Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/12935880.
  Rating:
      Explicit
  Archive Warning:
      Rape/Non-Con, Underage
  Category:
      F/M
  Fandom:
      Gravity_Falls
  Relationship:
      Dipper_Pines/Mabel_Pines, Dipper_Pines_&_Mabel_Pines
  Character:
      Dipper_Pines, Mabel_Pines
  Additional Tags:
      Pegging, Strap-Ons, magic_sex_toy, Cursed_Sex_Toy, Sibling_Incest,
      Dubious_Consent
  Stats:
      Published: 2017-12-06 Chapters: 4/4 Words: 3122
****** The Pines Twins vs The Rubber Ruination ******
by AlexOC
Summary
     Home alone, Dipper and Mabel explore the locked attic where Stan
     stores old Mystery Shack exhibits. Of course fake taxidermy and
     overpriced bobble-heads are not all the old man has shoved up there
     to be forgotten...
***** Buried Treasure *****
Mabel took a deep breath of musty air and blew hard. Caked layers of dust flew
off the top of the box she was holding, filling the confined space of the attic
and revealing a worn cardboard box. The corners were dented, the tape holding
it shut flaking, and a water stain had ruined the hand written label that now
just said:
"Ma-"
"Toys"
Her brother coughed up the face-full of dust he'd just been blasted with and
twisted his head trying to read the label.
"What-" cough "What is it?"
"Magic Toys? Manly Toys? Makeout Toys?" Mabel guessed jokingly as she set the
box down on the bare wood floor.
Dipper squared down, leaning over the box as Mabel dug her fingernails into the
dried-out tape and tore the lid up. More dust was kicked up and they excitedly
peered through the thinking cloud, eager to know what the box held.
It took less than a second before the box was slammed shut again.
They looked at each other blushing furiously; embarrassed, confused, and more
curious than either of them wanted to admit.
"That was-" Dipper cut himself off mid sentence. "Not what I expected."
Mabel had other concerns. "Why was it purple Dipper?! And why was it so big!
I've seen yours before and they aren't supposed to look like that!"
Dipper blushed a brighter shade of red. They didn't talk about that part of
sharing a room, and they especially didn't talk about his you-know-what.
"I-" He stuttered out. "I'm perfectly normal for my age!"
Oh God, why did he say that?
"I mean that just not based on um... It's for adults you know and I guess some
adults must really like purple." Dipper glanced back down at the box, now in
even rougher shape than before.
Mabel placed her hand on the lid of the box again. "Should we put it back
or..." Her voice trailed off and she left her curiosity unspoken.
Dipper knew her though. "It would be kind of a waste. The store is closed,
Grunkle Stan is out of town, and if he realizes we were up here he might fix
the lock on the attic door."
They nodded together and Mabel inched the box open again.
The box was piled full of strange devices; leather straps, metal buckles,
pieces of oddly shaped rubber, the kind of things kids spread exaggerated
rumors about on the playground. And sitting right on top of them all, resting
gently on a matching purple velvet cloth, was the dildo.
Mabel let her hand hover over it all for a moment and blanched as she noticed
that the purple monstrosity was longer than her entire hand.
Significantly.
That's supposed to go inside someone!
She laughed nervously. "Wow that's a big-".
"-pile of stuff." Dipper blurted out quick. He blushed again. "Sorry"
***** Playing with Rubber *****
Chapter Summary
     They found more than they bargained for, will they handle it with
     maturity or all the grace of middle schoolers?
     And are they prepared for the consequences?
The rain hitting the roof outside was the only sound in the small attic space
above the store. The twins let the silence stretch out as they sat frozen and
studying the contents of the box.
Mabel shifted uncomfortably. "So you didn't want to hear me say 'dick?"
Dipper's continued blush was absolutely adorable.
"It's weird!" He whined. "You're my sister, you're not supposed to talk about
dicks!"
Mabel grabbed the dildo by its flat base and thrust the business end at Dipper,
who hopped back in surprise. "Not scared of them, are you?" She laughed.
"Ew, no." Dipper shouted back, joining in the laughter, as he simultaneously
tried to bat away her attacks and not touch the dick.
The duel was brought to an end when Dipper was able to open up an old umbrella
and use it as a shield. Mabel was forced to admit defeat at the hands of
someone not armed with a sword that jiggled if you wave it too hard.
She leaned against a stack of boxes and turned the thing over in her hands, it
had a set of thin straps hanging of its base. "What the..."
"Hey Dipper." She called to her brother who was still behind his shield,
apparently not sure if he could trust that the duel was actually over. "What do
you think these are for?"
He didn't seem as nervous now and gave it a studying look. "I think yo-" a
grossed out look in his face told Mabel he wasn't exactly relaxed talking about
it either. "I mean a girl is supposed to tied it on like they have their own."
He coughed and quickly gestured downwards.
"WHAT! No Way!" She started sorting out the straps, figuring out which ones
went where.
"What are you doing?" Dipper was sounding nervous again.
"Trying it on obviously." She turned aways from her brother, saving the big
reveal, and tried to center the dick as she hastily tied two straps together
behind her back. "This is going to be hilarious!"
She swung back around the purple protrusion loosely attacked at her waist like
a oversized belt buckle. It bobbed left and right, the momentum of her swing
causing it's rubbery length to whip back and forth.
It was too much and they both started laughing; pushed to the brink of tears
when Mabel places her hands on her hips and thrust them at her brother, causing
the end of the dildo to bounce up and down as well.
Mabel took a step forward readying to thrust her hips at Dipper again. "I'm
coming to get you Dipper."
A crack of thunder shook the roof, the windows rattled and dust was kicked up
into the air.
Mabel felt something brushing against the bare skin of her legs and threw her
hands down to brush away what her mind was already sure would be dozens of
spiders, send scurrying in panic from the noise.
Instead her hand found the straps that had hung from the dildo, alive and
writhing beneath her fingers. They thrashed, and twisted, and darted as she
tried to yank them off in a panic. Every one slipped through her grasp and
wrapped around or between her legs. They grew tight, digging into her and
slowly the dildo moved downwards.
Her heart was pounding and panic filled her chest. What was happening?!
"Mabel!" Dipper cried and he rushed towards her, only to freeze with his hand
outstretched, a horrified look on his face.
Mabel looked down at the pile of shredded cloth at her feet. The crisscross of
straps had sliced through her clothes leaving her naked from the waist down. A
panicked gasping over took her breaths and she looked around the room in
desperation, there had to be a something to get this thing off.
The purple monstrosity shifted a final inch, dragging its cold rubber form on
top of her clitoris. The feeling of a foreign body forcedly manipulating her
down there shocking and disturbing.
She was reaching to grab the thing and tear it off when it stopped.
It stopped moving and pure bliss filled her.
A steady purr took hold between Mabel's legs and resonated up through her,
echoing around inside her head.
Her heart slowed to rhythmic beat, steady and powerful. She was left light
headed as blood rushed to her extremities, every inch of her skin flush and
sensitive. A thin sheen of moisture started to flow from between her legs and
she gently gently bit her lower lip, trying to hold herself back.
She took a deep breath, feeling the rough wool of her sweater drag across her
erect nipples. Exhaling was like a breath of wind carrying everything away; all
the fear and panic, the confusion and reservation. She felt like she could do
anything.
Dipper had covered his face with his hands and turned away embarrassed at her
display. He didn't know how good this felt, how there was nothing to fear in
this much pleasure.
She ran a gentle finger down the length of the "toy" that had changed her
world; somehow she could feel her touch on the rubber and it was good. Not that
she didn't enjoy herself, but if it was this easy she could see why Dipper had
so much alone time.
Her fingers slid off the base of the shaft and unable to reach her clit, Mabel
went lower and lightly fingered herself. She smirked as her deep moan of
pleasure made Dipper jump.
"Mabel please! Something's wrong!" Dipper turned, tried to look at her, plead
with her, but the words fell on deaf ears and he stumbled back as she advanced.
Mabel put a pair of moist fingers on his chest and he froze like a deer in
headlights. Her fingers inched down his torso, pausing only briefly to lift his
shirt and she reached down beneath his waistband.
Her fingers brushed past a scant scattering of hairs and she wrapped her hand
around her brother's dick. It was a bit too long to fit in the palm of her
closed hand and an entirely too normal piece of equipment for a boy his age,
nothing like the thing strapped to her hips. But that didn't really matter, it
was hard and from the way Dipper was squirming he was loving it.
She smiled. "Dipper Pines, you are a dirty boy."
She played with him, rolling and caressing his dick inside his shorts, enjoying
his expression as he tried to stop the little squeaks and moans of pleasure
from escaping.
Her free hand found its way beneath his vest and she forced her tongue into his
mouth in a wet kiss that left Dipper's vest on the floor and Mabel's hand
exploring underneath his shirt...
She was unstoppable, a trail of discarded clothes left Dipper in only
unbuttoned shorts when Mabel pushed him half seated against a box in the attic,
the tent in his white briefs poking through.
She lay her hands against his chest, feeling his heartbeating against them and
pressed him down on top of the box. It was barely large enough for him,
supporting only his chest while his waist dangled off the edge and his head was
only held up by his need to watch her. Hands trembling with excitement she
gripped his shorts in both hands and lifting his legs up in the air, pulled
them off her brother.
His dick practically sprung free of his briefs as she stripped him naked.
Mostly hairless and only a few inches long, it still had a dribble of precum
coming from the half peeled back tip. It was a cute toy.
Not caring where they landed, Mabel threw the last of Dipper's clothes off into
the attic and bore down on him again. She grabbed up his dick and her dildo in
one hand, wrapping and squeezing them together. His skin was burning hot, blood
pounding through it and they moaned together as she pumped her hand. Up and
down, rough, uncaring; she moved her hand with the vigor of someone without
limits.
Dipper moaned, his voice filling the small space, and squeezed hard, holding
them both right on the edge. Her hand was moist as she drew it back, beads of
some strange lubricant had begun to form on the rubber.
"Not yet..." She said. Half teasing, half chiding.
She was enjoying herself, but a sweet tension inside her sung out for more. The
muscles in her abdomen ached longing for release, but it wasn't right yet.
Her eyes roamed the naked, panting body of her younger brother; there had to be
a way to sate her needs, the fire burning in her breast, a hole that needed to
be filled...
Of course.
She pulled back, separating them, and bent her knees just a little, lowering
herself a few inches. Dipper's legs were spread wide and it was easy to find
what she was looking for.
"What are you doing Mabel?" Dipper asked, a nervous, almost hysterical laugh
threading his voice as she leaned down over him.
He flicked as she guided the slick length forward, his cheeks spreading, and
pressed its tip against his taut asshole. She rollee her hips and pressed
harder against him, leaning down over the table and supporting herself with
hands pressed down on his shoulders.
"Something bad." She whispered, barely heard over his gasping breaths as it
penetrated him.
As she penetrated him.
It was better than she'd imagined, the warmth of his body engulfed her an inch
at a time. How he writhed against her, the tightness of him as his insides open
up to her, the expanding and contracting of muscles inside him; each part of it
wrung a unique pleasure from her new rubber friend.
Mabel thrust her hips forward, pushing herself as deeply into her brother as
she could. He let out a gasp, his eyes going wide as she struck something
inside him and the length of her ground along it.
She pulled back, the worry that she'd hurt him clearing her head. But the
glazed look in his eyes and long, high, ragged delighted breath that Dipper let
out made it obvious he was far from in pain.
So naturally she did it again.
Slowly at first, she worked herself into a rhythm, each time pulling as far
back as she could without pulling out and then plunged back into him,
experiencing all the pleasure of diving headlong into his warmth over and over.
Dipper barely had time to take a breath before she'd hot that magical spot
again and he would let out another moan.
Still she pushed herself harder. Dipper's knuckles were white where he held
onto the edge of the box, and her legs burned with the effort of it all. Sweat
bloomed on her skin and the air in the room felt thicker with every breath.
They came together, Dipper's whole body clamping down on her as his muscles
contracted and he shot a stream of something pale but clear across his bare
chest.
At the same time her nerves exploded inside her. Shockwaves of pure ecstasy
starting in that tight, slick, warmth that she'd found inside him and burning
through her. It raced along every inch of skin, muscles clamping down on
themselves, losing pent up energy, or just collapsing all together
overstimulated as they were.
It was probably the thunderclap that rattled the windows and woke up a sleeping
Waddles on the other side of the shack.
Probably.
***** Aftermath *****
Chapter Summary
     Did she really just do that?
     Yes, now she has to deal with the consequences.
Collapsed on top of Dipper, sweat and other fluids soaking her sweater, the
rising and falling of his chest calming her; Mabel started to come back to
herself.
She wasn't the person that had done...
God what did you even call what she had done to him?
She was sweaty, and sticky, and just plain exhausted. But she was Mabel again.
She rolled off him and onto her back, the wooden planks of the attic floor
rough on her naked skin.
Something was thumping its way up into the attic and Dipper was still moaning
beside her, but she was so tired and her eyelids started to droop.
A hot, wet pig tongue slapped into the side of her face and with a big slupp
licked her.
"GAHH!" Mabel bolted up into a seated position. "Waddles!"
The pig gave her a worried look from where he sad next to her and she couldn't
help but feel a little better as she gave him a big hug.
The quiet, sane moment was interrupted by Dipper moaning in pleasure. A noise
that, now she wasn't hornier that your average highschool football team, was
firmly in the category of things you don't want to hear your sibling make.
She spun to look at him and kept right on spinning as she got an eye full of
his very prominent enjoyment of whatever was still happening to him.
"Eeewww" Mabel shuddered. Well, that was going to keep her up at night.
She stared down at the torn up ruins of her sweater, any of her cloth that had
hung lower than her stomach had been cut away by the straps, and realized
something. It was gone!
She glanced around worried. How alive was that thing? Could it have just fallen
off? Could it crawl away?
She took a deep breath trying not to freak out. First things first, find that
stupid fake dick and lock back in its box.
Shielding her eyes from Dipper with one hand, Mabel worked her way around the
room. Checking behind boxes, pulling sheets off old exhibits, and getting down
on her knees to look under broken furniture; all of which was significantly
less fun half naked and searching for an possessed sex toy.
She was not that lucky.
Extremely reluctantly she turned back to the last place she'd seen the damn
thing, a still quite happy Dipper.
What came next required two beach towels, a pair of rubber gloves, the BBQ
tongs, and four Waddles hugs.
Eventually it was done. The box buried back in the attic, as much piled on top
of it as she could lift. Its dozens of other things, names unknown to her,
safely locked away. The scraps of her clothing were collected and thrown away,
cut up for an art project if Grunkle Stan asked, and everything else used in
the cleanup buried in the backyard.
They had both needed long long showers; but eventually, still not able to meet
each other's eyes, they went to bed.
***** Epilogue *****
Chapter Summary
     Some things you can't ignore...
"Going to bed" was about as generously as you could call Mabel's attempt to
fall asleep. She could hear Dipper twisted and turning, constantly adjusting
his sheets. While she couldn't seem to stop herself from reaching beneath her
pajamas to finger the bruises the straps had left in her skin.
Touching them made her want to do thing, like that thing had left a spark in
her ready to flare up if paid any attention. It was humiliating. She didn't
want to be here, she didn't want the reminder of what had just happened, she
didn't want to think about how good it had all felt... But she couldn't just
leave, Dipper had to feel bad enough without her ditching him too.
She rolled over, keeping her hands on top the covers and trying to get the
images of whips, gags, strange locking tubes, a dozen other multi colored
devices, out of her head.
"Fuck." A exasperated voice spat from the other side of the room.
Dipper's sheets rustled again and in the dark she could just make out him
sitting up to look at her.
"I can't get the blue one out of my head!"
Mabel felt her heart speed up at his words.
Grunkle Stan wasn’t going to be home until Monday.
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