Published: Sep 6, 2024

My one-hundred and fifty-third caption, commissioned by @Jesurus. Thank you again for your support!

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TransforLife was easily the biggest phone app that had ever existed. Using advanced technology that seemed like something out of science fiction, the app was capable of changing aspects of the user or a consenting third party in incredible ways. While originally built as a machine intended to provide transgender patients with the body of their dreams, the app version had spread like wildfire, allowing people to modify their bodies and lifestyles to their liking. Still, even with the limits, safeguards, and usage tracking built into the app, there were those out there who had learned to jailbreak the app’s functions, allowing them to transform themselves and others into just about anything imaginable. Whether through accidents or malicious use, many people disappeared, never to be seen again…

When Jessica’s sister had invited her into her room to “check something out” one day, she had already begun mentally preparing herself. Kathy was Jessica’s older sister, and had relentlessly bullied her over the years. Given how their parents were always off on business trips, there was no one for the younger girl to really confide in, leaving her stuck with her older sister’s torment. Recently, as the two went through high school and Jessica had developed far more… “fully” than Kathy, this bullying had only intensified. Jealous of her younger sister’s above-average D-cup breasts and sizable behind, Kathy began calling Jessica things such as “fat, lard-for-brains, and cow” around the school to name a few frequent insults. Still, Jessica always took the high road despite her cruelty, never yelling at or berating her older sister in any way despite how much she desired some well-deserved revenge against her.

“What do you need, sis?” Jessica asked, poking her head into Kathy’s room. She was hunched over her desk, using a soldering iron on the back of her phone. “What’s that?”

“Nothing… just a little experiment.” Kathy said with a smirk, pressing the phone’s rear cover back on with a small popping noise. “Remember when I suggested a job working on a farm?”

“Ha. Ha. Ha. I get it, I’m a fat cow. Do you have any original insults? It’s not my fault you haven’t developed yet.” Jessica shot back, crossing her arms under her sizable bust.

With a subtle, annoyed twinge to her facial expression, Kathy took her phone and immediately snapped a picture of Jessica in her casual clothes. Before she had a chance to say anything, a massive gurgle came from her gut, followed by pain and a sense of vertigo. Bracing herself against the doorway, Jessica’s breasts began to balloon outwards even further, tearing apart her shirt as something could be felt brushing against the bottom of them. She pulled apart her breasts and looked down the middle, seeing two more, smaller breasts had sprouted from her chest, straining against what remained of her shirt. Her shorts snapped off entirely as her hips and ass expanded to massive, unruly proportions. Finally, a bushy, bovine tail sprouted from the base of her tailbone as a sack of pink flesh appeared on her belly above her crotch. The transformation finished as her ears reshaped into those you’d find on a dairy cow.

“Holy shit! It actually worked!” Kathy laughed with glee, taking several more pictures of her sister as she grinned ear-to-ear. “Now you’re a real cow, Jessica! Ready for milking!”

“You… you… BITCH!” Jessica shouted in pure, unrestrained anger, having finally been pushed too far. She pounced on her sister, pinning her beneath her new weight. “I’ll show you!”

“G-Get off of me you fat slut!” Kathy cried out as Jessica snatched the phone from her, looking through the TransforLife app on her phone she had just used on her.

“Since you think this is so funny, I’ll make it so you can join me for a little while!” Jessica snarled, pointing the camera at Kathy. “Smile for the camera, you horrible bitch!”

Jessica snapped a picture of her sister, and before she knew it Kathy had begun to shrink, “melting into” her younger sister. Jessica was overwhelmed by the sensation as her sister’s mass traveled through her, ending up in her udders. Moaning out loud with a loud “MOO!”, Jessica’s new udders expanded to a size even bigger than a cow’s. It was orgasmic for her.

“O-Oh m…my God… t-this feels… so… GOOOOOOOOOD!~” Jessica continued to moan, grinding her udder and its massive nipples into the floor beneath her. As she did this, her sister Kathy was dealing with one sensation only: pressure. She felt as if she was holding back a dam, and eventually it became too much for her as Jessica squeezed one of her nipples.

Milk shot out across the room from both of Jessica’s engorged breasts and her swollen udders, soaking the floor and herself with warm, creamy milk. Jessica had touched herself before, there was no denying that, but this paled in comparison to how she felt in that moment, moo’ing like a cow as she desperately tried to squeeze out as much milk as possible.

“Wow… that was… intense…” She said between breaths, her tail wagging uncontrollably behind her like a whip. “I hope you enjoyed that… as much as I did, Kathy.”

Leaning over as best she could, given the massive, beanbag-sized sac that now hung between her legs, Jessica picked the phone back up, which she had dropped on the floor, and opened the app, hitting the reset button. Only… nothing happened. Pausing for a moment, thinking maybe it was just being slow, she hit it again a few seconds later only for nothing to happen again. She began to panic, turning the phone on and off again to try once more, only for nothing to change. Jessica knew something was very, seriously wrong now with this app.

Doing her best to waddle back to her room, Jessica wasted no time calling over one of her friends on her own phone to help. Their friend was very good with phones and computers, and she hoped that they might be able to help her. Coming over as quickly as they could, Jessica’s shy friend, Samuel, was immediately met with the peculiar smell of sweat and milk. Going to Jessica’s bedroom, he could see milk all over the floor, and it didn’t take long for him to finally see his friend, twisted into a cow-like form with monstrous proportions. He was a bit… flustered by her proportions and… exposed features, but he quickly refocused himself, not wanting to view her as some kind of sex object. After listening to her explanation regarding what led up to this, he honestly wasn’t that surprised. He got to work trying to reverse the transformation both of them had gone through, but there was a big, serious problem.

Kathy had jailbroken her copy of the TransforLife app to make such drastic changes to her sister, causing it to become rather… unstable. There was a reason why jailbreaking the app voided the Terms of Service, thus removing all chances at customer support. Samuel did his best, but he wasn’t able to find out why the reset button wasn’t working. With no other options, Samuel helped Jessica down the stairs and took her to his car as discreetly as possible. Once at the hospital, they were directed to a specialist they employed for these kinds of cases.

After dissecting Kathy’s phone, the specialist came to a sobering realization, one they hated telling people who messed around with the TransforLife app: the transformation had become permanent. Jessica and Samuel were horrified by this. Apparently, when two people were transformed at the same time, the original forms were destabilized, and would be permanently corrupted after any major bodily changes. As it turns out, all that milk Jessica had squeezed from herself (and Kathy), was more than enough to seal the deal. Jessica was forever stuck with the cow-life features, and her sister as nothing more than a mass of lactating flesh. Jessica cursed herself for being selfish and stupid, but Samuel reassured her that it wasn’t her fault.

When Jessica and Kathy’s parents learned of what had happened to their daughters, they were both heartbroken and furious. It soon became too much for the bovine girl, and she moved out, thankfully being allowed to live with Samuel instead. The hospital eventually hooked Jessica and what was left of her sister up with a support group for other people stuck with TransforLife transformations. Through them and the personal support of Samuel, Jessica finally came to terms with what happened, choosing to make the best of her new body.

The two would soon move to the countryside and get married, bottling up and selling Jessica’s high-fat milk as a specialty product. Unbeknownst to them, Kathy had grown to love every moment of it, her previously spiteful and mean-spirited mind having become fractured beyond repair, only capable of feeling pleasure and pressure with her new, milky form…