Undertale Spoilers!

I don't own Undertale. If I was Toby Fox, I'd make this a game and not a fanfic.

I retrieved my soul from Gaster's machine and the FIGHT ended.

"Come outside. I'd like to ask you something." Gaster said. He sounded unsure.

I followed him outside, confused. We stood, looking out over the lava. I glanced over at him, standing in front of me.

"You see these cracks in my skull?" He asked, slipping a finger into one of them as he turned to face me.

"I also took part in an experiment. A tiny amount of determination. Smaller than the amount of water inside a pea. We knew from our experiments that different monsters have different tolerances for determination – some could take a whole vial, some could only take a shot glass full before it became uncomfortable. As it turns out, I can't take any at all. Immediately, I began to melt." He motioned to his skull again.

"I would have ended up like the Amalgamates if Alphys hadn't stepped in and frozen the top half of my head with an experimental freeze ray she was going to incorporate into Mettaton's robot body."

"Mettaton?" I asked, vaguely remembering the name.

"The ghost upstairs in the lab."

"Oh." I said.

"Anyway, I have this now." He held out his hand to reveal an odd device attached to it. A flat, circular disc with a button on the side. "I have to refreeze my skull every eight hours. It's become a nuisance. I don't like having to rely on people or on inventions, even my own."

I was confused as to what he wanted.

"I need a human SOUL."

That cleared my question up real quick.

Now I can kill him! I have a reason!

No. I can't.

"Having a human SOUL will allow me to thaw my skull. You don't know how painful it is."

A thought occurred to me.

"Can't you just use the one you have now?"

"Absolutely not. The king wouldn't allow it. But he doesn't know about you."

We were both silent for a moment. I knew neither of us would like what would happen next.

"Give me your SOUL."

"No." I said, my voice cracking.

Gaster sighed. He seemed worn out, tired. He just wanted to be free of pain. There was no evil or anger in his eyes like Asriel.

"Then I'm afraid I'll have to take it from you."

He spread his arms, and in each hand appeared a five-foot-long bone. He then leapt towards me, swinging them at a rapid pace. I was having difficulty keeping up - for a guy who I assumed was pretty old, he moved fast.

He swung his right bone down diagonally, and I slipped under it, grabbing it for myself. I then wrenched it from his grip and tossed it into the lava below. To my surprise, Gaster threw the other one away too. He raised his hand and a giant animal skull appeared behind him – the same attack Sans used. It opened it's mouth wide and I heard it charging.

Gaster must have seen my surprise. "You like it? I call it a Gaster Blaster. I invented them!"

I dived forward, underneath the laser blast. Looking back, I could see that it had carved a trench several feet deep and at least ten feet long. It was considerably more powerful than Sans's version. It also had much more recoil – the blaster ended up roughly three metres behind Gaster after firing.

I had landed close to Gaster and I took the opportunity to grab his arm and twist him into a headlock. My arm was wrapped around his neck and I willed Karmic Retribution to destroy him.

Nothing happened.

He must be innocent. Or I'm healing him.

I also noticed that attempting to strangle a skeleton was not an intelligent move. Gaster threw me over his shoulder and fired another blaster. The beam struck the ground between him and I, and I was thrown further away. I landed on my back and groaned as I felt something break. Maybe a rib.

You see that kind of thing on TV all the time – you know, the hero gets hit by some super powerful laser beam and skids along the ground, eventually rolling to a stop before standing.

That doesn't happen. Not without Karma helping you out. I felt it spread into my chest where my broken rib was, and it slowly began to mend. A gentle glow pushed through my blood-soaked hospital gown.

"So this is the great power of Karmic Retribution!" Gaster exclaimed. "It is truly incredible. I would be honoured to own your SOUL."

I gritted my teeth and stood up. My rib was pretty much done healing.

Gaster summoned more blasters, in a circle around me. I was dead. There was no way I could escape a full circle of these things.

Perseverance.

A thought struck me. I readied my notebook in my right hand. For the first time since arriving here, I had a plan. As the blasters began to charge, I jumped forwards, landing on top of one of them and hooking my left hand into its eye socket. As it fired, the recoil threw me towards Gaster. I swung my notebook as I flew towards him, and it sliced right through his skeletal body. I landed behind where he stood and turned back to face him as he dropped to his knees.

"How… why…" He whispered, looking up at me.

I killed him.

A tiny, nagging voice in the back of my mind told me that was nothing to be proud of, but I ignored it.

He wasn't evil. He didn't do anything wrong. He just wanted to be whole again.

He began to turn to dust, that blew away in the wind.

"what the heck?"

A familiar voice behind me.

I turned to see Sans. Boy, did he look pissed.

Alphys stood in the doorway to the lab.

Both of them were staring at Gaster's dust, floating away on the Hotland convection currents.

Sans summoned a razor sharp bone and threw it at me. I leaned calmly to the left. It skimmed by my cheek, leaving a tiny cut.

"Sans, wait!" I heard Alphys call. "Gaster tried to kill him!"

"no. gaster would never do that."

Sans' voice had a new intensity to it. His eye glowed electric blue. I knew I should be scared, but I stood with a smug smile on my face.

"Nope. Alphys is right, Sans."

Alphys ran up to us, holding a tablet. It showed security footage of Gaster summoning the bones and swiping at me with them. Alphys turned it off.

"You see, Sans?" She asked, turning around to face him. "Huh?"

I turned around to look, and Sans was gone.

Fight scene? Anybody? I dunno, I thought it was okay.

I'd love to hear what you guys thought of it (or any of the other chapters). Feedback is awesome, I'm always looking to improve and stuff. If you want to see more, just press Follow and.. I dunno. I don't follow any stories. I guess you get a notification or something when I update it.

See you on Thursday!