Pacifica

After we lit the scented candles we placed in a circle around Grunkle Stan, I looked inside the journal.
"Everyone, put your hand on his head."
We all placed one hand on his head as I read the incantation.
"Fidentis omnium. Magister mentium. Magnesium ad hominem. Magnum opus. Habeas corpus. Inceptus nolanus overratus. Magister mentium, magister mentium, magister mentium!"
Our eyes all turned glowed blue as our vision faded.

I slowly opened my eyes to see the front of the Mystery Shack. Everything except for me, Gideon, Wendy, and Dipper was in black and white.
"Woah! This is Grunkle Stan's mind?" I stood up from the ground. "Yikes."
The Mystery Shack looked more desolate than usual. Trash littered the ground, and all the trees were bare. Dark clouds covered the sky, and a broken swing set slowly creaked in front of the porch.
"Since when did Grunkle Stan's mind look this dark?" Gideon asked.
"Everybody has their secrets. Let's go and find Will before we see something we shouldn't." Dipper said.
We approached the Mystery Shack.
"WILL!" Dipper yelled. "Come here, now!"
We waited a minute.
"Don't make us go in there, Will!"
After another few seconds, a 2-dimensional blue triangle with one eye, a bow tie, and a top hat floated out.
"M-master!" Will looked surprised.
"Get out of here, now! I never told you to go inside here."
"B-but I made a deal and..."
"I told you to only make deals with MY permission!" Dipper ran and jumped at Will in anger, his fist held out to punch Him. Will suddenly opened up a hole in his stomach and Dipper flew into it.
"Dipper!" I screamed. "Let him go!"
Will looked down at himself and opened up the hole, and Dipper flew out.
"S-sorry, it's just instinct!" Tears flooded Will's eye. "Please don't be mad!"
"Will!" Dipper yelled. "Get out of here now!"
"I-I'm s-sorry, but I made a deal!" He sobbed, and flew inside the desolate Mystery Shack.
"Will!" Dipper screamed, and his amulet started to glow.
"Calm down, Dipper. We'll find him." I reassured him.
"No! Inside that Shack is every memory your Great Uncle has had! Wherever Will is, he isn't going to be easy to find."
"What if we just wake him up?" Wendy asked.
"We can't, unless we unlock a memory that has deep emotions rooted to it. I don't recommend that."
"So we just have to find Will?" I asked.
"Yes. Let's go inside."
We walked up the porch steps, and into the Mystery Shack. Instead of arriving into the small hall, we were in a large room bigger than the Mystery Shack with rooms and hallways branching off. And there were doors.

There wasn't a blank wall. Every space was occupied by shabby, wooden doors. They were everywhere.
"Wow."
"Don't look in any doors, and stay together. It's easy to get lost." Dipper started walking while we all stared in awe at Grunkle Stan's mindscape.
We followed Dipper down the hallway and into a corridor with a sign above it labeled "SECRET MEMORIES".
"Are you sure we should be here?" Wendy asked.
"As long as nobody opens any doors, we should be fine." Dipper said. "We're only here to find Will and what he could be looking for."
"So what would he want?" Gideon asked.
"The only people that know about Will are us and Mabel. You all didn't know about Will before this incident, so it wasn't any of you. I know it wasn't me-"
"How can we trust you?" Gideon asked.
"We can trust him! If he wanted to invade Grunkle Stan's mind, then he wouldn't be helping us." I said.
"So that leaves Mabel, unless someone has found the first journal." Dipper said.
"What would Mabel want from here?" Gideon asked, as a bat swooped down screeching, "NO REFUNDS!", making him duck.
"It seems like she's dead set on getting the Mystery Shack, but why?" I asked.
"I'm just as clueless as you." Dipper shrugged. "So, that leaves our only suspect, Mabel. And why would she want Will to come in here?"
"In Gravity Falls, there's a weird rule that hasn't been changed for years most people don't know about. If you steal the deed to someone's property, it's yours." Dipper said. "Mabel's loophole."
"So she wants to know where the deed is?" I asked.
"Most likely, and how to get it. Knowing her, she probably already knows where it is. But I'll catch Will before he can find whatever Mabel needs."
We continued down the hallway.
"It'll take forever to find Will. We should split up." Wendy said. "This is a long hall."
"You're right. If you find Will, just tell him to get out. He'll listen to nearly anyone. When he leaves, we'll all leave." Dipper said. "And remember, DON'T open any doors."
"Got it." We all split up. I started to run down a hall when Dipper grabbed my hand.
"You'll stay with me." He said.
"Dipper, I'll be fine." I smiled at him. "Don't worry."
"Alright. Just be careful, okay?"
"I promise." I hugged him quickly and ran down the hall.

Dipper

"Where are you, Will?" I called.
I had looked everywhere, and even had run into Gideon once. Still, I couldn't find that isosceles demon. Maybe he was hiding inside of a memory.
I started opening and closing random doors. Nothing very interesting worth noting.
"Will, I won't sentence you to knife throwing if you come out now!"
Silence again, except for a bat flapping its wings.
I opened up another door, but I quickly closed it after scanning the memory for blue triangles.
"Please, Will, just come out. I have chocolate!"
"Chocolate?"
Will peeked around the corner. I smiled.
"Yes. There's lots waiting at home. Lots and lots of yummy chocolate."
"Liar!" Will flew past me, his eye filling with tears.
"Wait!" I raced after him. "I promise I have chocolate!"
He stopped flying. "Really?"
"Yes. Get out of here now and go back to the mansion, then I'll give you chocolate."
"O-okay." Will nodded. "But...I don't know how to get out."
"Just imagine a portal out."
"About that.... I can't really get out until my end of the deal has been fulfilled."