Caityln (Patreon)

Jeff’s life hadn’t been the same since his mother remarried. Most kids living in blended families would say so, but most kids didn’t have a stepsister like Caitlyn.

Jeff’s mother May had married Caitlyn’s father Bill the summer after Jeff finished high school. He was all set up to start classes at the community college in the fall, and suddenly found his life invaded by an absolute bombshell of a stepsister.

Caitlyn was two years older than Jeff, a few inches shorter, and had the best boobs Jeff had ever seen.

He’d met Caitlyn’s mother of course, who was a pretty fair knockout herself, but the tit fairy must have skipped a generation, because Carol was no more than a set of nice C-cups at best.

Caitlyn, meanwhile wore a 32F. Jeff knew this because he’d dug through the laundry basket when Caitlyn and his mother were out shopping and his dad was at work. He didn’t do anything weird with the bra, but he’d spent some ‘alone time’ in the shower that afternoon.

But there was even more than that. As if the gods weren’t cruel enough to have given the nerdy, never-had-a-girlfriend Jeff a stepsister with breasts the size of cantelopes, she was also a stone cold stunner.

Her breasts we’ve already covered, but Caitlyn also had arms that were lithe and soft. Not overly muscular but carrying none of the fat that decorated her décolletage. A narrow waist with only the barest hint of healthy pudge. Hips that spread the exact width of her shoulders, and an ass like two ripe hams, just begging for a good slap or to be grabbed, a cheek in each hand.

And that was just her body.

Dark brown hair fell in waves over her shoulders and danced across her bulging breasts whenever she moved. Thick dark eyebrows angled up over her eyes as if about to make a questioning quirk at any moment. Big brown eyes that were like an abyss Jeff could get sucked into and never return. A perfectly-sized button nose that turned up at the tip ever so slightly.

And her mouth. A perfect, plump little bow that was never without a layer of pink lipstick or lip gloss or whatever. Jeff didn’t know. All he knew was he wanted wanted to feel those lips on several parts of his body.

Now, you might Jeff’s situation was pretty bad. But it turns out things were even worse than what you’ve heard so far. Not only did the 18-year-old self-professed ‘boob man’ suddenly find himself frequently in the same room with the most exquisite pair of breasts he’d ever seen in real life. But they were still growing.

How it was possible that a woman of almost 20 was still developing, Jeff didn’t know. He was not an expert on such things but all the information he could find online said breast development should have either stopped, or slowed to be near-imperceptible by now.

But it wasn’t imperceptible.

Jeff could see it happening.

Caitlyn split her time between the two families. Every other weekend she stayed with his mom and her dad, and the rest of her time she spent with her mom in the city were she was going to college.

Whenever she stayed with them, it seemed like Caitlyn spent all her time eating.

May was eager to earn her stepdaughter’s affection, and had found the quickest path to that affection was through Caitlyn’s stomach.

“These waffles are the best, May. Could I have a couple more?”

“You always make such good Mac and Cheese, May!”

“May, that casserole smells amazing! I’m going to grab one of these delicious rolls to take the edge off. I might try to eat the whole pan otherwise! Ha ha ha…”

This was how it was every time Caitlyn came to stay with them. Jeff used to do his homework in the kitchen where there was plenty of table space, but the sight of his sexpot stepsister gorging herself, with crumbs dusting her rounded cleavage, proved too distracting. Next he tried the living room, but the sounds from the kitchen made his imagination run wild and he got even less work done. Finally, he had to stay sequestered in his room whenever his stepsister was snacking.

Jeff was surprised that Caitlyn wasn’t more plump, considering how much she ate. When they all sat down together for dinner she’d put away twice what he did, and then stick around for hours after Jeff and Bill left the table, hoovering up any potential leftovers with her pefectly straight white teeth.

Over the course of the semester, Jeff watched his stepsister grow and grow. He never got another chance to check her underwear but he was sure she must have gone up at least a size or two since the summer ended. Then one night his ‘mystery’ was solved.

His stepdad was in his office, video chatting with Carol.

“No Bill, she can not spend Thanksgiving with you! We have a schedule.”

“But it’s what she wants, Carol…”

Bill sounded completely whipped by Caitlyn’s mother. What had his mom ever seen in such a pussy?

“Of course it’s what she wants! That trophy wife of yours does nothing but stuff her with food!”

“It’s just how they bond, Carol. May is a very nurturing person…”

“Nurturing… that’s a good one! That woman is ‘nurturing’ our daughter right through the alphabet!”

“I…”

“Do you know every other time she stays with you I have to take her bra shopping?”

“Er…”

“I’ve had to buy her new shirts and blouses at least five times since you got married, because whenever she stays with you she eats her way out of all her tops!”

The conversation continued, but Jeff quickly retreated back to his bedroom. In his mind’s eye he recalled dinner the last time Caitlyn had stayed with them, the busty brunette shoveling down an entire pan of meatloaf by herself while the rest of them split the second one. There were a couple slices left in their loaf when Jeff escaped to his room that Caitlyn had presumably eaten as well. Jeff imagined the food passing those flawless pink lips and plopping down into her scandalously small tank top, the tanned honeydew melons within inflating larger and larger as she filled them with calories.

Jeff wondered if he should take up baking. Maybe he could win his pneumatic stepsister’s affection with cookies the way his mother had with meat.

A week before Thanksgiving, Jeff knocked on the door to his stepsister’s room.

“Hey Caitlyn? I’m testing out cookie recipes before Christmas, you want to try some?”

***

It was Christmas Eve, and Jeff’s mom and stepdad had gone to bed wine-drunk hours ago. Jeff and his stepsister were watching Christmas Vacation for the fiftieth time. He sat in a recliner while Caitlyn was curled up on the couch, munching on the cookies from the last in a stack of empty platters.

“Jeff?”

“Yeah?”

“Come over here.”

Jeff rose and took a few steps toward the couch to sit at the other end.

“No, stand over here.”

She pointed at the floor in front of her. Jeff did as she commanded.

“I really appreciate all the extra… ‘treats’ you’ve been making for me.”

She laid one hand on each watermelon size breast.

“They’re really tasty…”

Caitlyn pressed inward, making already long line of cleavage bulge up in her neckline even further. Caitlyn was wearing festive holiday pajamas, but while they were baggy over most of her body, the snowman-printed flannel covering her massive chest was skin-tight.

“I wonder if there’s a way for me to show my appreciation… Why don’t you come have a feel at the… ‘effects’ of your hard work?”

Trembling from head to toe, Jeff stepped closer, and leaned down, hands outstretched but hovering inches away from the blessed orbs.

Caitlyn rolled her eyes briefly and grabbed his hands, pressing them into her overgrown flesh. Still his hands did nothing but shake slightly. With each passing moment he felt himself gain confidence though.

Experimentally he pressed both hands inward. His stepsister inhaled sharply with a soft moan.

He squeezed the delicious glands and felt the firm elasticity press back against his fingers. Caitlyn was purring like a cat now, the sounds in her mouth seeming to come from deep in her core.

“Oh, Jeff… that feels so good…”

Jeff brought his hands around to heft both breasts from below, squeezing them together and letting his hands drift toward their fronts.

“They’ve gotten –mmm– sooo much more –ahn– sensitive lately…”

Jeff’s thumbs were about to find their prize, when Caitlyn’s moans stopped.

“Too bad were family now.”

Jeff pulled his hands away as if they’d been burned.

“And we can’t do any of the stuff a brother and sister wouldn’t do.”

Her tone was haughty and condescending, and Jeff stared at the floor.

“Well, I know one thing a brother wouldn’t do…”

Her tone had turned into teasing, and Jeff looked up again, confused.

“A brother wouldn’t hand-feed cookies to his sister on Christmas Eve…”

Jeff glanced at the still mostly full platter, and the stuffed belly pressing against the pajamas below the horizon of Caitlyn’s cleavage.

Caitlyn seemed to read Jeff’s mind and heard his unspoken question, and she rubbed her bloated stomach through her top.

“I still have plenty of room left, Step Brother. You wouldn’t want all those cookies to go to waste, would you?”

Jeff was trembling again as he moved in slow motion toward the cookie platter.

“Don’t worry about my big tum Step Brother. I’ll digest all these cookies tonight and use them to grow my boobs even bigger.”

Jeff was starting to sweat.

“You want my boobs to get bigger, don’t you Step Brother? Isn’t that why you’ve been making me so many treats?”

Before Jeff could protest, Caitlyn opened her mouth and pointed toward it with her finger. Jeff held out a cookie for her to take a bite.

—

Epilogue

Jeff really hoped Bill and his mom were asleep. He knelt on the living room floor and slid Caitlyn’s pajama bottoms off. Grabbing his stepsister’s hips, he slid her further down on the couch, and lowered the waistband of his own pants, letting his rock hard member spring free.

Glancing up at her, Jeff saw that everything from his ribcage down was blocked from her view by two spectacular mounds of tanned skin. Her pajama top was completely unbuttoned, and her breasts stood high and proud on her chest, sinfully swollen with countless calories provided by her step family.

“Go on Step Brother… put it in.”

Fumbling around below her line of sight, Caitlyn found her prize and brought Jeff’s tip to her lower lips.

She whimpered.

Jeff slid the head in slowly, making Caitlyn moan softly, then as she stretched around his modest girth, she got louder.

Caitlyn was reclined almost horizontally on the couch, clutching the nearby throw pillows as Jeff slid the last inch of his modest length deep into her.

“–Uhn!– Oh yes!”

“Sssh, you’re gonna wake them up!” Jeff whispered.

“Better –hmm– put something in my mouth to keep me quiet, then!” She said with a wicked grin.

Jeff straightened his back, lifting his stepsister’s hips up off the couch, and grabbed a square of chocolate peanut butter bar to stuff in her mouth.

Her hips bucked as he began thrusting rhythmically while she chewed. Her pelvis rose and fell as he moved and Jeff was entranced by the way her breasts undulated like ocean waves. Every time she swallowed and opened her mouth to moan again, he was ready with another treat to keep her tongue occupied.

Caitlyn used one free hand to rub her taught stomach and the other to squeeze one fat nipple. Jeff felt her body tense and her vaginal walls clamp down on him as she moaned despite a mouthful of peanut butter bar. He came moments after she did.

Jeff wasn’t sure if his stepsister’s moans were for herself, his cock, or his baking, but after several minutes, when their panting breaths returned to normal, she cupped one enormous breast and looked over at him, asking the question that was in his mind…

“More?”