Dipper's P.O.V
Dipper sat on a decomposing stump. He couldn't believe it. His best friend, his twin sister, his other half, erased from existence. She was always there for him and now he was alone. (A.N: insert forever alone meme here.) His face was wet with tears. All he'd endured with Mabel. He wished Bill had sent him to a universe where tacos didn't exist or where a monster would chase him or where he was at school naked on stage. Nightmare-y stuff. But this was torture.
"Kid, you okay? You totally ignored my high-five." Wendy sat down next to him and handed him a Pitt Cola. "Talk to me bro."
"Mabel IS real. She's my sister." Dipper rubbed his eyes.
"Tell me about her." Wendy popped the cap of the soda can open.
"Mabel has a pet pig named waddles. She loves goofy sweaters and has about twenty summer crushes. She can be a handful at times but we always make up in the end." Dipper said as he sipped his soda.
"Maybe it's time to let her go." Wendy said.
Dipper cringed. "You don't believe me. You think I'm making it all up! That she's just my imagination!"
"You're a kid, it's okay to have imaginary friends."
"SHE'S NOT IMAGINARY!" Dipper yelled. He tore through the woods. Trees flashed by him before he tripped over a rock. "Ow!"
Someone stretched their hand out to him. He took it and looked up. Castiel pulled him to his feet.
"Dipper, you need to hurry. You have precisely...29 minutes and 34 seconds left you need to find Bill and-" He disappeared. In his place was a sticky note.
"Enough cheating. I'm shortening your time to ten minutes. -Bill"
"Okay, find Bill, get Mabel back. Find Bill..." Dipper chanted to himself over and over as he headed to the shack.
He scanned for anything out of the ordinary. The shack waw quiet. Where would Bill hide? Possession? Everyone was acting like they normally would.
Then Stan dropped a snow globe. "Mother of- oh, Dipper. Uh, carefull of the glass. So I was a bit harsh earlier. I had an imaginary friend when I was your age. Enough sap, get the broom."
Dipper grabbed the broom and handed it to his great uncle. He scanned the shelves with little Mystery Shack snowglobes. One looked odd. Every triangle on the building had been replaced with a Bill Cipher.
"I'm coming Mabel..." Dipper picked up the snowglobe.
"Kid no!" Stan yelled.
Time seemed to slow as he dropped the small bauble. Glass shattered sending water everywhere. Then the world around him went black.
~~~~~
Dipper rubbed his eyes. He was in his bed.
"Dipper! You're awake!" Mabel hugged her twin. Dipper squeezed her.
"I thought I'd lost you."
"Please Cheese-Dip. You can't get rid of Mabel that easily."