"Why are we doing this again?"

"Because I said so, alright Ford?"

"Grunkle Stan? No offense, but this is a horrible idea."

"I didn't ask you, Dipper. Now hows about you and your sister get a chainsaw for your grunkle?"

"Grunkle Stan, can I use the chainsaw?"

"Sure, kid. Just don't kill yourself with it."

"No kids. No touching the chainsaw. I'll get it." Stanford stepped away from where the rest of them were working on the porch. "I'm going to have to agree with Dipper on this one, Lee. This is a horrible idea."

Stanley ignored his comment, continuing to superglue two pieces of wood together, getting his hands stuck to them in the process. "Looks like you kids are going to have to saw my hands off," Stanley joked.

"NO!" They all yelled in unison, continuing to build the contraption (completely Mabel's idea) that they planned to use to launch an oblivious Waddles into the sky with. Of course the plan had been molded slightly (because of Ford and Dipper's fears that the pig would make like a bug and splat against a car's windshield. Specifically Stan's car, which was parked only a few meters away from the launch site.

Waddles waddled onto the porch after Ford left, struggling to move gracefully with the jet pack strapped to his (Her? Their? It's?) back.

Ford Came back with chainsaw in hand and multiple pairs of goggles, handing them out before turning the saw on and cutting through different pieces of wood. Each of them quickly set to work gluing wood together and setting it up into the shape of a slingshot, complete with large rubber strings and a leather pouch for the pig to rest in before his ascent (cut out from the back of the couch, but Grunkle Stan didn't need to know that).

When they were done they took a moment to admire their work before Stan cut in with a "Well are we gonna launch this pig into the sky or what?" To which everyone but Ford cheered in assent to with a "Waddles! Waddles! Waddles!" Ford face-palmed at the obvious lack of concern for the pig at the moment and chose to make sure nobody got hurt by hovering close-by in the case of an accident.

Stan loaded the pig into the slingshot and pulled it back far enough so that the smaller twins could get a hold of the pouch. They all pulled back and then let go, letting Ford press a remote button that caused the jet pack to start speeding the pig straight into the forest where the twins ran after him. Laughing and shoving each other, they ran after the flying pig, until the jet pack ran out of fuel and sent Waddles flying straight toward an oddly shaped stone sticking out of the ground. Mabel ran faster, managing to scoop Waddles straight out of the air before he could go plummeting into the stone. "Gotcha. You wanna try that again, Waddles?" Mabel asked with an elated smile on her face.

"Um, Mabel? You're going to want to see this," Dipper said, standing over the stone which was half-buried in the ground in the center of a small crater. Mabel stepped over to take a look at what Dipper was talking about to see that the oddly shaped stone Waddles almost crashed into was in fact a statue of Bill Cipher. "Guess this is where he ended up," Mabel said somewhat solemnly.

"Welp. Wanna draw a mustache on his face?" She continued.

"No!" Dipper shouted. "How about we get him out of there? Or maybe we should get our grunkles to take a look at it?"

"Getting him out it is!" Mabel answered, grabbing the statues hand and yanking before falling on her butt as a bright light emanated from the statue. It was if a bomb had gone off and they were caught in the aftershocks, bracing themselves as the ground trembled and the light pulsed, blowing the trees away from the site. Dipper held onto a root deeply embedded in the ground, bracing himself as pulse after pulse of the light pushed him away and Mabel slid away hitting her back against a tree as she held to Waddles for dear life.

Soon enough the pulses faded, leaving the two sprawling and disoriented. The two stood up, dusting themselves off and glancing at each other with uncertainty before stepping toward the crater and peeking over the edge. There, they saw what appeared to be a boy their age with long black hair that faded to blue at the ends that was put up in a ponytail dressed in a pair of black shorts, Keds, and a blue sweater, which was covered in dirt at the moment. The boy had tanned skin and seemed to be fast asleep, curled into a little ball in the bottom of the small crater.

"What the-?" Dipper started before Mabel slid into the crater, already poking and prodding the (probably not dead) sleeping person. "Mabel!" He called after her, sliding down as well. Mabel brushed the boy's hair out of his eyes and the boy started stirring, slowly opening one eye at a time. The sleeping person's sky blue eyes fluttered open before said person was scrambling away from the twins in a frenzy. "Calm down, we're not going to hurt you," Mabel immediately said in a calming manner causing the boy to pause in his movements. "Mabel! We don't even know who this person is," Dipper argued.

"Where the hell am I?" The boy asked in an oddly familiar voice. "And what is this body?" The boy sounded (more than) slightly disgusted as he peered down at his chest, patting himself down and then staring at his own hands in awe.

"This is Gravity Falls. Do you really not remember how you got here?" Mabel asked, ignoring the odd part about the body and leaning in with stars in her eyes. "Do you know what your name is?"

The boy seemed taken aback by her tenacity. "Um, the name's Bill Cipher. Figured you of all people would recognize me," The boy snarked.

"But Grunkle Stan killed you. This isn't possible," Dipper stepped back.

"Sure it is, kid. Unlike you I've got safety nets in the case that I die." Bill stood up further, looking less confused than he had before and more confident in his actions. He snapped his fingers in an attempt to perform his magic, which didn't work. His brows furrowed and he snapped his fingers again. "Come on. Why isn't this working?" He mumbled, aggressively snapping his fingers.

"What?" Dipper looked on in confusion, making no attempt to stop him. Bill ignored him, continuing to no avail to activate his magic. Mabel grabbed his wrist, not so gently, stopping him and looking him in the eye. "Let's get you out of here first. And washed up." She started dragging Bill out of the crater and Dipper's jaw dropped as he watched his sister drag the former demon toward the shack. "Wait, Mabel! He literally just said that he was Bill Cipher!" Dipper called, scrambling after her.
Mabel pulled Dipper closer to her and whispered into his ear. "I think this guy's just a crackpot cultist with a concussion. Probably from that big shock-y thingy we experienced earlier." Bill growled at her. "You know I can hear you."
She smiled brightly. "Which is why we're going to bring you to our grunkles and then possibly to a hospital. And even if you really are Bill, Great Uncle Ford will be able to stop you from doing anything bad before you get the chance," She said in a menacing tone before turning and skipping off cheerily ahead of the two boys. The two glanced at each other and Dipper shrugged, walking ahead of him. "Better keep up. You wouldn't want to piss off my sister. She can be scarier than you when she wants to be."

Bill stared at the two twins before following along (he had nothing better to do, really, and he was just as confused by this series of events as the twins were). He experimentally tugged at the hair that was tied up in the top of his head, causing it to slide to one side of his head sloppily and threads of blue and black hair to slide out of the ponytail. Mabel giggled at his obvious lack of knowledge of the human anatomy. She started walking behind him and pulled his hair down, letting it fall down to his mid-back. "What are you doing?" Bill turned his head slightly toward Mabel.

"I'm going to braid your hair, now keep your head straight," she yanked his head back into place and started tugging at the strands, braiding them with obvious skill. When she was finished, she tied it up with the rubber and that she'd pulled from his hair earlier.

"You know, you have long hair for a guy," Dipper pointed out. Mabel glared at him for that. "Shut up, Dipper. Lots of guys have long hair," She said, poking him in the side. "Yeah. Girly guys," Dipper poked her back.

"Maybe because the body I'm currently in is female right now? You ever think of that?" The two stared at him, one with stars in her eyes and the other with a look of pure horror.

"Why-?"

"You're a girl?!" Mabel squealed in excitement.

"Technically," Bill answered. "I'm still male in the sense that that's what I am (although, that's technically not true either. It's just the closest thing to what I am in human terms, since my home dimension actually has fourteen billion genders and that would be too confusing for your tiny minds and would probably take years of paperwork). I just have the body of a female. I believe some humans might consider that to mean that I am trans-male. Although I personally don't care much about gender. So I guess I could be cis-female or even genderqueer. I don't care either way."

Mabel suddenly hugged Bill tightly. "We're going to be great friends," She whispered in his ear, causing a shiver to run down his spine.

"But why are you a girl?" Dipper seemed on the verge of some sort of teenage meltdown.

"I don't know. Why is your hair brown? Why are humans bi-symmetric? Why are humans fat, wet bags of meat withering under the oppressive tyranny of time and puppeteered by the arbitrary whims of natural selection? Maybe it's because humans are designed by a blind and idiotic uncaring chaos. Or perhaps someone really has it out for me. The world may never know."