The House of Undertale AUs

Chapter 4: Gaster!Y/N

Y/N's POV:

It was simple, the merging. Too simple.

All Gaster have to do was literally go into my body. I immediately felt magic within me and my body was already rejecting his presence.

I winced in pain while both of us battle for control. Well, mostly to push Gaster back out.

"Calm yourself, Y/N," I heard Gaster's voice inside my head. I took shaky breaths before finally, Gaster settled in.

"So that's it?" I asked out loud.

"Y/N, you do know you can just think whatever you want and I could hear it right?" Gaster sighed in my head. "And yes, that's it."

I frowned. "That wasn't so bad," I thought.

"The worst is yet to come."

"Thank you, Mr. Optimistic," I rolled my eyes. I went back upstairs and found someone sitting on my couch. Core Frisk.

"Hey, Y/N," she greeted me. "You don't look too bad. How do you feel? And you don't mind wearing black right?"

I narrowed my eyes. "What?" Then, to my head, "Gaster what did you do?"

"Your appearance will change now. Maybe you should go and look at a mirror," Gaster replied smoothly. I groaned and walked towards the restroom.

I looked at myself and gasped. I was absolutely... actually, I don't know (not explaining, look at picture. Yes I know it says Gaster!Frisk but you look like Frisk, so it's okay).

I headed back downstairs and looked at Core Frisk. "One, this feels weird. Two, why are you here?"

Frisk shrugged. "Ink and Error said that they'll meet here with me and you. So, I came but they're not here yet. I wonder why. I didn't even come early (gee Ink you got so busy talking to Frisk and Sans you're totally late to your meeting)."

"Speaking of waiting," I said but then I stopped. Why did my voice sound like Gaster?

"I'm speaking through you," Gaster replied in my head. I sighed. This is going to be really weird.

"Anyways, would you like something to drink, Frisk?" I, or Gaster, asked.

"Tea please," Frisk replied. I hurried over to the kitchen, carefully trying to not trip over my black coat since the back of it is a bit long. When I got a cup for Frisk, I shrieked. My hand had a hole in it.

"Y/N? Are you alright?" Frisk called from the living room.

"I'm fine, just got a bit surprised," I forced myself to reply. I looked at both of my hands. They both have holes in them. I put a finger through it to see if this wasn't a trick. It went right through the hole.

"That's freaky, you know that right?" I asked Gaster. If it was possible, I felt him nodding. Soon, I had tea for Frisk and myself. I set them both down on a table right in front of the couch and I sat down next to Frisk.

"So, we're waiting for Ink and Error right?" I confirmed. Frisk nodded. "Who is Error anyways?"

"Error is basically another Sans," Frisk replied. "He likes to play with his dolls and control them with his blue strings. He can also control a human or a monster just by having string on them and their soul. He also glitches out a lot."

"Makes sense why his name is Error," I snickered. Oh, did I mention that I have really bad timing? As soon as I said that, a familiar while portal opened and in walked Error and Ink.

"I h-heard that, you-you know?" Error said, his voice also glitching out a lot. Frisk definitely missed that part when describing Error.

"Sorry," I replied with a slight grin.

"So, you merged with Gaster?" Ink asked. I rolled my eyes and turned my face to look at him. "Uh, yea. I'll take that as a yes."

"So, what are we talking about?" I asked. Man, although Gaster is a scientist, I felt kinda lazy at the same time. Was it my personality or Gaster's?

"That's yours, although Sans got lazy so I'm not sure."

"Oh my god Gaster. Talk more or else I'll forget about you," I replied sarcastically in my head (whenever you talk to Gaster, you're actually thinking in your head. Does that make any sense?).

"We're talking about how the monster trying to destroy the Pacifist timelines are going to make a move on Undertale very soon," Ink said.

"D-do you have a pla-plan yet, Y-Y/N?" Error buzzed. I took a death breath.

"No I don't," I said loudly. Ink and Error looked at me with surprise. "But Gaster has," I laughed, seeing their expressions.

"Of course-course he do-does," Error mumbled. "So what's the-the plan?"

"Gaster's idea is that there's a hidden building behind my house," I informed them. "That would be where they'll all live. The humans would never find it. It'd actually make them turn back because the mist gave them a spell. Meanwhile, behind that huge house that me and Gaster will make, there would be a place where monsters and humans could live together."

"Why can't the humans over here go there?" Ink asked.

"They're bullies," I sighed. "And I can't let Sans kill them just because one threatens them. It would be a disaster."

"Point taken," Error buzzed.

"Anyways, we could save some monsters and Grillby at the same time," I continued. "So, they could have some friends and Grillby would be there to serve them ketchup and mustard and... Wait."

A sudden thought entered my mind. But then, it disappeared. "Never mind."

"That's actually a good idea," Frisk interrupted. She looked at me with her black hole, err I mean eyes. "But how are you going to do that?"

"Ask Gaster, cause I have no idea," I shrugged.

"Oh, I just have some tricks up my sleeves," Gaster said through me. I grinned as he said this.

(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)(~)

Hello everyone! How are you guys liking the story? I mean, you guys look absolutely amazing once you merged with Gaster. I found this picture while searching up for Core Frisk and Gaster for Chapter 2. Amazing, isn't it? You'll have his powers, his smartness... But I shouldn't spoil the story for you.

I'd like to give my thanks to edkluvff for drawing that amazing picture. And also, I hope you are ready for the AUs. There's so many that I'll be really frustrated if I can't find the picture for it. Well, I better actually get started.

Peace ☮️