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Spectrum	By : PineWreths Category: +G through L > Gravity Falls Views: 10257 -:- 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
- 3
Wednesday
Dipper awoke gently to his sister’s giggle across the room, and birdsong. She said something indistinct, giggling as Dipper groaned and rolled over, before the twittering of the birds seemingly replied to her.
He was closing his eyes as the little suspicious and paranoid part of his hindbrain finally kicked him awake, dragging his senses to the forefront and mushing them against the large part of him that wanted to just fall back into sleep:
That’s rather a LOT of birdsong. It sounded like half the forest was in the room, and Dip, grumbling, rolled back over to face her and craned open an eye.
He gaped; While half the forest might be an exaggeration, his sister was sitting in the middle of her bed, grinning as the morning sun lit up her yellow banana-patterned sweater, and surrounding her was probably the entire small-bird-and-rodent population of a dozen acres around the Shack.
He let out a nervous “Mabel, wha-” when the animals noticed him, scattering in squawks and squeaks, several sets of claws and feathers and fluffy tails whacking Dipper as they retreated over him in a panic, most of them eventually leaving via the attic window.
His hair a mess and now completely bewildered, he sat up, swinging his feet to the side of the bed and looking at his sister. She had one hand on the head of a very satisfied looking beaver, and the other was at her mouth in horror. Mabel got up, crossing the distance to him, and cradling his head as she checked him for scratches.
“Oh, Dipper, I’m sorry, I’m sorry, I didn’t mean-I didn’t want to do that, it just-well, they all kinda started coming in the window, and it made me feel like a Disney princess or something, and…and…and, well, I guess you saw what happened.”
Dipper looked up at her, grinning, and then laughing. He put a hand on her shoulder, giving it a squeeze as she gave him a guilty, happy smile. “Mabes, while we’re definitely not in a Disney film, that was some pretty awesome sleeping-beauty type of stuff you had going there.”
He stopped, noticing a sleepy yellow-chested meadowlark poke itself from her brown curls, giving her brother an angry trilling tweet, before hopping onto her shoulder. Mabel giggled, running a finger along its neck and getting a fluffed happy poof of the chest feathers and a frantic wiggle of its head as the little bird appreciated the itches.
Meanwhile, Dipper chuckled and fell partially back as the beaver butted his hand a bit. It was somewhat surreal, as Dipper had never gotten to actually pet a beaver before; They’d attacked him and he’d defended himself on a few occasions, but this was his first encounter with a friendly one.
Finally, Dipper stood up, still holding his sister’s hand before trailing it and releasing it. In a tender, playful voice he said “All right Princess Mabelton, time for us to go help with the shop. It’s ten minutes to opening, and Grunkle Stan will be peeved if we’re late.”
She nodded, and after Dipper threw on a change of clothes, protested against Mabel’s stern finger, took a much-needed shower, donned a fresh set of clothes, and joined her downstairs, Grunkle Stan was waiting, foot tapping impatiently.
“All right kiddos, time for us to milk some suck-Whoa, Mabel, that thing real?”
He was looking at Mabel’s new pet beaver, a look of avarice gleaming in his eyes, but Mabel seemed to not notice, giving her Grunkle a happy “Yup!”
He chuckled, rubbing his stubble for a second in thought before saying “Alright. Dipper? Open shop, run the first tour. Mabel? Come with me.” He led Mabel towards the kitchen, her beaver following and the meadowlark singing merrily as Dipper went to meet the first tour at the front door.

Leading the group of gawping tourists through the final corner of the shop, Dipper was in the middle of saying “And now, here, we have the tentacle of a genuine, honest-to-goodness Sharktop-” when Grunkle Stan’s booming voice drowned him out.
“Come one, come all; See the amazing Squirrel-Girl!”
Dipper’s jaw dropped, this time in disbelief. Mabel was dressed in some old green leotard and brown leggings, from an old Robin Hood costume they’d worn for Summerween a few years back, and she had an enormous, hideously-fake tail that Dipper vaguely recognized as the faux-fur carpet rolled up in the corner of the attic closet.
Next to her was her beaver, which looked to be spray-painted and coated with reddish-copper glitter, and a few tufts of what looked to be wig-hair glued to the flat tail.
He looked at his sister; She was smiling, but it had the same manic edge Dip recognized as having been on his own face when he got to play a preteen wolf boy. One child got too close to the irritable beaver, and it nearly took off a finger, Mabel holding it back as Grunkle Stan laughed and waved a reprimanding finger that was almost removed as well.
“Ha, well, good thing we’re not wood, eh kid?” he said, ruffling the hair of the now doubtlessly-traumatized toddler before turning back and spouting off some nonsense “facts” about the “Squirrel-Girl.”
Dipper managed to avoid catching Grunkle Stan’s gaze as he took over the tour and led them towards the gift shop, and as soon as he was out of earshot, Mabel hissed to her brother “Dip, help! I wanted to help Grunkle Stan, but I think this was a really bad idea.”
He nodded, but it wasn’t for another three tour groups before he was able to come up with a suitable plan. As Mabel held her rictus grin for the last set of photos, he had managed to collect her clothes, and call Soos as a distraction.
Soos’ arrival couldn’t have been more timely, and as he began parading in front of the shocked tourists in his ridiculously tiny question-mark mascot costume to the sounds of gasps of horror and alarm, Mabel changed and followed Dipper out the back. She pulled and brushed as much of the glitter and wig-hair off of the beaver, which she had nicknamed Flapjack, before the twins peeled off.
Dipper saluted Soos, who caught his eye and returned the salute, seconds before Grunkle Stan tackled the man-child and dragged him off to hide him in the Shack. He had left the details of the distraction up to Soos, but after this Dipper knew he’d owe him big-time.

And then the twins were away, safe for the rest of the day. They spent it downtown, Mabel leading them to the pet shop where she cuddled the various ferrets, bunnies, kittens, and puppies until the employees had to ask them to buy something or leave. From there, they grabbed a loaf of bread from the grocery store, and headed down to the pond to feed the ducks until the afternoon light started to fade into night.
As they sat on the park bench, Mabel was now surrounded by hungry and hopeful geese, and fulfilling her false identity with an equal number of begging squirrels. Dipper had run off earlier to get them dinner, and had returned with a pair of boxes of Chinese takeout.
Mabel opened up her very-specifically vegetarian fried rice and dug in; Dipper had commented on her choice of something other than her normal favorite of peking duck, but she shot a significant wordless glance at her surrounded animal audience and he didn’t push it.
Still, Dipper had grabbed his traditional black pepper chicken, but after a few bites, the mournful looks from the assembled avians finally had him picking at the fried rice and chow mein instead, and with a bit of both regret and resentment, he left almost all of his main course untouched.
They slowly made their way back home after eating, most of the animal following dispersing as they left the park. Upon getting within sight of the Shack, Mabel shooed Flapjack off into the woods. He gave her a hurt look, before chittering and disappearing behind a stump as she scolded him, saying “Hush that! I’ll be back tomorrow, okay?”
Grunkle Stan was disappointed when Mabel returned without the beaver, but apparently the stack of bills next to him was enough to offset the inability to milk the attraction a second day. Mabel had shrugged at Flapjack’s absence with a guileless “Eh, Nature; Whatcha gonna do, huh?”
That night, as Dipper curled up in bed with stomach protesting at being denied a meal of filling chicken, he could hear Mabel giggle again. He looked up to see her, illuminated in the light of the moon in the bedroom window, as she sent her little meadowlark, which despite Dipper’s protestations of “ruining the name,” she had named Optimus.
She turned, still standing, with the blue moonlight mingling with the yellow stars of her nightie, and gently tucking a foot behind her, said with a bit of shyness “Dip, despite all my-my weirdness, you still…love me?”
He grinned, a bit sad that she was apparently going through such self-doubt as to keep asking him, but he smiled and nodded. “Of course, Princess Mabelton,” he said with a wink. She giggled, and smiled back, before sitting in her bed and drawing up the covers. She looked at him with sleepy eyes, as he closed his own.
“Good night, brobro.”
“G’night, sis.”

Thursday
Dipper awoke to the sound of sizzling, and a smell that made his stomach growl with excitement. Leaning forward, he was just in time to see Mabel bump open the bedroom door, carrying a plate with a platter of bacon rashers, a small mountain of slightly-burnt buttered toast, and what appeared to be the majority of a dozen eggs.
She set down the tray on the bed with a clatter, sitting and crossing her legs opposite of him. She grinned, and thrust a fork out at him. “A little birdie told me you went to bed hungry last night.”
Dipper raised his eyebrow, as she stared meaningfully at his stomach. “Dip, your stomach sounded like two tomcats fighting at the bottom of a well.”
He chuckled, but then looked around, cocking his head. “Hey, what happened to Optimus? Is, uh, is Flapjack back yet?”
Mabel stared blankly back at him for a moment, before realization clicked. “Oh. OH! No, they-they haven’t shown back up yet,” she said, but she grinned at him again in reassurance. “I’m sure they’ll be around the Shack here in a few days.”
He nodded, smiling back; Internally, he was worried she’d have been heartbroken, like the other times her wild “pets” she’d brought home had escaped, never to return, and it looked like the bird and beaver were much the same. Still, it was good that Mabel was coping well, and Dipper figured she must have finally gotten used to critters running off by now.
A light rain had started, despite the sun shining through the cloud cover, and Grunkle Stan had grudgingly admitted defeat at the lack of any crowds before noon. He finally closed the Shack right after a brief lunch, and turned the twins loose for the day.
Mabel immediately dragged Dipper to the mall; Evidently she hadn’t gotten her fill of goodies that Sunday, and dragged Dip through Purls Before Swine, and then into Glitter Emporium. Dipper avoided touching any surfaces inside, an ultimately futile effort, and was led by Mabel through each remaining supply store in the mall, as she gradually accumulated a collection of feathers, fabric, thread, plaster of paris, and other bits and ends.
That night, Mabel hurried and ate quickly, and then retreated to the attic. Dipper had come to the door, hearing the sounds of intensive crafting behind the door, but when he had knocked, the sounds went silent. A moment later, Mabel was at the door, holding it just wide enough that he could see her head, but nothing beyond.
Attempting futilely to look past her, Dipper said in an annoyed tone “Mabes, what’s going on?”
She grinned, a bit of plaster dust and glitter falling from her hair as she said “It’s a surprise!” There was a little titter of birdsong, and Optimus appeared from her hair, covered similarly in a fine powder of dust and glitter.
Dipper chuckled as he saw Optimus fuss and preen on top of his sister’s dusty hair, and said “Well, alright then. Glad to see you at least got Optimus back.”
She grinned after a blank second, nodding enthusiastically before shutting the door with a “Kgottagobyebrobro!” Dipper shrugged, nonplussed, with hands in his pockets as he strode down the hall and stairs, to watch some cable with Grunkle Stan.

They had just finished watching the leadup to one of the season finales for Game of Thrones, Dipper having seen the series before and shifting uncomfortably with hidden guilt every time the Lannisters came on as he worried that Grunkle Stan would spontaneously develop the ability to read minds. Still, it was with relief when he got up after hearing his sister calling for him from the top of the stairs.
He was at the base of the stairs when Grunkle Stan called to him. “Dipper,” he said with a frown, “Your sister’s been doting on you an awful lot these last couple days.”
Dipper could feel his gut plummet in fear. He knows, he must know. Oh shit oh shit-
“Seriously, I saw the bag she brought home earlier, and I know I certainly don’t pay you guys enough for that. Where’s she getting the money to buy out a small craft store?”
Dipper stopped, the gut plummet rebounding in confusion as he stammered, and then stopped. He gave his Grunkle a helpless shrug, saying half-jokingly “I dunno; Maybe she steals it?”
There was a long pause, and then Grunkle Stan burst out laughing, slapping his knee before wagging a finger at Dipper. “Well, you tell her that her old man is proud of her in that case, and to remember to keep thefts under two grand unless she has an airtight getaway plan, capish?”
Dipper, unsure what to say, simply nodded, and ascended the stairs towards his sister’s calling voice. He stopped at the door, seeing an intense white light coming out from under the door, and carefully took the knob to open it.

His footfall staggered, the door shutting behind him as he raised up his hands to shield his eyes. The room was suffused with glittering light, but as his pupils shrank and he adjusted, he could see that instead the room was filled with strings of white and blue and green christmas lights, and dozens of vanilla and sandalwood-scented candles that covered almost all the available vertical spaces.
The twins’ beds had been shifted at a slight angle to make room for the centerpiece; An enormous, white, shimmering orb, with waves of blue and green crepe paper and fabric surrounding it.
As he looked, he could make out that it wasn’t an orb, but rather a white pair of large clam shells, nearly five feet high, made from plaster and bedecked with so much glitter that they were practically luminous themselves. He saw a shuffle of movement rock the shell halves, and he could make out a brief eyeball peeking at him from between a gap in the halves, before there was a shudder of movement.
The shell halves began to open, slowly, and he could see revealed in them and illuminated directly by a pair of lights that snapped to life inside the shell, was Mabel. She looked like a goddess, and she shot him a coquettish smile over the edge of a piece of white sheer fabric she held like a cape. Green glitter makeup and eyeshadow adorned her, making her brown eyes pop, and as she slowly turned as the shells shuddered to a stop, fully open, he could see that she had made some shimmering green material into a simple, strappy and revealing bikini that resembled seaweed.
He chuckled, and let out a low appreciative wolf whistle, causing her to grin and take a few strides towards him. She left the fabric cape behind her, clad now only in the form-fitting, undoubtedly custom and incredibly insufficient excuse for a swimsuit.
Dipper had taken a seat in an available armless chair that had evidently been left for him, draped in more of the same shimmering material, but his attention was focused on his dream of a sister as she floated over to him.
In a little voice, tinged with a hint of worry, she said “Uh, so, d’you like it? Like, all of this” She gestured around, ad he could tell she was including her outfit in the sweep of her hand.
He grinned, and gently grabbed her wrist to pull her to straddle his lap, “Mabes, I don’t like it-” Her expression fell as he continued with a rogueish grin. “I love it.”
She looked at him, narrowing her eyes in a moment of annoyance at his phrasing before throwing her head back and giggling. Dipper took the opportunity to lean forward and nibble the nape of her neck, causing her to flail and giggle, but then cross her arms behind his neck and grind her hips against his erection.
Dipper let out a happy groan, and kissed his sister, her breath catching as he ran a hand across the silky tiny swatch of material to tease the nipple hidden beneath. She ran her tongue across his lips, her hands running inside the back of his pants to cup at his ass, giving him a playful squeeze before they were removed and went to unbutton his pants.
Dipper shimmied his hips up, helping Mabel as she dismounted temporarily to remove his pants. Dipper had started to sit back down, but stopped for a moment as she grabbed his t-shirt and yanked it off to toss by the bedroom door. As she did, she murmured huskily to him “Oh nooo, I can’t have my Adonis encumbered by these dirty clothes.”
FInally, it hit Dipper with what his twin was shooting for, and kicking himself internally for taking so long to recognize it, he giggled back before dropping into an equally low, sensual tone as he said “Well, I do as my Aphrodite commands.”
Mabel let out a squeal of delight, and was about to smother him with another kiss, when she stopped, glancing towards the door. In a worried tone, she said “Dip, is Grunkle Stan busy?”
Dipper frowned, and trying to ignore his nakedness and awkwardly-swinging erection, listened at the door. He heard nothing at first and then a “Rob, don’t-no…nonono-Noooooo!” from downstairs.
Dipper turned back to his sister, grinning as he said “He’s busy for the time being.”
She giggled and practically ran over to him, grabbing him by the cock to lead him as he protested halfheartedly. She brought him back to a corner of the room, surrounded by candles and electric lights, a pile of pillows covered with the same silky materials she’d surrounded the clamshell with.
She spun past him, to land and writhe in the fabric, before turning to him and grinning. Mabel dipped a finger down, teasing past her chest and belly before dipping below the fabric straps, the outline of the material clearly revealing as she dipped a pair of fingers into herself, bringing them out and winking at Dipper as she ran a tongue along one of them.
Dipper let out an animalistic growl, grinning and crouching over her. He pulled the material aside to suck on one of her nipples, as his other hand followed hers to rub against her clit. She moved her fingers away, letting him take charge there as she began to stroke and pump his cock. Dip groaned, and half-kissed, half-bit the nape of her neck, causing her to squeal with pleasure and thrust back against his hand.
He pulled the material of the makeshift bikini aside, and ran his cock up and down her clit, teasing it with little strokes as she shuddered and whined insistently. As she looked at him, biting her lip and begging with her eyes and her hands on his hips, he obliged her, leaning forward to thrust into her and fill her. Mabel’s legs shot out to curl around him, pulling her closer to him as he thrust again.
She gasped, running a hand down to her clit to toy with it as her other reached up to run along his chest, and then rake and brace his shoulder. He leaned forward, biting her shoulder gently before turning it into a trail of kisses down between her breasts, before rising again to lock into a kiss with her.
Her thrusting was insistent, her hips rising to match his thrusts, and Dipper could feel a tingling building. He groaned, feeling himself clench already and cursing himself for not figuring out what she generally had planned for the night. Normally he jerked off to take the edge off and give himself a bit of stamina, but now he was at 100% and could feel himself spasm.
Mabel shuddered as well, drawing him tight with her legs and arms around his back, letting out a muted groan that pitched into a squeak of pleasure as she came. That sent Dipper over the edge, and he shuddered and filled her as well, causing her to spasm again and groan appreciatively as she pulled herself tight against him again.
Then, sighing happily, DIpper flopped to rest beside her, panting in time with his sister as tey both basked in the afterglow,. His hand was laced tight with hers, and he lifted it to give her a little kiss, and they sat and enjoyed the mutual warmth in the overwhelming light of the room.
After a while, Dipper could feel sleep[ pushing at his senses; He chuckled as he saw the clock indicating it was shortly after midnight, and he with Mabel, still in her seaweed bikini, they went around and carefully blew out the various candles.
Then, Dipper helped her carefully scoot the beds back into place without clattering them against the floor. He was impressed she’d done this by herself, but then again, with all the battle scenes and shouting, both on the show and from Grunkle Ford, he probably wouldn’t have heard a bomb going off in the attic either.
FInally, everything was roughly put away, at least enough that if Grunkle Stan poked his head in, he wouldn’t see anything amiss. The twins had gone to bed, Dipper appreciating the view as Mabel switched out of the bikini, temporarily revealing the pale butt and her twin giving it an appreciative squeeze. She had squealed, giggling and with her brother smothering the squeal with a couple kisses, but then she’d pulled on a green forest-scene shirt and fallen asleep seconds later.
Dip gave her a kiss on the forehead, before retiring to his own bed and falling asleep. His eyes were feeling strained from having what felt like the light of the sun stabbing them for a few hours, but apart from that, the evening had been exceedingly enjoyable.
He was awoken briefly from sleep a few minutes later, hearing Mabel shifting in her sleep and an unlit candle clattering to roll on the floor. He leaned up, unable to see much with the sleep in his eyes and the darkness, and Mabel spoke.
“S-sorry, Brobro. My bad, I derped and kicked a-a candle.”
He smiled, seeing her give him a little smile in return with her teeth in contrast to the darkness, and said “Good night, Mabes,” before rolling back over and falling asleep.
“Good night, Dip.”

Hours later, Mabel crouched down and carefully opened the fridge, grumbling when the light illuminated a container of orange juice. She gave it a quick sip, pumping a fist in triumph as moving it revealed a lone rasher of bacon on a plate. She scarfed the rasher, doing a little dance in her yellow nightie, and the stopping when she got an annoyed peck on the ear.
“Ow, fine, fine, we’ll get what we came for you little tyrant.” She closed the fridge, creaking open a cupboard, and pushing past the chips and crackers before finding Grunkle Stan’s old bag of sunflower seeds. She grabbed a double handful, emptied them into a cup, and then thinking about it, stopped and just emptied the sunflower seeds into the cup. She held one up to the bird on her shoulder, who greedily cracked open the nut and scarfed the contents before giving her a little happy twittering peep.
“Shhh, Opti! Don’t wanna wake up the whole house!” With that, Mabel snuck off back into the dark Shack with her cup, the shimmers of the dawn barely visible in the clouds outside.
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Spectrum