Omake - Wendy's prank

"Fights a giant robot, makes you jewelry, and always chooses you over anyone else?" Wendy asked, trying her best to sound impressed. "I would do things to him that are illegal in Georgia."

"He has done a lot for me," Mabel admitted with a thoughtful look in her eye.

— Ten minutes later —

Dipper marched up to Wendy, lipstick marks scattered across his face, rope burns on his wrists. "This is revenge for breaking you and Robbie up, isn't it?"

"Little bit," Wendy admitted.

"Ohh, Dipper!" Mabel called out.

"You haven't seen me, I was never here!" Dipper exclaimed running off.

"Little bit?" Soos asked.

"Mostly it's just because it's funny," she admitted.

Omake - Untangling the timeline.

"So, you attempting to cause an alternate timeline was ineffective because of all the time jumping we did-," Dipper began his voice a bit garbled as he had become a pig and lacked human vocal chords.

"Which would explain why they didn't set guards on me," Blendin figured out. "Nothing I did could affect your timeline from before you started jumping."

"And we are from that alternate possibility," William said. "The probability lines were skewed enough to allow us to move into realized space using a faerie circle."

"Which shouldn't be possible without a major rip in space-time being opened without the outer boundaries being set!" Blendin groused.

"I transformed into a pig to save Waddles, which turns out to be my future self sent back in time and a bit scrambled from traveling that way," Dipper-Waddles reasoned.

"Quantum entanglement," Blendin said. "Used on anyone else they'd have ended up scattered over a decade."

"Mabel, Madelyn, and their fetch have become an insane psionic entity -" William began.

"Known as the demon Bill Cipher," Dipper-Waddles agreed. "As scrambled as I was, I only had one set of memories and personality to deal with, they have it a lot worse."

"And now I'll use this orb of pilfered temporal energy to reset the timeline," William said. "This would normally cause a temporal loop that would repeat endless, however, being psychic, both myself and Madelyn receive information from outside the current timeline, meaning we'll eventually resolve the loop in our favor."

"And you are going to become me, who becomes waddles..." Dipper-Waddles trailed off.

"And Madelyn will become Mabel, who becomes Bill, a being composed of both of them and their fetch," William agreed.

"But they're back in time," Dipper-Waddles pointed out.

"Yes, just as you are," William pointed out. "Bill is currently floating around Gravity Falls somewhere."

"I'm here!" Bill Cipher announced, appearing in a flash of light with a pen in one hand and a diagram in the other. "And I'm as confused as you guys are."

"Does this mean we end up as Waddles and Bill or do we cease to be them to resolve the timeline?" Dipper-Waddles asked.

"Well..." William shrugged. "No idea. Does it matter?"

"Becoming a pig was never one of my life's goals," Dipper-Waddles said dryly.

"So change back," William replied.

"It's not that simple," Dipper-Waddles said with a sigh.

"Have you tried?"

"Well, no," Dipper-Waddles admitted, he sighed and closed his eyes, concentrating on being human again. He slowly shifted forms, obviously straining as he took on an upright posture, losing animalistic qualities until he shouted in triumph, human once more, "Woot!" He danced a jig.

"Shake it baby!" Bill called out before blushing bright red and slapping both hands over where her mouth would be if she had one.

"And now we know how to turn Bill back into the Pines Triplets," William said. "And puberty is going to be kind to me except in the facial hair department."

"Pardon?" the naked Dipper, who'd aged to his late teens asked, too engrossed in being human again to notice his lack of clothes, asked.

"Just do a couple of Jumping Jacks," William said.

"What? No!" Bill exclaimed as Dipper did as requested and she broke apart into several identical women in their mid twenties.

"Someone give me some ones!" Madelyn shouted.

"She's you," one Mabel told the other. "I'm the demon clone."

"No she's you, I'm the demon clone," the other argued both of them embarrassed beyond belief.

"Does this mean the timeline's restored?" Blendin asked.

In a flash of light five Pines showed up, three Mabels and two Dippers, all blond with blue eyes. "We are the five in one," they said in chorus.

"Screw this," William said slamming the ball of time against the bars of his cage releasing the temporal energy.

The five Pines laughed and one of the Dippers took off his wig revealing regular brown hair as the timeline faded. "Man, I had no sense of humor back then."

Typing by: Stephenopolos