Gideon

We entered the damp tunnel, which was covered in grime and moss. Through it, we found a room made out of metal cubes, each bearing an inscription of a letter of some type of language.
"Whoa! Oh man, was this place built in the past or future?" Wendy said.
"Pretty creepy." I said.
"Not as creepy as Gideon's Internet history! Zing!" Pacifica pushed me as Wendy and Dipper laughed, and my foot pressed down on one of the cubes, making it slide down. The letter on it glowed red.
The hatch slammed closed and locked itself, and the walls began to give a mechanical creak as the rest of the letters glowed. There was a loud buzzer, and then the cubes started to move in at different paces.
"What's going on?" Pacifica asked, starting to look panicked as we stepped away from the closing in cubes.
Wendy tried to push in the cubes. "It won't stop!"
"What do we do?!" Dipper cried, as he frantically tried to use his amulet to push the walls back, but they still shifted forward steadily.
I pulled out my journal and flipped to a page labeled 'Security Room'. I held it out.
"Press these four symbols, quickly!" I said, and everyone rushed about the room searching for them.
"One!" Dipper pressed a symbol, and it glowed blue.
"Two!" Wendy pressed another.
"Three!" Pacifica pressed the third one.
I climbed up a set of blocks. "Four!" I called out as I pressed it. On the other side of the room, a door opened.
"Run!" Pacifica screamed, and we ran as fast as our legs could carry us, narrowly avoiding the cubes and throwing ourselves through the door, not knowing what would await us. As I ran out, the last cube closed behind me, catching my vest as I collapsed on the floor.
"Wow! That was crazy! You ruled back there, man!" Wendy lightly punched my shoulder.
"Thanks." I smiled as my heart beat faster than I though it could. Pacifica broke away from Dipper's hug to grab my vest, and Wendy went to the other side of the room to look at a computer.
"Hey, cuz, you forgot this."
Pacifica pulled out my vest, and a crumpled up piece of paper fell out, and she snatched it up and unraveled it.
"Give me that!" I tried to grab the crinkled paper from her, but Dipper used his amulet to hold me back as they both read it.
"Dear Wendy, I have a crush on... Ohmigosh!" Pacifica squealed. "You-"
"No!" I managed to steal the paper away from her and stuff it in my pocket, then I put my vest back on.
"I knew it! You've been acting so funny lately around her, I knew it was love!" Her eyes glittered as they stared off into space, and I knew she was already creating a ship name.
"Were you going to tell her today?" Dipper asked, looking amused.
"No, I changed my mind. I'd just be another guy she hates. Like Robbie." I crossed my arms and looked away.
"You should just tell her! Some way or another you'll feel better after you tell her!" Pacifica said.
"No. I've made up my mind. I can't tell her no matter how much I want to, so just drop it, okay?"
"Hey, Gideon, check out this weird metal closet!" Wendy called me over from the far side of the room.
"This never happened!" I hissed, and walked over to Wendy.

Pacifica

"I think he wants to tell her but he's scared!" I whispered to Dipper. "Poor Gideon!"
"Maybe he needs a little...push?" Dipper smirked, and my head started to fill with a plan.
"Great idea!" I smiled.
I walked over to Gideon, who was talking to Wendy.
"Cuz, whatever happens in there, I just want to let you know it's for your own good." I said.
"Wait, wha-" Gideon's sentence was interrupted by me pushing him into the closet. Dipper used his amulet to shut the door, with Wendy and Gideon inside the closet together.

Gideon

"Pacifica! Let us out!" I pounded on the door.
"We'll let you out, Gideon, as soon as you tell her that thing you've been wanting to tell her!" Pacifica said. "You'll thank us for this later!"
"What is she talking about?" Wendy asked.
"Nothing, she's probably just been hanging around around Dipper too much. You know he gives her evil ideas." I said nervously.
"That's besides the point!" Dipper yelled angrily.
"Let us out right now!" I pounded on the door again. "I might become claustrophobic!"
"Where are the lights?" Wendy reached around with her hand and pulled a cord extending from the ceiling.
Water rained down on us, and we screamed. There was a sudden harsh blast of hot air, and we heard a robot voice say "Decontamination complete."
A red light flashes, and a door slid open into a wrecked room piled with rubble, broken glass, and electrical wires falling from the ceiling and crooked steel support beams.
"A hidden lab! Maybe the author did experiments down here." I gasped.
"What do you think dug all those tunnels?" Wendy asked, pointing to a wall where a large system of tunnels had been dug.
"Let's hope we don't find out." I shivered. Suddenly, we heard a low growl, and a large pitch-black shadow began to cover one of the tunnel walls.
Me and Wendy both ran for the door, slamming our fists against it.
"Pacifica! Let us out! There's a monster in here!" We screamed.
"Nice try, but your only monsters are your own inner demons, Gideon." Pacifica called from behind the door.
Wendy whipped around to face me. "Gideon, whatever she wants you to say just say so she'll let us out!" She said.
"Come on, cuz!" Pacifica squealed.
"W-Wendy, I-I," I thought for a moment to choose the right words, but panic over took me. "I'm going to find another way out!" I grabbed her arm and started to pull her into one of the tunnels.
"Wait, what?" She screamed. "Dude, where are we going?"
"I don't know!" I said, as I pulled her down the tunnel, being careful not to trip over a root or a rock. The shadow grew closer, but then, we saw the shadow of a man begin to fight the creature as we ran into a dead end.
"Back, back!" The voice of the man echoed in the tunnel, as the monster's shadow fell. His shadow started to come toward us, and he approached us, his boots sinking into the soil, and threw down something pink and slobbery in front of us.
"Well, I just ripped out a monster's tongue." He said.
"I-it's you!" I cried.
"Hurry now, I scared it off, but it will regenerate." He led us down the tunnel. "I'm sorry for the state of things, I wasn't expecting guests. I've been down here for years! Weeks, maybe. I miss orange juice."
"You don't understand! You're the guy I've been looking for!" I gasped.
"He's the guy?" Wendy asked.
"He is the guy!" I said.
"The guy?" He asked.
"I've got like, a million questions! Why did you write the journals? Who was after you? Why did you build this bunker?" I asked.
"My boy, I'd love to discuss these matters in time, but we have more pressing matters. It's one of my experiments, a shape shifter. He can take the form of anyone it sees. It broke free from a cage of solid steel!" He pointed to a busted pipe. "But now that you're here, you can help me catch it!"

Pacifica

"Sure are taking their time in there." Dipper said, looking at a lab coat and briefcase I guessed he was contemplating stealing.
"Razzle dazzle! Look at this tubey-thing!" I pressed a button. "Frozen! Unfrozen! Frozen! Unfrozen!" I looked over at a clipboard next to me filled with yellowing papers.
"Huh, look at this." I said, looking at the most recent paper. "Experiment number two-hundred-and-ten, the shape shifter."
"Didn't they say there was a monster in there?" Dipper asked.
I gulped, and my adrenaline started to rush as I felt panicked. "I thought he was just joking!"
"Who jokes about monsters?!"
"Gideon!" I cried.