(Requested by: @Golden_Swords )

Underlined dialogue = Emotionless Killer!Sans
Bold dialogue = Nightmare!Sans
Broken text = Reader

Narrator's P.O.V.

Empty. The entire AU was empty. Not a soul was spared from the blade of Killer's knife. Chuckling in the distance, was the one and only  puppeteer, Nightmare. Oh how he loved to manipulate the power hungry and the deranged. Killer, who is now as emotionless as ever, was being controlled by that very person. Walking back over to his master, Killer smiled. "Done." Was all he said, though it was more than enough to satisfy Nightmare.

"Good. It took you quite a while to finish. Was there someone that had made it difficult for you?" A slight breeze began. The cool air started picking up dust from the deceased monsters and scattering them all over. Killer shook his head with a large grin. "They were playing hide and seek with me, but it didn't last long. The rabbit had to come out of its hole eventually." Nodding, Nightmare opened a portal to his castle. "Come on. There's no use in staying here any longer."

They both exit the empty AU as it begins to crumble into itself. Nightmare then walks towards his throne room, motioning for Killer to follow. "I have something to show you." These words were very strange coming out of Nightmare's mouth. He has never wanted to show anyone anything, but death and the nightmare's he creates.

This seemed quite odd to Killer, but why would he be afraid? He has no fear. Fear is an emotion and he is emotionless, so fear has no power over him.

Nightmare sauntered towards Killer, holding nothing in his arms. This was extremely confusing. He was laying his arms in a position much like a mother holding a baby, or a crazy lady with one of her cats. "This is (Y/N). She's a Cheshire Cat." Looking closely at Nightmare's arms, Killer sees nothing there. Nightmare then sets down the 'imaginary' cat creature. "Say hi to your new friend, Killer."

"There's nothing there." Nightmare chuckled, causing a deep and ominous sound to a erupt from his chest. "That's just an ability she possesses." Killer then looks back down at the floor, only to notice a strangely colored Cat lying on the floor. "Why are you showing her to me? She would be useless in a fight and would only get in the way." Nightmare then walked closer to Killer, circling him, and started to explain. "She is for you to train. These creatures are very mischievous and can be manipulative."

"Why not give her to Dust, or Horror?" The kitten hissed when she heard those names. Nightmare chuckled once more. "Dust is the reason I found her in the first place. Dust chased her, believing her to be a monster he had missed on one of his genocides." Nightmare then sat on his throne, propping his skull up with his hand. "Horror, well, he would have tortured her for the thrill of it. I have no problem with this, but I want to see if she can be of any use to us. This is why I brought her to you."

(Y/N) then stood on all fours and stretched. She then padded towards Killer, only for her body to start disappear the closer she got, eventually turning completely invisible. "What kind of training am I doing?" Nightmare began to explain how the kitten needed to be raised to be a lure, or distraction for the Star Sanses. Killer enjoyed the idea and could see how it'd be useful, so he agreed, not that he truly had a choice in the matter.

"What a strange creature you are. This will be very interesting."

~Timeskip~

"Ink? I found something!" Dream hollers from inside an abandoned house in Underfell. "It's still alive!" Ink, as well as Blue, came running. "What is it, Dream?" Dream then pointed to something on the top shelf. Ink and Blue looked at Dream in confusion. "Nothing's there, Dream." Dream then looks at where he's pointing and notices the disappearance of the mysterious creature. "But it was right here! I could've sworn I saw some cat like creature laying around up there."

Blue then feels something strange on his leg. "INK? CAN YOU MOVE YOUR BRUSH? IT KEEPS TICKLING MY LEG." Looking down at his leg, Blue notices that, not only was Broomie not the cause of the feeling, but there was nothing there at all. "Blue, Broomie isn't anywhere near your leg. What are you talking about?" Blue and Dream start searching the house for what could be causing these strange occurrences.

Ink, walking out of the house, sighs. "What is going on? First Dream sees something that isn't there, then Blue feels something that wasn't there. What's next, am I gonna hear something that's not there?" "No, I'm here alright." Before Ink could say a word, he's unconscious on the ground. "One down, two to go." Dust, who's working with Killer and Horror at the moment, drags Ink towards a hidden portal to Nightmare's castle.

Running around the house, Blue starts to get scared. 'What was that strange feeling on his leg? Why did it feel fuzzy? What could have done it and disappear so quickly?' Thoughts buzzed through his mind as he kept searching frantically. "I found it again!" Dream yells once more. Blue rushes to the room Dream was in, only to see him unconscious on the floor and Killer standing above him with his large smile. "Oh, how nice of you to join us. I was just finishing up with this one." Blue then summoned a bone attack, holding it readily in his hands. "WHAT HAVE YOU DONE TO DREAM?"

"Hehehe. Oh, he was getting tired, so I put him to sleep." (Killer... You aren't Jeff the Killer.... you're name is just Killer.) Blue's body shivered. "Don't worry. He's not dead, yet." Blue then sprint towards Killer, only for him to teleport out of the way. Blue quickly whipped around, but Killer wasn't there. He wasn't anywhere in the room, but neither was Dream. "You're next." Blue nearly screamed at the whispering voice next to him. Sending several bone attacks towards the direction the voice came from, Blue noticed that no one was there.

Blue quickly sprint out of the house and began to search the rest of the empty Snowdin area. Sprinting around, searching every home, every shop, and every snow poff, but no sign of Dream. Now that he thinks about it, he hasn't seen Ink in a while. This scared Blue to no end. He's been alone once. He doesn't want to be alone, ever again.

"Are you lost, sir?" Blue heard from above him. Looking up, Blue sees a strange colored cat looking down at him. "DID YOU JUST TALK TO ME, SMALL CAT?" Smiling the classic Cheshire Cat grin, the kitten puts a paw over its teeth like it's holding back a laugh. "Of course not. Cats can't talk." The cat says, standing on the tree limb it was just laying on. "BUT YOU JUST DID!" The cat, some twisted way, smiled even wider. The grin seemed so sadistic and had hidden intentions behind it, but all Blue could see was a wide smile. It creeped him out. He looked away, feeling uncomfortable.

"But there isn't a cat there?" Looking back up, towards the direction the cat was standing, Blue saw nothing. "WHERE DID-?" Blue then felt extra weight on his shoulder pads. A strange purr was all Blue could hear. "What...?" Quietly, Blue turned his skull, only to see two glowing, (E/C) orbs floating next to him, and an all to familiar grin. "Don't be afraid." Blue nearly screamed. How could he not be afraid?

Suddenly, he felt an excruciating pain in his skull. "That's the last one." Crawling up the awaiting arm of her companion, the kitten reappeared and laid around his neck. Killer chuckled, picking up Blue's unconscious body and dragged him towards an awaiting portal. Oh, this was gonna be fun.

~Portal Transportation & Teleportation~

Walking into a dimly lit and sparsely decorated room. "You did well, (Y/N). Next time, try to toy with them longer. Make them feel true fear." Giggling to herself, the kitten smiled. "Of course." Killer then sits on his bed, (Y/N) crawling into his lap as he gets comfortable. He then begins to pet the kitten's soft fur. Playing with it between his phalanges. Purring in delight, the kitten moves closer to the skeleton.

"You're so different from other cats. But who wouldn't like a difference like you?" Killer says. Some of the liquid hate in his sockets begins to stop flowing, just leaving him with empty ones.

Change may be slow, but it always comes when you least expect it.

(I hope you enjoyed this chapter! Yes, I am at work, but all the kids are asleep. Luckily I had 75% of this already typed up before today. Again, I hope you enjoyed! See y'all in the next chapter! 💙)