So...this is my first Gravity Falls fic. It's just a one-shot, and eventually I'll be making a PnF/Gravity Falls crossover. I thought of this recently with the latest Gravity Falls episode, 'Not What He Seems'. I loved it so much! Read at your own risk as there are spoilers to the episode.

I own nothing

Mabel looked desperately between her twin brother and the man she's called Grunkle the whole summer. Both were telling her opposite orders. Both looked equally desperate for her to follow their orders. Her head was with logic, telling her Dipper was right, and that this machine would destroy everything. Therefore, she had to push the button and save everyone, but her heart told her that Grunkle Stan wasn't a bad guy, and he's never hurt her on purpose. The man she got to know throughout the summer was completely different than the man she discovered today. Perhaps this deserved a little looking into. What if this machine was trying to bring something back that was lost? What if Stan had done something to make sure it wouldn't destroy the world or...or...she didn't know what else to think. Dipper was still staring desperately at her, his birthmark starting to show under his hair as it was blown up.

"Grunkle Stan," she said looking away from them both as her hand paused before pushing the button, and she let go of the pole and was too far out of reach from the button. She didn't open her eyes as she flew farther from the button, knowing Dipper was going to glare furiously at her.

"I trust you."

Dipper's eyes widened, knowing she'd just doomed everyone, and he shouted, "Mabel, are you crazy?!"

The rest of what Dipper said was muted in Mabel's mind as the machine hit zero and she could feel herself get knocked out. Dipper too was knocked out, and his last thoughts were panic and betrayal. How could Mabel betray him for a man she possibly didn't even know anymore? Dipper finally felt he could move again, and he could see the portal had fallen. A figure emerged from it, and his eyes widened, not at the figure's six fingers matching the cover of journal number one, but at his sister not waking up. Mabel lied there on the ground with her eyes closed and her braces showing. She doesn't look hurt, but it then dawned on Dipper she was the closest to the portal when it went off. She could have been hit with a lot of pressure or something.

"Mabel!" Dipper cried out, and he climbed over a bunch of debris to get to her, "Mabel, wake up, please wake up, Mabel!"

Mabel remained unconscious. Normally, Dipper would scream at Stan since the machine is what caused this, but instead he just held her in his arms. He didn't care about the author or her betrayal now. He just wanted her to wake up. Take his journals, take his memory, take his soul...just bring back Mabel. Soos could see Dipper holding Mabel, holding back tears.

"Mabel, please. I...I don't care about the journals or finding the mysteries of this place. I just need my sister back!" Dipper cried, and finally he let the tears slip, "MABEL!"

Stan approached the twins in effort to comfort Dipper, but he held Mabel tightly, "No! Stay away from us!"

"Dipper, calm down...please I...I'm sorry," Stan said.

"Mable please wake up, I need you! You're my twin sister...my other half…"

Dipper just hugged his sister, unaware that slowly her eyes opened, "D-Dipper?"

Dipper gasped, "Mabel?"

Mabel looked into his eyes, and they both hugged, "Mabel! Don't scare me like that, darn it!"

"I'm sorry," was all Mabel said.