devouring her lover’s body. “You…me…bed…now!” Green chuckled, getting up as he was ready for her.

“Fuck, fuck, fuck, fuck, fuck me!” Rainbow screamed out, riding the alicorn’s cock, feeling as he was stretching and filling out her soft embrace. Gasping as she lifted and slammed herself over her lover’s thick size. “You call that…fucking?” She hissed as she was clearly cumming on his length. “Fuck me with that cock! Break my pussy with that fucking…oh fuck!” Arching back, she came, spraying her sweet nectar all over his size.

Laying on the cloud bed, each rippling slam of Rainbow’s perfect ass was making it shake, Green was fucking upwards, loving every second of the mare bouncing on his dick. She was facing him, the body sized tits pressing against him, nearly crushing him as he was throbbing deep in her soaked, tight pussy canal. Reaching up, he was groping, tugging, teasing, fondling, squeezing, and suckling at the mare’s massive tits and nipples. The effect of this drink seemed to no only make her boobs huge, but extremely sensitive when she was horny. And now, she was cumming as her lover was suckling on her plump, soft nipples.

“Come on, come on, come on. Cum for me. Cum in your fucking, fat tittied marefriend’s soaking, fucking pussy!” Rainbow’s moaning and dirty talk pushed the alicorn stallion to keep going. Bouncing harder on this dick, while he was thrusting upwards, she could feel herself getting ready to cum again. “Give it to me, give it to me. I want it, I want it!”

“Don’t worry. You’ll get it.” Green chuckled, smirking as he tugged and squeezed on her nipples even harder. Rainbow gasped and moaned, her eyes rolling back, mouth giving off a goofy, orgasmic smile, and her tongue dangling out from the side of her lips. “Keep moaning for me. Show me how much you love this cock!”

Beating his length in and out of his lover’s pussy, Green’s cock throbbed, swelling as he was going to get ready to cum at any moment. Rainbow’s face was twisted in a pleasurable look, smiling as she panted and moaned. Her tits bounced, smacking, beating down at the stallion the same way his dick was punching deep against her cervix. The feeling was so good, causing her to clamp down on his length, wanting to milk it for as much as he could spare. It had been a while since the two had fucked, and Green’s balls were churning with the hot and heavy load that he was getting ready to pump deep inside of her.

“Keep going, babe. I’m getting close.” Green groaned, looking up at his love with passion in his eyes. “I’m gonna cum. I’m gonna cum right in that tight, sexy pussy.”

“You better…” Rainbow moaned, looking down at Green, though couldn’t exactly see him through her massive tits. “I want it, I want it, I want it.” Leaning over, she was practically smothering him in her breasts as she beat down her round ass faster and harder on his cock. “Give it to me, give it to me, give it to me.”

The two of them were panting and moaning together, pushing the other closer and closer to their next orgasm. The mare’s insides were tightening, her boobs pressing, nipples quivering, all while the stallion’s cock was throbbing, swelling, pulsing, and his balls were tightening against his body. Green moaned out, almost screaming, but the sheer volume of these fat tits was muffling much of the sound as he reached up. Wrapping his arms around his marefriend, he pulled her down as he slammed upwards. Rainbow gasped a breathless scream, feeling as the hot cum was flooding deep inside her pussy.

The warmth filled her, sending a pleasurable shiver down her spine as she quivered and cooed. Green’s cock pulsed and throbbed again and again as he let out more and more of his passion deep inside Rainbow’s pussy, not letting go as her womb was becoming saturated in his hot spunk. Laying forward, the mare cooed, cuddling against the alicorn stallion’s muscular body, loving not only the warm sensation of Green’s cum inside her, but how his strong hands were gently rubbing and stroking along her mane. Laying in their afterglow, the two of them were ready to let the fatigue kick in.

As she rested atop him, Rainbow’s chest started feeling warm. Moaning a little, her tits were almost pulsing as the heat swelled within until it suddenly settled down. Looking down, both her and Green’s eyes widened as the mare’s breasts grew, at least another full cup size. Stroking at her mane a little bit, the stallion’s cock throbbed in her pussy, but seemed to only stay hard. Rainbow’s body was also getting hotter again. Not only that, it felt like she got some energy back, as if she had rested for days, and was not just as horny as she was when she first got home; maybe even more so than before.

“So…wanna go again?” Green asked, playfully teasing the mare as he helped lift her up, pushing his strong hands against her soft tits. Rainbow moaned at his touch, her boobs becoming even more sensitive than before. “I’ll take that as a yes.” His marefriend smirked, feeling the throbbing hard cock still in her cum stuffed pussy, and started shaking and grinding again. “Alright, babe. Let's see how big we can make these babies!”