# Returning The Favor

By: TheDragonBoy

## Content

“Come on Dipper! You’re gonna love it!” Mabel insisted.

Dipper looked at his sister uncomfortably, “I don’t know, Mabel. I mean the stuff we’ve been doing already is weird enough, but this would be, like, a whole nother level…”

The Pines twins had been engaging in some… less-than-wholesome “fun” lately. It had started as just a one-time request from Mabel, a private fantasy involving a certain size-changing flashlight which she had asked her brother to help bring to life, but since then she had convinced her brother to help with her urges on a number of occasions.

“But it’ll be fun! Trust me,” Mabel pleaded.

Dipper rubbed his arm nervously as he thought. What his sister was suggesting would definitely go beyond anything they had done so far; at least before he could say he had been doing it for Mabel, but he wouldn’t be able to use that excuse if he went along with this one. Mabel, seeing she was about to lose him, took on a more sincere tone.

“Look, I know you’ve been doing this all for me, and I know it’s been… awkward, but that’s why I want to try it this way so much, so I can- you know- return the favor.”

Dipper looked his sister in the eyes. She knew him too well; how had she managed to turn something like this into a favor for her?

“Ugh, fine!” Dipper conceded.

“Yes!” Mabel cheered, “You won’t regret it, it’ll be great!”

She quickly dove under her bed and slid the now familiar flashlight out onto the floor, but rather than come back out, Dipper heard her grunt a few times as she struggled to pull out something larger.

“It’s been under your bed this whole time? I thought Grunkle Stan got rid of it,” Dipper asked.

“I guess he wanted to hold onto it, ‘cause he just stuck it in the attic closet,” Mabel replied as she finished pulling the object into the open. Dipper made a mental note to check under his sister’s bed later in case she was hiding any other weird things there.

Mabel got back up, flashlight in hand, and kicked open the roll of fabric that she had brought out with her. The old shag carpet unrolled onto the attic floor, and she jumped onto it, rubbing her bare feet excitedly. She looked up at her brother, who still stood there nervously.

“Come on, Dip, aren’t you at least a little curious?” she asked, reaching out her hand.

Dipper tried to hide his blush- he had been trying not to think about his own feelings toward the idea, but admittedly he was kind of curious; he was a boy of mystery after all. He reached out and touched his sister’s hand. A bright light flashed and the two of them were thrown apart, landing with their backs on the carpet.

The twins groaned in unison as they sat up, rubbing their heads. Dipper looked himself over- or should I say herself? (Nah, too confusing). It had worked, he looked down to find he was now wearing his sister’s signature shooting star sweater, along with the rest of her clothes… and the rest of her body. Looking up again, he saw his body sitting up in front of him, of course now it wasn’t him, it was Mabel.

Here I am again, he thought, thinking back to their previous body-swap adventure, but this time he was going to be doing a lot more with his sister’s body than just impersonating her.

Knowing what was to follow, Dipper took a moment to focus his attention on his crotch. He could already feel his familiar appendage missing from between his legs. He tensed his muscles experimentally, and felt the strange cavity that extended into his core as it contracted. If felt wet, agitated, almost hungry.

“Alright bro, let’s do this,” Mabel encouraged.

Eager as always, Dipper thought. He lifted his hand with the magic flashlight and pointed it at his possessed body. He flipped on the light and Mabel grinned as she was shrunk down to just a few inches tall, the lower half of her borrowed body disappearing into the carpet. She looked around, taking in all the new details she could make out in the individual carpet fibers, and then she looked back at Dipper. From her new height she could easily see up her own skirt as he sat with her legs parted in front of her.

So this is what Dipper gets to see, huh? she asked herself. She looked up to her brother’s face, signaling him to continue.

Dipper sighed, an extra girly sound given the circumstances, and put a hand to his waist, fitting his thumb behind the elastic bands of his skirt and underwear. He pushed, shifting around on the floor as he guided the fabric off his new butt and along his new legs, and Mabel watched her familiar white panties approach as her brother undressed her body.

Dipper slipped the garment off onto the carpet and looked down. At this point, his sister’s privates were something he was almost used to seeing, but not from this perspective. She always waited until he was tiny before she undressed, so he never really saw anything at his normal size. The slit seemed so small, so innocent now that he was looking down at it. Was this really the same opening that had swallowed him up? That had squeezed him almost within an inch of his life, just for the pleasure of the sensation?

He became aware of a sort of tingling sensation playing over his borrowed insides, growing stronger as he thought things over. That stuff is… ‘turning me on’? he thought, Is this how Mabel feels when she thinks of this stuff? Curiously, he reached down and placed a finger lightly on his slit. He saw the skin tense up slightly, just like it had the first time he had touched her with his shrunken hand, but inside he could feel the small series of contractions that followed the contact- a hidden sign of Mabel’s lust, buried within, behind the walls of her skin.

Suddenly, Dipper realized what he was doing- touching himself in his sister’s body! He jerked his hand away and looked over at Mabel, hoping she hadn’t seen, but what he saw was even more shocking. Mabel had his pants down around his knees, with one of his hands feeling sensitively around his boyhood.

“Mabel!” he yelled.

“What? I give you my vajayjay to use and I’m not even allowed to touch your wiener?” she retorted.

Dipper wasn’t exactly comfortable with that logic, but he didn’t feel he could really object given the circumstances. He watched her awkwardly for a moment as she felt up and down his member, the shaft growing harder and longer as she continued.

“Alright already! Can we just get this over with?” Dipper insisted.

Mabel marveled at her borrowed prize for a moment longer, and Dipper began to wonder if the real reason behind all this wasn’t just so that his sister could find out what it was like to have a penis. But then she looked up at him, her characteristic grin seeming oddly out of place sitting on his face.

“Okay ‘sis’, here I come,” she called jokingly.

Mabel ran towards her body, leaving Dipper’s pants and underwear behind and pushing the carpet fibers out of her way as she went. Dipper watched as she fearlessly approached her own oversized labia, now under his control. She looked up at her body with a satisfied expression, reaching out and placing a hand firmly on her exposed crotch. The skin tensed up again and Dipper could feel the cavity beyond contract once more, just a bit harder this time.

“Whoa, calm down there girl,” Mabel said, seemingly more to her loaned loins than to Dipper. She carefully pushed open one of the lower lips, exposing the familiar red flesh beyond.

Wow… it’s so big inside, she thought. Let’s see how Dipper likes this.

She lightly placed a hand on his inner wall, and slowly, very slowly, began to brush her fingers down its length. Dipper felt the toes of his current body curl as his fingers gripped at the carpet. He moaned lightly. Just as Mabel thought, he was totally unused to the feminine pleasure, fresh and sensitive, this would be like his first time. She got a devious idea which she couldn’t resist.

“Brace yourself, Dipper!” she called just as he was coming back to his senses. Mabel raised a hand all the way up and plopped it against the little knob of flesh that just barely peeked out from the parted lips. Dipper felt his sister’s entire body spasm, suddenly and violently as he lost his breath in a single sharp exhale. Along with the lustful contractions of his privates, he also felt something else contract, something a bit more familiar.

Mabel gave a short scream as she was suddenly blasted with a stream of off-yellow liquid, sending her back onto her butt and knocking the hat off her head.

“Ugh! Dipper!” Mabel complained, wiping the smelly fluid from her face.

“It’s not my fault!” he complained, “I don’t know how to control anything down there! And what the heck did you just do anyway!?”

Mabel got back on her feet. That’s what I get for trying this without going to the bathroom first, she thought.

“That was just the beginning,” she replied, “Just try to keep my *ahem* other excretions on the inside.” She watched her butt cheeks grow taught in front of her as Dipper got the message, squeezing her other opening tightly shut.

Even though she was now in Dipper’s body, knowing that the urine she had just been soaked in was her own somehow made it less gross, and knowing she was about to be soaked in bodily fluids anyway made up for the rest. So she tried to move past it and walked back up to “her brother’s” lower lips. Being a bit more careful this time, she spread open one of the folds and started rubbing the slick interior once again.

“Woooow, Mabel, this is amazing,” Dipper moaned.

“Told you so,” she said jokingly.

Mabel probed just a bit deeper and Dipper moaned louder. She smirked, knowing she was just barely scraping the surface of what was to come, and that even with his experience, she didn’t think Dipper had realized it yet. She expanded her reach until she was massaging the entire rim of her borrowed kitty, watching excitedly each time her fingers grazed over her clitoris and caused the strong rhythmic contractions that she was so used to feeling from the inside.

Dipper was utterly speechless. Is this what Mabel feels like when I do this? No wonder she’s always so eager! I’ve never experienced anything like this! He felt waves of pleasure surging up into his body as Mabel expertly drew her fingers along his slick interior. He was amazed at how confident she seemed, sure she must be much more familiar with this area than he was, but she was in complete control of him, even at her tiny size, he was at the mercy of her touch.

After a while, Mabel noticed the contractions growing a bit softer and decided it was time to get to the main event.

“Alright Dipper, I’m going in,” she called, stretching his lips wide open. She took a good look inside, it was twitching quickly with his pulse and dripping wet with his fluids: ripe for entrance. “Try not to let me get pulled in all the way. I’m not sure what’ll happen,” she called.

Dipper felt a streak of fear run through him, unsure if his sister had been joking. Does she really expect me to be able to control this?

He didn’t have time to get an answer, because just at that moment Mabel plunged his body into her budding slit. Dipper practically screamed in pleasure, she had gone in even faster than he had the first time. Her entrance alone had caused him to contract so hard that she was already halfway down her tunnel.

“Mabel!! Be careful in there!” he yelled. He couldn’t hear any response, but he felt her hands slide up over his slick insides, pressing her fingers deep into his folds. His vagina pulsed hard several times, and he could feel it growing firmer and even wetter. Is this her idea of careful!? he thought, his body too tense to speak.

Inside, Mabel was trying her hardest not to laugh. The way she was making her brother squeal was more than gratifying. She felt at the walls of her vagina, walls she had felt over and over as a part of her being and on the tips of her fingers, now in Dipper’s care but still very much under her command. She felt them squeeze her, and though the grip was tight she took pride in knowing just how much pleasure she was giving.

That’s when she noticed the throbbing between her legs. Of course, how could she forget her piece of the deal. She could feel Dipper’s penis pressing up against the wet folds around her. She pushed her hips into the vaginal walls and moaned lightly herself as she felt the slick flesh fold around her borrowed member. She started rubbing back and forth, eliciting more contractions from the flesh around her as her penis started to pulse in time.

“Mabel! Are you seriously doing what I think you’re doing in there!?” Dipper called. He could feel the form inside him shifting in a very particular pattern. “You can’t do that in there! Don’t you know what’ll happen!?”

“It’s my vagina and I can do what I want in here!” she called back, not sure if he could actually hear her. Either way, there wasn’t much he could do to stop her. The contractions of Mabel’s tunnel had brought her further in than Dipper could possibly reach, and her constant movements spurred his pleasure on and on with no sign of stopping. Though he was more than a little worried, he couldn’t deny that he was loving every second of it.

Another hard contraction sent Mabel even closer to the core of her loaned body. “I hope you know what you’re doing Mabel,” Dipper managed before he finally gave in to the urges of her body, his hands snapping down to his pulsing entrance as he felt a pressure starting to build toward his climax. All the while he could feel Mabel moving in time, pushing him on his way to the big finish.

Finally a huge spasm shook his whole body, pushing him to cry out one last time. He could feel his interior walls squeeze harder than he ever had before. He felt Mabel, in his body, being pushed hard against the far end of her vagina and for a sickening moment he thought she would pass clean through, but then he felt himself starting to relax as the climax passed.

His body went limp as every muscle unwound, allowing his sister to slip from the slick outer lips along with a trickle of overflowing fluid. He felt her slide out from his entrance as he lay with his back to the floor, his juices undoubtedly staining the carpet between his legs.

“So? How was it!?” Mabel called, remarkably only a little winded after the ordeal.

“That… was… incredible…” Dipper answered between pants.

Mabel, of course, had already been able to tell from the inside that she had done a great job, but she still wanted to hear him say it. She took the opportunity to brush a hand across her temporary penis one last time, now thoroughly deflated. Sure, she had wanted to feel what the other end of the experience was like, but she hadn’t been lying when she’d told her brother her main reason for all this.

“Just returning the favor,” she said.

The twins laid there for a few more moments as Dipper caught his breath. “Could I- you- have really gotten pulled in all the way?” he asked.

He heard Mabel laugh a little. “Dipper, if you could get sucked into my womb, you’d have been in there a while ago.”

Originally Published: 2-Jul-2018