“Wait, you’re just going to leave?” Gale sounded surprised, perhaps a little upset.

“Sure? We both came out ahead today, I think.” Derpy was experiencing an entirely more placid emotional high than just minutes ago. Her new flesh always seemed particularly alive with sensation after new growth, as though the added mass of glands was dutifully signaling that it was eager to add to her endless bounty.

Derpy did a little twirl in the middle of the room, snapping out her wings to keep her balance as she felt the familiar bounce and jiggle of her bosom, but also, wondrously, something similar from her enlarged butt. Additionally, her wider hips, probably still modest in a town full of earth ponies, felt huge to the once lithe pegasus. She sighed in satisfaction, as no doubt Berry would do her the favor of exploring Derpy’s new dimensions. With a shrug, she made for the back door.

Gale followed her out and immediately made a grab for Derpy, firmly redirecting her in a direction that would lead around the building to the much more public space in front of the store. “I don’t think we’re done yet. Sure, I look amazing now, but that’s just a side-effect to what you wanted. You were just messing with me out in the store, and I think I deserve a little payback.”

Derpy had no problem with their direction, or being seen topless in public. Quite the opposite. And with the remains of her old garment in hand, she carried proof that she hadn’t intended to be indecent, a medical emergency had put her in that position. Obviously. Frankly, most of Ponyville took her in stride by now. “If you wanted sex you could have just said so.”

“I want to see some evidence,” Gale declared.

The calm contentment Derpy had been enjoying was blown out like a candle. She stopped in place. “What?” Warning tingles made themselves known deep within her endowments.

Gale faced her with a hungry smile. “You talked a good game in there, and you certainly looked pent up, but all I saw was a little squirting, a little dripping.” She leaned closer. “I made my choice, but did you trick me into it?”

A reasonable request, Derpy agreed intellectually. Certainly the mare didn’t need that new bit of doubt in her life. She would have been glad to demonstrate somewhere secluded. Unfortunately, all her tits heard was that someone who’d already been blessed by them still doubted their capabilities. Derpy’s nipples twitched, milk started running down the slopes of her boobs to drip to the ground or soak into her pants. “And this needs to happen in public?” She tried not to sound eager.

Gale scoffed. “What if Mr. Rich and everyone else is just humoring your wild fantasies? Just the crazy tit lady. They’re probably glad you know how to put on pants.”

No. No! Derpy’s neighbors did humor and indulge her, but they never doubted her capabilities. Her boobs slowly grew firmer once more, apparently of the opinion that a reminder wouldn’t hurt. Besides, Gale was likely just trying to rile her up, as though Derpy couldn’t do better herself.

And do better she would. Derpy raised her hands to the sides of her boobs and fiercely grabbed a handful of flesh each, not without effort. She’d equated her astounding tits with natural disasters which might be averted by appeasing the relevant goddess. But Derpy had been merciful and patient, struggling to control herself even before it was certain that she would receive her due.

The pleasure of her own rough handling drew a moan from Derpy and she leaned against the wall. “Ladies,” she tightened her grip, shivering. She’d need something extraordinary, out of proportion even with Derpy’s size. Something that would mark witnesses forever. Every moment not given to conscious thought should bring her mind wandering back to Derpy’s breasts and their milk.

“Are you about to start masturbating? Is this happening?” Gale’s earlier fierceness seemed brittle.

Derpy’s proud breasts were eager, so eager to put this girl in her place. Already the current, pitiful flow of milk turned into forceful spurts, arcing all the way across the narrow alley behind the store.

If only ponies could know what Derpy saw in her future. They looked at the mailmare, the huge, brazen tits she flaunted, and assumed she’d peak sooner rather than later. Perhaps they thought she was some unlikely aberration, more cow than mare. They thought so small. Even Gale, who’d been gifted a beautiful transformation, wouldn’t allow herself to believe fully. Why couldn't they be like Berry, who apparently just assumed that Derpy would never stop growing, would be immortal just to have more time to grow?

On lazy afternoons when their daughters were napping, curled up against Derpy while she leaned against a lightly dozing Berry, Derpy would listen to the industrious hum of her glands, audible only to herself. In quiet moments like these, she knew the truth of it: That there would always be more of her, more, beyond her current ability to grasp. That there would never be a time when her family had to face a world with less of her love, her breasts and her milk in it. Perhaps Berry had it right and Derpy simply had never thought of it.

She tried to imagine herself ten years down the line. Her breasts each three, maybe four feet across, her upper body, probably her hips, entirely obscured by the largest milk factories in the world. Every time she landed on her mail route, her uniform would struggle to contain the ponderous bounce and jiggle of her vastness. Her nipples might be as big as her fists or more, capable of dispensing truly absurd amounts of milk every second.

Maybe one day the mere presence of her obscene glands, their sheer, monstrous fecundity, would change the world around her, young mares having six, eight, even ten foals at a time, all would grow strong from Derpy’s milk, a population explosion sustained by her tremendous tits, each generation more fruitful than the last, spreading across the world as heralds of her expansion and the promise that one day, no creature on this world would ever go hungry again.

She’d barely stuck her hand down her pants to finger her sopping slit before she came with a moan, her wings snapping out before they joined in on stimulating her bosom with the tips of her feathers.

They were beautiful fantasies of a future yet out of reach, but today, as small and limited as she still was, Derpy wanted to achieve something Ponyville would remember years from now, no matter her growth in that time. Her nipples were achingly hard, her breasts impossibly firm.

For once, Derpy was not playfully struggling to hold back the release of her milk until a moment of her choosing, she was demanding the best her breasts could provide, the most her body could withstand. She started sweating profusely as her rack grew uncomfortable warm.

The previous churning returned, louder, more forcefully, almost growling. Derpy was dimly aware that the other mare took a step away. Her broad areolas seemed to bulge outward slightly, while her skin creaked and groaned, tasked with containing a catastrophic deluge. Her overburdened jugs started to pulse bigger, however briefly, before returning to their previous size. A dull ache made itself known within her breasts and Derpy got the most peculiar feeling that they were pressing down on themselves, struggling to prepare ever more milk for dispersal in the same space. They grew perceptibly heavier.

“Always holding back,” she mumbled, breathing heavily. “Raising the kids ...is more important. But today …hfff... today’s gonna be good enough ...nng… for a creation myth.”

“What does that even mean??”

People need a glimpse of the future.

Despite the mounting discomfort, Derpy came again as before her eyes, her breasts bulged larger, not the usual smooth growth, but in fits and starts. There was none of the wholesome sense of rightness she’d come to associate with the growth of her flesh and the glands within that came as a reward for feeding ponies, just overwhelming pressure as her body was forced to expand from within, more and more of the milk she normally called on from parts unknown being forced into her physical form. What little release provided by the fluid leaking and spurting from her currently was meaningless in the face of it.

“It’s time,” Derpy declared, stumbling forward even as her great rack continued to creep larger against the protests of her strained body. The world seemed to recede from her, all that mattered was the aching need for release, and the knowledge that she'd never output enough to keep pace with her production.

Emerging onto the square in front of the Barnyard Bargains caused the eyes of every passing pony to zero in on her glorious, naked breasts, the effect rippling outward like a wave. The immense pleasure of having so large an audience caused her another climax, she missed a step, staggered, kept walking.

“Are you alright, dear?”

Derpy had been just about to open the floodgates for good, but the blue cupcake mare was kind, she gave her stallion proper credit for not openly staring at the mailmare’s astounding rack and forgave him when he faltered without resenting Derpy. She deserved consideration.

She sort of vaguely gestured behind her. “There’s … an unbeliever,” she explained, aggrieved.

The other mare looked Derpy’s current company over, brow furrowed in confusion for several moments before she understood. “You’ll just have to make Ponyville proud, then.” Her expression fell immediately, maybe she hadn’t wanted to admit that their hometown had little to distinguish it except for anxiety about Everfree monsters and Derpy’s intimidating boobs, unless one happened to be obsessed with apples. The blue mare strode off briskly towards the store. Derpy chose to allow this.

Ponies were staring, some more openly than others, but they weren’t yet gawping in helpless awe. Derpy finally allowed herself release, the thin, irregular squirts of her milk uniting into two mighty torrents. She was rocked by another climax before frowning briefly. Her range was too short, the unnatural weight of her breasts forcing her fat nipples to point downwards. Her milk frothed and churned in an expanding puddle a few feet in front of her. She doubted any other creature in the region could gush so forcefully, but she resolved to do better, using both of her arms to hold up her bosom, her output arcing away into the distance.

It was a tiring pose, and the twin pleasures of sweet release and a large audience flooded her mind with unparalleled bliss. Derpy laughed, was interrupted by her own sloppy moans, laughed again. She allowed her breasts to fall, they were still too taut to properly slap down against her stomach, instead nearly toppling her forward.

Ponies whispered and talked, indistinct, irrelevant. Delirious with sheer ecstasy, Derpy wandered this way and that, mashing her tits together, tweaking her nipples, demanding more of her breasts. Her output escalated, and Derpy felt she should compensate by leaning forward as though walking into a headwind.

She fell forward, braced herself on arms numb and uncoordinated from the sensations washing the edges and distinctions off her thoughts, then landed on her tits, still so damnably tight. It should have hurt, it might at some unimportant future point, but everything was pleasure now. She felt herself continue to grow and came again, crying out from the awesome feeling of her grotesque output redoubling again and again and again.

She spent a few moments at the center of a growing white puddle before struggling to get up. She slapped her palms against her expanding jugs, still gushing without end, pausing only to spend a few seconds to think fondly of Berry, who knew her breasts so well. She experienced a pang of regret on noticing that the ponies around her were keeping their distance. She tried to grab handfuls of her terrifyingly productive titflesh, but it barely yielded under her fingers. The sensation of weight was tremendous, but the main reason Derpy had to use her wings to assist in dragging herself to her feet was how huge and bloated her rack was, she couldn't squeeze them together between her arms to support herself on them.

I'm built to have huge tits.

Derpy was certain that her current size, the girth of her tits nearly twice what it had been that morning, would be temporary, an escalation of fullness and engorgement. Additionally, Berry Punch preferred the normal feel of her breasts when they weren't so stuffed and eager for release. She couldn't quite see how those two facts connected, but they were important.

Just as Derpy was about get solid footing to wander off again, she heard it. Barely capable of coherent thought in her current state, she couldn’t make out what the ponies around her were saying. But there were the first strains of reverence in the murmurs, the first notes of dawning understanding.

Derpy collapsed into a heap, splashing back down into a growing lake of milk and rolled onto her back, moaning lewdly. She kneaded her boobs fiercely as they sprayed, milk raining back down on her. "I'm still full!" She called out in a moment of lucidity, giggling at the absurdity of the situation. "Do you get it? T-tonight ... hff ... I'll have more milk than this morning!" Her back arched as she came again. In that moment, she wanted Berry to be right. She wanted to live forever, to make her endless milk available to everypony's children and grandchildren. To experience pleasure like this whenever she cared to. She wanted whole generations to grow up taking her milk entirely for granted.

The last vestiges of her awareness were washed away in white pleasure exploding from her abused nipples and arcing through her body like lightning as Derpy realized that her current audience understood. Ponyville needed never to fear hunger again. Droughts, ruined harvests, harsh winters all rendered irrelevant by her limitless resources.

Derpy’s next clear impression was the sound of Berry Punch’s voice and a large, yet gentle hand on her shoulder. She found herself sitting on the rim of the basin below the statue of a rearing earth pony, facing inward and milking herself into the water in great, irregular spurts as she tugged lazily at her nipples. She’d been staring into her own cleavage, now again roughly the size she’d earned in the back room of Barnyard Bargains, and contemplated her superlative abundance. Derpy did tend to lose track of time, doing that.

“Time to get you home, Derps,” Berry suggested kindly. “I think your latest conquest left, probably didn’t wanna get drafted to clean up milk above earth pony reach.” She carried a large towel slung over her other arm, which she used to gesture at a nearby building, marked by some streaks of white. "Or maybe didn't want people asking what she said to you," the mare added thoughtfully.

Derpy hadn’t exactly flooded the town, but she liked the think that she sheer force of her lactation, and the fact that the volume she’d spread about was far more than a mare of even her size should ever be able to create or store was finally burned into the minds of her neighbors.

“The kids?” Always her first thought after pulling herself together. Derpy believed in having fun for herself regularly as self-maintenance, but it was still in service of her family. Her back and wings were damp, so apparently she really had just lain there and milked herself until she'd been at the center of a lake of her own making. Some brave fool must have approached and helped her up to guide her to her current location at some point.

“Tops is watching them. Them and dinner. Put on a pot of lentil and potato stew.” Berry smiled. “You really gave them something to think about today, yeah?”

Derpy winced as she stepped onto dry ground. “I think my nips are gonna hurt all week, Berry.” She accepted the towel and covered herself. “Was a bit uncomfortable, in general.”

“You don’t gotta top yourself anytime soon,” her partner suggested. “Let the townsfolk be happy every time you don’t put in an effort, yeah?” Berry never seemed particularly invested in Derpy’s growth, but knew what to say, more often than not. “Even when you get bigger, they can wonder what’d happen if you tried this hard again.”

Later, in the darkness of their bedroom, Derpy enjoyed Berry's closeness and warmth. "Should I be worried?"

Berry lightly touched her hand under the covers. "Hm. Could you be?"

Derpy couldn't help but giggle. "About boring things, sure. About me? I don't think so. Everything is so amazing, Berry. I wish you could just spend one day in my body."

"Tell me about it." It was a familiar game. Talking about Derpy's boobs openly somehow made them even more enjoyable, and Berry readily went along with it.

She could hear Berry adjust her position to face her. Derpy sighed happily. "They're so heavy. And they got even bigger and heavier today. But it only feels good. Great, even." Even now she felt their weighty presence on her chest. She took a deep breath. "Like I'm built to carry huge boobs. Gigantic ones. And my hips got wider! I've always been a bit jealous of you on that front."

"Mmh." Berry's touch brushed across the side of Derpy's breast.

"And the milk!" Derpy's large nipples grew erect, waiting only for her command to start gushing once more. Fortunately, after the day's entertainment, they waited patiently, for now. They were still sore, which was quite extraordinary. Her beautiful breasts hadn't provided anything but pleasure in recent years. Still, it was oddly comforting to know that her flesh found limits before her productivity did. "Today was incredible." She rubbed her thighs together. "It w-was a drop in the bucket!" Even the memory of that euphoria was beautiful.

"I just wonder why," she muttered dreamily.

"Why?" Berry sounded genuinely curious, because Derpy hadn't been in the habit of questioning her gifts.

"Why, why do I still feel all that milk I'm not using?" Just thinking about it, Derpy felt as though an enormous liquid weight was pressing down on her thoughts for just a moment. "I tried so hard today but ... I can't share my milk faster than I'm producing it. I'm never gonna be able to use that reserve. And there's always m-more." She moaned the last word, her arousal spiking with the acknowledgement of the impossibility.

"Huh." Berry shifted her weight, then went back to gently rubbing at Derpy's breast. The tender ministrations served to soothe rather than inflame Derpy's lust, and both mares enjoyed the act. "I guess you'll just have to be immortal so all that milk doesn't explode into being and flood the country once you kick the bucket."

Flood the world.

Derpy rolled her eyes. "You're always such a pessimist." Warmth pulsed from her breasts reassuringly, as though to tell her that Berry's scenario was impossible.

"Maybe," Berry allowed. "But whether it's real or just a trick of your boob-obsessed brain, you can just take it as a constant reminder of what your jugs already did. What they'll keep doing."

Forever.

"They are pretty impressive," Derpy agreed, taking a moment to enjoy the slow waves of pleasure flowing between her crotch and her boobs without urgency. "I feel so ... so full of life. So fertile." It was a pleasant feeling, although she had no intention of getting knocked up again. While having huge tits and being surrounded by countless ponies who enjoyed her milk was a nice fantasy, she'd prefer if all those ponies were the responsibility of someone else.

"Heh. You want more kids?"

"Hm." Derpy's breasts throbbed eagerly. "Boobs are telling me I could feed ...any number. But honestly, I'm okay with never changing a diaper again."

"I'd just as soon never be pregnant again myself," Berry stated. "I'm just gonna forge ahead. We could adopt?"

Berry had always been very poor at establishing emotional connections with other ponies and their daughters hadn't been exceptions to that rule. It had taken time for Berry to grow to love them, so the suggestion was quite unexpected to Derpy.

"I'm listening."

"We make a pretty good team, yeah? I think we could take care of an older kid. Someone who needs emotional support not, y'know, babying." Berry chuckled. "You were the first pony who made me feel you wanted me around. Me, not the big goon who knows how to shank people. I think giving that to a teen would be a win all around. Except, y'know, for the baggage, but you handled me alright."

Derpy cuddled up to Berry, squishing her breasts against her lover. "I'm not against it. Let's talk more later." She was pretty sure if she hadn't had the opportunity to be emotionally nurturing to the other mare and their two daughters, Derpy would be a very different mare right now. Although having Dinky might have been what triggered her awesome boob powers, so maybe that thought was moot. If she weren't doing right by the ponies closest to her, it'd be a different sort of mare living in her skin.

She enjoyed the idea of providing a home, a sense of belonging to another pony, tho she was curious how a young teen might react to Derpy's proclivities. Her growing notoriety might not appeal to a prospective adoptee, and Derpy assumed that older children would have the final say whether a permanent arrangement suited them. A period of fostering would answer those questions, she supposed. If she was honest with herself, more ponies who'd see her as a person and not just a huge pair of tits would also be welcome once Derpy reached ever greater sizes. Both perspectives were necessary at different times and from different people.

Life was good and getting better. "Good night, Berry."

"G'night."

Author's Note

I have hamfistedly set up the presence of Amethyst Star in future fics.