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Spectrum	By : PineWreths Category: +G through L > Gravity Falls Views: 10256 -:- Recommendations : 0 -:- Currently Reading : 0
Disclaimer: I do not own Gravity Falls, nor the characters from it. I do not make any money from the writing of this story.

Chapter List
- 1-Spectrum
- 2-Part 2
- 3-Part 3
- 4-Part 4
- 1
- 2
Sunday
It had been a really weird week for Dipper.
Sunday had started off normal, Mabel seemingly distracted with another of her craft projects or something. She’d dragged him to the store and around town in the Shack’s golf cart, popped into a couple stores to get groceries Grunkle Stan had given them a list for, before ending with a brown paper bag full of something from the office supply store Papyrus Dreams.
Her unwillingness to show him the contents of said bag hadn’t alerted him to anything; It was weird, but Mabel loved her surprises, and in any case it was half the size of the tub of yarn she’d bought just two months back from Purls Before Twine, the knitting and sewing store in the mall. When they got back to the Shack, she gave Dipper a quick kiss when Stan wasn’t looking, and shoved the bag into the closet on her side of the attic room.
Eh, no biggie. She’ll be done with whatever it is she’s crafting in a day or two, and maybe even let the cat out of the bag earlier. To be honest, Dipper’s curiosity had waned after the first three times this summer she had been secretive like this: When she had gotten supplies to try and make him a cake that looked like the hive of dungbees he’d stepped in, which had resulted in painful swelling and countless hot showers; Then a few weeks later when he’d poked around and discovered that she intended to dress them up as Oreo cookies, with her as the frosting and him as the cookies; And then just a month ago for their sixteenth birthday, when he’d found the blue journal she’d made for him, with a gold dipper constellation across the front as he’d almost filled up the gold tree-emblazoned one she’d made for him the year before.
Dipper grinned at the memories as he fell asleep; The Summerween costume was great in retrospect, as it gave him an excuse to mush up against her backside in a big cookie-handed hug to form the sandwich. For their birthday, Mabel had given him a very special and very personal gift for his birthday that night, as did he, and they spent the evening thoroughly enjoying each-other’s “pleasurable company.”
Still, Dipper had seen the look of disappointment flash across his sister’s face, the hurt as she saw that, for a split second as he opened up the wrapping paper on the journal, that he knew about it. That had been like a punch to the gut, and he’d struggled to flash a smile up for Soos, Stan, Wendy, and the others, while privately resolving to let his sister’s secrets lie undisturbed from that point onwards.
Besides, he thought as he succumbed to slumber, It’s not like Mabel would be hiding something huge from me.

A few hours after he fell unconscious, Mabel crawled out of bed, grabbed her bag, and took it with her to another, specific room of the Shack. Lights flashed repeatedly in the windows, and quiet, triumphant laughter echoed briefly throughout the room before the lights went dark.
The lights of the dawn were barely tinting the skies above when Mabel returned to the bed opposite her brother, giddy with excitement and nervousness about the upcoming day.

Monday
“Morning, brobro!”
Dipper screamed in response to his sister screaming in his face, flailing and knocking her aside before landing on the floor, his blankets pooling around him.
Mabel had fallen backwards, a hurt and concerned expression across her face. She had already donned a red sweater with a bright-orange cherry across the front, and the little green bells that served as cherry leaves tinkled merrily as she rubbed her bruised cheek.
Instantly, Dipper was full of apologies, coming over to cradle her and give her a little kiss on the injury as he murmured more apologies. He felt her stiffen at his touch at first, but the kiss seemed to make everything better as she turned and bounded to her feet, dragging Dipper along by the hand.
“No time to waste, brobro, we’ve got a long day ahead of us and tons of ‘splorin to do!”
Chuckling, Dipper got dressed, wolfed down a plate of Stancakes for breakfast as his twin practically inhaled hers, and barely half an hour after Mabel’s voice dragged him kicking and screaming from REM sleep, Dipper was chasing her through the woods.
The day passed in a blur, as caves were explored, waterfalls slid down, trees climbed, and trails followed. Dipper was panting before they stopped for the brief picnic lunch in a quiet, yellow-grassed glade, and by the time they had veered back to the Shack he was thoroughly spent. Mabel gave him a quick kiss, out of sight of the Shack’s windows and patrons, and alughed as she ran ahead.
He groaned, with tiredness and mild blue-balled disappointment. Mabes had been teasing him all day, stopping from running ahead to give him little kisses and caresses, but then running off before he could do much in return.
Now, after a day of running through the forest, Dipper’s mind was entirely focused on sleep and rest and the wonderfulness of a soft pillow against his head. Indeed, after a brief dinner, he went and prepared himself for the night, and did exactly that.
Before he sat down in his own bed, he noticed Mabel sitting in her strawberry-seed-pattern sleep shirt. She was staring at him, looking somewhat sad, so body still aching, he came over and sat near her feet on the bed, asking “What’s up, sis?”
She looked up at him and then looked away, blushing as she said in a little voice “Dip, do…do you really love me?”
Dipper stared, slack-jawed at his sister, before abruptly leaning forward and pulling her into a hug. He could feel her stiffen, and then melt against him, letting out a little sniffling sob before squeezing him tight.
He murmured into her shoulder “Of course I love you, sis. I…I’m sorry I’m not really feeling ‘in the mood’ tonight, though,” he said, leaning back with a rueful grin.
When she leaned back, her sad expression was now one of glee, but she chuckled at his comment, nodding and rubbing her neck. “Well, I kinda did run you ragged today,” she said, with a bit of a huff of disappointment.
He punched her arm lightly, saying “Hey now, why the sad face? I’m not going anywhere, so we can have all kinds of ‘fun’ tomorrow, okay?”
She looked incredibly disappointed, but then gave him a little mischievous grin and said “Yeah, right, I guess so.” Then she leaned in, giving him a kiss as she said “Thanks, brobro,” before leaning back on her pillow with a smile.
Dipper returned the grin, going back to his own bed, and falling asleep shortly after his head touched the pillow. As he drifted off, he could hear his sister shuffling around, likely trying to get comfortable in the humid summer heat, and he smiled as he fell asleep.

Tuesday
Dipper awoke to Mabel gently calling his name. “Dipper? Diiippeeer?”
He groaned, rolling over and rubbing his eyes. The light filtering through the window was far stronger than he expected, and a bleary look at the clock by his bed revealed…11:17 in the morning?
He bolted upright, only to be stopped by Mabel’s palm against his chest. “It’s all right, brobro,” she purred, giving him a smile. “I told Grunkle Stan about how sick you got from that gnome bite in the woods yesterday, and he agreed with your request for the afternoon off from working in the shack so I can take care of you.”
Dipper’s brow wrinkled in confusion, but then his eyes widened as Mabel leaned forward, engulfing his mouth. His cock immediately went from a morning half-chub to a solid steel beam in a span of a half-dozen heartbeats, and he could feel himself go light-headed with the ferocity of her mouth against his.
Still, not all coherent thought-making ability had escaped him, and he broke the kiss to gasp “The door?”
His sister sat back, shaking her head in amusement at her brother’s paranoia, and she stood and strode over to the door, twisting the lock to show him it was securely fastened. Her act of getting up suddenly made it abundantly clear to Dipper and his libido that while she was wearing an orange sweater with the glittery words “Orange you glad to meet me?” across the back, she had neglected to wear apparently anything else, the smooth orbs of her ass flashing above her pink legs.
She turned back to Dipper, granting him a heavenly view of her little landing strip above soft lips, and when she came back to bed and sat heavily on his lap. Dipper’s shaft was now diamond-hard, and Mabel gave him an appreciative wiggle her wetness seeping through the thin sheet between them as she smiled at her brother.
Dipper gave her a growl, and went to yank the sheet aside; Thus freed, Mabel giggled and then moaned with lust as she rubbed herself along the top of his shaft. An experimental hand under her sweater revealed she was wearing no bra, and her nipples were as excited as the rest of her. Dipper gave one of the breasts a squeeze, and she let out an appreciative groan as she slid back to sit heavily on his cock, engulfing him inside of her.
Dipper’s hand froze as all brainpower went towards appreciating this feeling, and he grinned and thrust upwards with his hips. Mabel bit her lip, leaning back above him as one of her hands braced herself on the bed and the other reached under her sweater.
Dipper’s eyes rolled back in his head, the pleasure getting to be almost too intense, and he fell backwards against the bed, feeling his cock start to pulse. Mabel noticed, letting out a husky “Ooh,” but she got up and off of him, eliciting a groan from her brother.
That groan of disappointment turned almost immediately to pleasure as she engulfed him with her mouth, sucking and running a hand to trace down his lightly-hairy chest and towards his cock. He groaned again, stiffening and abruptly leaning upwards as he came, panting, and feeling Mabel start to jerk back in response..
After a few blissful seconds the afterglow faded, and Dipper could feel that Mabel had gone still. He looked down and her eyes were wide, her face adorable with puffed-out cheeks still holding the delivery of cum he’d given her, but the look of worry something he’d never seen before on his twin after a blowjob.
“Are…is everything all right, Mabes?” he said tentatively, and Mabel seemed to snap out of it, turning to look at him, her wide eyes suddenly crinkling at the corners with excitement. She swallowed, and then in an enthusiastic voice said “Oh, everything’s amazing, Dip. Ohhh man oh man oh man, I’m so excited!”
He cocked an eyebrow quizzically, but she just grinned and looked meaningfully towards his deflated member. “Whoo man, Mabes, that was intense. God, I love you,” he said as he flopped back on the bed, and he noticed her stiffen a bit next to him.
“Like, really really love me?” she said, a bit apprehensive, and he chuckled.
“Of course really-really, sis. I meant it when I said it last summer, I meant it when I said it last night, I mean it when I say it now.” He adopted a solemn air. “Dipper Pines is a Man of his Word.”
Mabel broke into happy giggles at that, but then straightened to match Dipper’s noble bearing. “Yes, yes, well, Dipper Pines also Owes His Sister a sum of Twenty Dollars for a Bet Involving A Pig Last Month.”
Dipper chuckled, averting his eyes and saying nervously “Eh, hehehe, uh, I have no idea what you’re talking about and wasn’t serious about that bet anyways.” He rubbed a hand against his neck, but then froze and stared as Mabel ran her hand down to cradle his flaccid dick, and he could feel it stir in her hands as she gave it a few gentle strokes.
“Man, Mabes, again? Already? I mean, I’m not complaining or anything, but…”
She grinned, and leaned down to give it a brief kiss on the tip, causing it to surge against slightly in response. “Brobro, you’ve got a full day off of work, and I intend to help you make full use of it.”
Dipper leaned back, in heaven as she bobbed her head and began to suck him to his full firmness again.
By the time dinner rolled around and Dipper finally got up for his first shower of the day, he had lost count of the number of times he’d came, most of them inside his sister in some fashion or another. He was as sore as yesterday, and felt like he’d been attacked by an enormous mosquito that only sucked blood from scrotums, but overall it was a good soreness.
Grunkle Stan had commented on his nephew’s disheveled appearance at dinner. “Man, you look like you barely got any sleep, Dipper. Sure you’re going to be up for work tomorrow?”
Dipper smiled, glancing at Mabel across the table who chuckled at him in return. “I think I’ll be all right, Grunkle Stan.” Stan rolled his eyes, but went back to the plate of chinese takeout.
That night, after they had made their way upstairs and brushed their teeth, his twin had slid down his pajama pants and began grinding her sticky pussy lips against his somewhat slow-to-respond cock. Still, the body and flesh were both thoroughly willing, and Mabel had made her way back over to her bed after fucking him to completion two more times.
Dipper and his now thoroughly-sore hips began to fall asleep. Behind his back, he heard Mabel thrashing a bit in her sleep, and even a giggle as apparently something funny must have occurred during some dream or another.
Dipper smiled to himself, and slept dreamlessly that night.
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Spectrum