Gideon

"Come in, I apologize for the state of things!" Me, Wendy, and the author walked into another tunnel. "The beast must have some type of weakness we can exploit. I just wish I had my research, but I lost my journals so long ago."
"Journals?" Wendy asked. "Gideon found one, and so did Dipper!"
"Really?" The author asked.
"Yeah! That's how we found you down here!" I took out my journal and handed it to the author.
"Could it be?" He started flipping through the yellowed, frail pages, intrigued. "Yes, after all these years..."
"Isn't it amazing we're meeting the author?!" I asked Wendy. She was examining a discarded empty can when she froze and showed it to me.
"Gideon, look." She whispered.
I looked at the can. There wasn't anything special about it. It was just an old can of beans with a man and a dog on the front.
Except... the author looked like the man on the can of beans.
I gulped nervously. "You know, we should probably get going. Can I have my journal back?"
The 'author' twisted his head to look at us. "You're not going anywhere." He said in a deep, raspy voice.
He crawled up the wall and transformed into a large monster that looked kinda like a slimy maggot with a pinkish tinge, sharp teeth, spider legs, and large eyes.
Me and Wendy screamed.
"So, how do you like my true form? Go on, admit it, you like it."
"You! What did you do to the real author?" I demanded.
"You'll likely never find out. That six-fingered nerd hasn't been himself in years! But I thank you for bringing me his journal. He used to write in it while I was in my cage. So many wonderful forms to take." He transformed from a Gremloblin, to a gnome, and a hide-behind, chuckling at each shift.
"We gotta get the journal back!" I whispered to Wendy.
"Hey body-snatcher, snatch this!" Wendy threw the empty can of beans at the Shapeshifter, which he roared at and dodged easily, then he turned into some sort of frog monster and dropped the journal, allowing me enough time to snatch it up,
"Run!" I screamed, and me and Wendy ran down the tunnel. As it chased us, it turned into a large rolly-polly, rumbling the ground as it rolled after us.
We came to where the tunnel split into two, and I turned on my flashlight and threw it down one of them, then I grabbed Wendy's hand and ran into the other, while the Shapeshifter went after the flashlight. We were running when we crashed into someone.
"Pacifica! Dipper!" We exclaimed in relief.
"Wait, how do we know they aren't the Shapeshifter?" I stepped back cautiously, in a fighting stance.
"I'm not sure. Pacifica, inspect my shape." Dipper flexed his arm and Pacifica giggled, blushing, as she touched it.
"Okay, definitely not the Shapeshifter." I said, as I made a mental note to delete that out of my head. I looked over at Wendy. "Wendy, you're bleeding!"
"It's just blood, man. Stay calm." She took off her leather jacket and ripped off a sleeve to wrap around her injury to place pressure and stop the bleeding.
"What happened?" Pacifica asked.
"We got attacked by the Shapeshifter." Wendy explained. "He broke out of his cage, pretended to be the Author, and wants our Journals."
"What do we do? If he gets out, we could never trust anybody." Dipper said.
Trust no one. The words of the journal played like a broken record in my head.
"He took us, tricked us, and tried to destroy us." Wendy finish tying the jacket sleeve on her wound. "I say we return the favor."

Pacifica

"REVEAL YOURSELF, YOU SINGLE-FORMED HUMAN WEAKLING!" The Shapeshifter shouted from down the tunnel. Yep, right cave.
"Now." I mouthed to Gideon, and he quietly nodded, and we both walked out on my cue. "Boy, Gideon, that journal has some great monsters."
"There you are!" The large, white creature apparently called the Shapeshifter turned to us, and smiled. "Ooh, and a new form! Which should I take? One.." He turned into me, "or the other?" He shifted into Gideon. "How about both?!"
He turned into a large deformed spider that looked like Gideon and I's faces mashed together into a spider with a large, gaping mouth in the center, with rows and rows of sharp teeth. The Shapeshifter let out a huge roar, and that's when me and Gideon started running. We ran down the tunnel, where Dipper and Wendy were standing by an intact pipe.
"Now!" Gideon screamed, and they both turned the rusted valve as the ancient metal squeaked against each other.
"It's not working!" Dipper said, as the Shapeshifter rounded the corner and ran toward us, screeching.
Wendy stopped trying to turn it and grabbed her axe to distract the Shapeshifter. As she wielded it, Dipper used his amulet to build up water pressure and burst the pipe, flooding the room with water, which lifted us up for a couple of seconds.
Amidst all the confusion, after those few seconds the water started to drain out and I landed safely on the damp dirt, coughing out some water I had accidentally drank while trying to swim the current while I gasped for air. Dipper ran over to me. I guessed he had used his amulet to levitate himself above the water because his clothing wasn't dripping wet.
"Are you okay, Pacifica?" He asked, kneeling down next to me. I nodded, and frantically looked around.
"Where's Gideon and Wendy?"

Gideon

Eventually the water level decreased down to a couple of puddles as it flooded down into the drains. I slowly sat up, taking my soggy hat from next to me, when I spotted Wendy's axe laying on the ground.
"Wendy!" I gasped, picking up the axe in my hands, and running down the tunnel, to where I saw Wendy laying on the ground, unconscious. I knelt down next to her.
"Oh, no-no-no! Please be okay!" I shook her arm, but it dropped to the floor. There was no response. "This is all my fault! If I had told you when we were in the closet we wouldn't be in this mess, but I was too scared and you could be hurt or worse, I never even got to tell you..." I took a deep gulp of air. "That I'm in love with you, Wendy."
"Um, Gideon?" I heard Wendy's voice from behind me.
I turned around to see Wendy standing behind me, awkwardly.
"Wait, if that's you, then who's-"
I was interrupted by the Shapeshifter growling and leaping up, grabbing my journal that I had dropped. Wendy tried grabbing it, and they both started fighting for the book so intensely I couldn't tell who was who.
"Give me back that journal!" One of them said.
"Never!" The other said.
"Get off me!"
They both pulled at the journal. I approached them, axe in hand,
"Get her, she's the shapeshifter!"
"No, she is! Hit her with the axe!"
"I don't know who's who! Give me a sign!"
One of the Wendys winked, and the other made the lips-zipping motion.
I dug the axe into winking-Wendy.
She, or the Shapeshifter rather, roared out in pain as green blood oozed out and it turned into its true form.
We pushed the Shapeshifter down the tunnel and into the abandoned laboratory, where a tube that looked like it had been recently used said "READY". We pushed the Shapeshifter in, and before it could crawl out, the tube closed and locked shut. Fog clouded the glass as the Shapeshifter quickly started to freeze.
"Frozen!" Pacifica cheered from inside the control room. Her and Dipper ran out.
"NOOOO!!!" The Shapeshifter shifted into many forms, banging on the glass with arms made of items from rock to fire, but nothing worked. He was. Slowly. Freezing. "LET ME OUT!!" He turned back into his true form as he froze as a layer of ice coated him.
"Yeah!" Pacifica high-fived me, and Dipper smiled in pride. Wendy gave me a fist bump.
We were about to turn around and leave when laughter came from inside the tube.
"You think you're so clever, don't you Gideon?" He cackled. "But you have no idea what you're up against. You will never find the author, and if you keep digging, you'll meet a fate worse than you can imagine. And this will be the last form you will ever take!"
The shapeshifter turned into me, and assumed a position of agonized screaming while he finally froze for real.
We all stood paralyzed in shock, only the silence of the machines whirring and the drip of water.
"Good luck sleeping tonight." Dipper teased.

We went back outside, above ground.
"Man, it's nice to feel fresh air up here again. It was kinda musty." Dipper said as he and Pacifica walked away together. "How long were we down there?"
"Enough time for breakfast! Syrup on cereal!" Pacifica cheered, and they both laughed.
Me and Wendy were left standing in the clearing.
"Look, Wendy, in the heat of the moment, I might have said some dumb things, and..." I nervously rubbed my arm, embarrassed. "Can we pretend that never happened?"
"It's okay, dude, I've always known." Wendy said, calmly.
"Wha-how?!"
"Well, it's one thing for Pacifica to shove fan art of us in our faces, but I always see it sticking out of your pockets." She said.
I groaned, and sat down on the log.
"Gideon, I'm flattered, but you know I'm too old for you, right?" She said. The inevitable words.
"Pacifica said confessing would make me feel better." I said. "So why don't I?"
"Let me tell you something. This summer was super boring until you showed up. If you guys ever stopped being my friend, I'd like, hurl myself into the Bottomless Pit!" Wendy smiled.
"So things won't be too awkward?" I asked her.
"I just wrestled myself, dude! That was awkward." She chuckled. "If you can handle that monster, you can handle a little awkwardness."
"So...friends?"
"Yeah man!" Wendy pushed me off the log jokingly, and laughed. I smiled. "I gotta go. Your place for movie night next time, 'Kay?"
She grabbed her bike out of the brush and rode away, helmet strapped on, leaving me sitting in silence, watching the fireflies.
"Soo...how'd it go?" Pacifica popped out from behind a bush, startling me.
"Wha-how did you hear?" I asked her.
"Everything, all the time." She teased.
"I may have taught her how to stalk!" Dipper called out from behind a tree.
Face palm.
"How can everything be so amazing yet so terrible at the same time?" I asked Pacifica.
"I'm sorry for pushing the shipping a little hard, but I'm working on a list of potential crushes for you!" Pacifica took out a piece of paper and elbowed me. "How about Lazy Susan?"
"Ew, Paz." I said, and laughed. Her and Dipper came out of the bushes.
"I wish we had found the author." Dipper sighed, taking out a briefcase I had seen in the lab. "I stole this, at least."
The briefcase flipped open to reveal an old laptop inside, and we all gasped.
"It's really busted up. It may not work." I said, skeptically.
"Don't worry! I can fix it up good as new!" Pacifica took the laptop from me. "I probably have the parts somewhere."
"This could be our next clue!" I exclaimed. "We're one step closer to figuring out the author."

Mabel

"We're one step closer." I told Will. "All we need is for it to open."
I looked up at him, as he floated above the ground. "Make sure nobody, and I mean nobody interferes. Keep a close watch on the Southeasts."
"Y-yes, ma'am." Will obediently nodded.
I turned away from him, smiling.
"Soon, the world will be mine."