It was still early in the morning when Sofia left home for her usual morning jog. Since graduating from high school, it had become a habit for her to start the day with a run around the neighborhood.

She had been looking for some part-time jobs in the meantime but hadn't been lucky enough to find a good position with a stable job. Therefore, physical training filled her days when she wasn't out with friends. In addition to soccer team practices, she often went for a run or did weight and bodyweight exercises at home.

A different story, however, applied to Sofia's older sister, Carla: she was always the smart one, excelling in academics, and had been attending university in the city for a few years.

However, she had a lazy and indifferent attitude toward anything other than studying and her interests. She spent most of her time at home when not studying or hanging out with friends – a way of life so contrasting with her younger sister that Sofia couldn't comprehend. Wasn't she getting bored at home? Didn't she ever feel like moving her body and staying in shape?

"What a shame" Sofia thought to herself "The brainy one in the family is currently nothing more than a rubbery blob squished between my boobs", with every stride of the run flattening Carla even more and removing any hint of the third dimension from her body.

Sofia chuckled as she reached the park's fountain, which marked the turning point of her run. She stopped to drink from the fountain, enjoying the coolness of the water after the exertion of the run and admiring the morning-lit landscape around her.

Deciding to take a break before heading home, Sofia rummaged through her cleavage and pulled out her squished sister's body before it got stuck to her chest (again..).

Carla's body, previously spherical, now resembled a CD with a diameter of a few dozen centimeters and a thickness of a few millimeters. It was considerably convenient to hold. The front of the Carla-CD displayed one of her eyes and miraculously her mouth, freed from the mess that was her body.

"Hey, big sister, how's the run going? Are you comfortable?" Sofia teased. "Haha, very funny" replied the CD's mouth. "I admit I might deserve it after last night, but could you please let me go when we return home? I have an exam coming up, and I need to study all day."

"But listen to the demands of this little disc!" Sofia mocked, squeezing and tightening Carla's body, causing her protests. "And here I was thinking I had finally found a new yoga mat..." she said, looking at her squished sister with a predator gaze.

"All right, the shenanigans have gone on long enough. I guess we can call it even" said Sofia, prompting a sigh of relief from Carla.

"Thanks, siste... mppff" replied Carla, just before Sofia's palms clapped together, folding the two-dimensional body of her sister on herself. "As soon as we get back home, of course! Come on, we still have half the run left!" declared the runner, stuffing again the squashed body of her sister between her boobs, and restartinge the run with renewed vigor.

The flattening and squashing of Carla's body were not over for the morning, and given the trend, it was becoming even worse.

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Arriving home, Sofia pulled her sister out of her cleavage and, after a brief moment of considering reneging on her word about freeing her, she tossed her sister's small, thin body onto the couch, where she knew it would take no more than a few minutes to return to normal. Carla had a talent for these things, inexplicably.

Meanwhile, Sofia went to take a shower to wash away the sweat from her run. She took her time, as she didn't have any particular commitments for the day. After getting dressed with black short and T-shirt, she returned to the kitchen to find Carla back to normal, enjoying breakfast, with an extra cup of cooffee for her younger sister.

"A peace offering" she said, with a mouthful of jam-covered bread.

"Thanks, much appreciated" replied Sofia, sitting down at the table and starting to drink from the cup.

"How's university going? It's been a while since we talked, now that I think about it."

"Nothing your big sister can't handle, of course" said Carla, puffing out her chest with deliberately exaggerated pride. "The exam I have in a few days is tough, but I should be well on track with studying" she continued, taking another bite of her bread.

"How about you, with the job search? Found anything interesting?" Carla asked, but Sofia looked away, staring at her cooffee and starting to pour sugar into it. "Well..." replied the younger sister in a subdued tone, "I've done some part-time jobs, but nothing I'd like to do permanently."

"On the other hand" Sofia resumed, raising her voice again, "our soccer team is doing really well! We could aim for winning the championship this year! In the last match..." The footballer's eyes sparkled with enthusiasm, and Carla was forced to endure her sister's account of the team's previous victory, with a less than enthusiastic expression on her face.

"Wow, I almost prefer being squished between those two melons of her rather than listening to her games again.." thought Carla, who had little interest in anything that involved physical exertion for herself or others.

"Anyway" Carla interrupted at one point, "Mom and Dad aren't coming back until the weekend, right?"

"Yes, but they left meals ready in the fridge" replied Sofia, a little annoyed at being interrupted at the most exciting part. "They reminded us before they left, but you were probably lazing around at that moment."

"Hey! Even the world's best scientists need rest to recharge their brains!" replied Carla, pointing her index fingers at her temples. Meanwhile, she had started to clear the table, confident that if she had left the task to her younger sister, breakfast dishes would have remained on the table all week.

"Okay, it's been an interesting morning, but now it's time to start studying. Allons-y!" said Carla, leaving the kitchen and locking herself away in her room.

Sofia remained alone in the kitchen, sipping from her cup. "And now what?"

************************************************

Boring.

Boring.

BORING!

Sofia lay upside down on the couch, holding her phone. She had tried to contact her friends to meet up, but no one was free that day. After yesterday's training and this morning's run, she didn't feel like exercising again, and she didn't particularly feel like going anywhere either, let alone looking for a job. And now, what would she do all day?

A mischievous smile spread across her face: there was always Carla, her favorite rubbery toy. They had agreed to call it quits, sure, but hadn't she just said she was making good progress with her exam? Would one less day of study really make a difference? And she was getting bored, so the decision was made.

Sofia sprang from the couch to the kitchen, where she grabbed the plastic bottle in which she had stuffed her sister the day before. She had done it so many times that she had become super efficient at stuffing her in it: head, shoulders, arms, and then (unless she felt like having fun watching her sister's bodyless legs run around like a headless chicken) slowly the rest of the body.

Once she had the bottle, she headed to Carla's room, moving slowly to make as little noise as possible. When she reached the door, she noticed it was slightly ajar. "Looks like she forgot to close it, better for me" thought Sofia, opening it quietly.

Sitting at her desk with her back to the door and headphones on, Carla was studying, unaware of the world around her, especially of the girl at her door who intended to stuff her into a plastic bottle.

Sofia took her first steps into the room, but before she had even reached halfway, she heard a BEEP coming from the floor beneath her. Looking down, she saw a laser beam from a photocell interrupted by her bare foot.

"Oh, sh..." Sofia realized an instant before the section of floor she stood on was catapulted upward, crashing heavily into the ceiling with a resounding WHAM!, squashing the girl and making her disappear in the middle.

The loud noise made Carla turn, removing her headphones and admiring the success of her trap: a section of the floor had been brought into contact with the ceiling by a huge spring, slowly bringing that section back into place.

Attached to the ceiling was what looked like the cutout of the back of a girl in black shorts and T-shirt, barefoot, legs and arms arranged in an X shape; Sofia's boobs had been most affected by the flattening, increasing in size and resulting in two circular bodies protruding under the girl's back, despite being squashed from behind.

"I knew you were up to no good, so I took some precautions" gloated Carla, getting up from her chair and admiring her sister's ass from below. "Now what? You've proven that I can't study in peace if I let you roam free, so I'll have to keep you busy somehow" she said, when she noticed Sofia's plastic bottle on the ground. "Really, the bottle again? You really have zero imagination when it comes to squashing, little sis!" Carla announced, with an almost disappointed expression on her face.

"First, let's get you down from there" said Carla, taking the spatula she had brought to the room in advance to prepare for that exact situation. With a bit of elbow grease, Sofia's body detached from the ceiling, and Carla found herself holding her younger sister's flattened body in her hands, studying it with an analytical eye.

"This time you're all squishy, huh?" said Carla, examining Sofia's flat body, particularly her boobs, which were even larger due to the flattening (so much so that they overflowed from the body's outline), and touching the lower part of Sofia's belly, left exposed by the impact.

"Sometimes when you get squashed, you become as rigid as a cardboard cutout, and other times you become..." she said, crumpling Sofia up like a piece of paper, reducing her to a mess of body parts roughly shaped like a baseball. "...soft and malleable like a sheet of paper."

"I wonder what the deciding factor is" Carla pondered, holding Sofia's crumpled body in one hand, still studying it with a critical eye. "But I guess those are questions for another day" she concluded, unfolding her body and flinging her like a sheet, causing her to return to the previous flattened shape, albeit with her body all wrinkled.

"Now let me show you what can be done with a little ingenuity" said Carla, with a far-from-reassuring expression as she menacingly loomed over her younger sister's helpless body.

*****************************************

In the late afternoon, Carla continued undeterred with her studies, alternating her attention between paper books, notebooks, and her tablet. However, on her desk, unlike before, there was a new lucky charm, which diligently observed the girl during her study session (not that it had a choice, actually).

It was an origami in the shape of a small T-Rex dinosaur, which Carla had obviously composed using her sister's malleable body, but in a different way than one might expect: Sofia's face formed the tail of the dinosaur, with one eye on one side of the tail and the other eye on the other side.

Sofia's arms formed the dinosaur's legs, and symmetrically, her legs had been folded to form the small arms of the T-Rex. The body of the origami was mostly formed by Sofia's boobs, which, due to their huge size (relative to the rest of the body, of course), covered much of the surface. Finally, the head of the dinosaur consisted entirely of Sofia's ass, covered in black shorts.

Overall, the origami gave the impression of great confusion, but also great precision in having so perfectly wrongly associated Sofia's body parts with those of the dinosaur; Carla was very proud of it and often looked at it with a smile throughout her study session.

During the day, she had tried various types of origami with her sister's body, from a swan to a dragon to more abstract shapes, but this was definitely her favorite.

Sofia, on the other hand, after recovering from the impact with the ceiling, found herself in a decidedly uncomfortable and confusing situation, which prevented her from making any sound or movement: she could only watch with her eye turned towards the desk her older sister concentrated on studying.

"You'll see, big sis" she thought to herself. "After your exam, we'll settle the score..." After all, returning the favor was the fairest thing to do. Wasn't this, after all, sisterly love?