(Requested by: @StarryLunar )

WARNING: Slight Gore

The song above: iNSaNiTY

This song will be used during specific parts of the chapter

(The beginning)

"S-Sans? Sans, what are you doing? Haven't you heard? There's a killer on the loose!" (Y/N) yelled to her beloved. His hood seemed to be up and his back was facing her, making it hard for her to see the front of him. "SANS, WE NEED TO HURRY!" As if he had finally heard her voice, he turned around, only for her to scream at the sight.

His once bright blue jacket was now covered in monster dust. The smile she had always loved seeing was now turned into an insane grin. "I-it was you? W-why?! SANS?! HOW COULD YOU KILL ALL OF THOSE INNOCENT MONSTERS?!"

Then, without hesitation, Sans darted forward with his dust powdered knife. The blade was then plunged into her stomach. "I'm the only one who can deal with what's to come. Chara won't let anyone live, so I'm saving everyone."

The once joyful light in (Y/N)'s eyes went out and was replaced with fear and sadness. "How can you save someone that's dead?" Sans doesn't respond and instead pulls the blood-soaked knife from her stomach, stabbing it into her heart next.

"You'll never understand."

(The present)

(Dust's P.O.V.)

"Everything is said and done. Everyone has had their fun. Time to make my exit from this fairytale. My departure was foreseen from the very beginning. Assume the life of insanity, Sayonara." A sweet voice sang off in the distance, though it held an eerie joy to its tone. As the dust and blood-covered skeleton was beginning to move closer to the noise, he felt a cold hand get placed on his shoulder. "Hello, nice to meet you. You seem familiar. Have I met you before?" The words sending shivers down his spine, but there was no one behind him. The hand that he had felt before wasn't there, yet he could still feel its presence.

"Who are you?!" The skeleton yelled, not out of fear, but from anger. Who does this being think they are, trying to scare him, a ghost? He already has one of those following him around. "Papyrus? Do you see anything?" His brother's ghost floated towards him. Papyrus then placed himself into his brother's arms. "I don't see anything that you don't see." He replied. Sans growled. He then felt the presence leave, but the voice returned. "Goodbye, sweetie, nice to see you. Haven't talked in quite a while."

"(Y-Y/N)?" Dust stuttered.

(Major reference to Ava's Demon. I love Ava's Demon. I highly recommend looking it up!)

"Not anymore.~ She died a long time ago, I'm afraid. Oh who am I kidding, I'm not afraid of anything anymore!" The voice coming from her lips was different from what he remembered. "Who are you?" Dust said in a threatening tone of voice, not phasing the female in front of him. "I was the demon always 'haunting' your beloved '(Y/N)'. You killing her made it simpler for us to make a pact. Now, here we are. A not dead (Y/N) and an iNSaNe Sans."

"What did you do to her?!" He hollered, voice dripping with venom and anger. "Nothing worse than what you did to her." Dust pauses and looks down in shame, knowing what he did. "I-I-" "Save it! I don't wanna her it. You killed me and that's that. I can't trust you, Sans! I was scared and you only took advantage of it!" The real (Y/N) yelled out of the demonic body before him. "I thought you loved me... guess you were just using that as a way to kill me easier..."

"Well now we can play your game!" (Y/N) then lunged forward, sharpened nails cutting into the bone of his neck. "iNSaNiTY, the weight of the air is torture." She sang as he was trying to pry her hands from his neck. "Psychopathy, don't know who I am anymore." Her face contorted to that of a psychopath. Blood thirst clear in her face as her grip became tighter. "iNSaNiTY, the illusion of ignorance. Captivity, why don't you take a chance?"

Then there was silence. Nothing was holding Sans any longer. He started to turn around, looking for anything that could have caused this, but there was nothing there. "What.. just happened?"

Papyrus looked up at his brother from in his brother's arms. "Nothing is here anymore, Brother. You killed them all."

Sans looked at his surroundings, only to notice a painting on the wall. 'iNSaNiTY' it spelt out with blood red 'paint'. Sans knew, that whatever just happened, wasn't a dream.

"See you soon, Sansy.~"

(Hey guys, hope you enjoyed this weird chapter I created. It was fun to write, so I hope you enjoy it! Hope you all have a wonderful Christmas week!)