Smoke and Mirrors (Yandere!Underswap!Sans X...
Yandere!Swap!Sans X Reader, and a little Papyrus X Reader too :3
"Stay away from me!!" You yell, tears streaming down your cheeks. "Your not Sans! Your Something Else!" You continue to scream as you walk backwards. His dark chuckle echos through Waterfall like church bells, it makes you shiver. The silver back knife he held in his hand grazed against each and every one of his fingers, staining them each the crimson red and the grazle dust.
"Princess..." You could hear the insanity in his voice just by saying just one word. "I am Sans...the same Sans you met, the one who loves tacos, all that! Sweety, its me alright...just the one that's hidden." You feel something cold hit your hands, then your back. He was nearing closer, and you couldn't do anything but sulk back into the deepest part of the corner. He crouches to your level, smiling like a mad man. Him being closer to you, a familiar metallic sent hit your nose, and it made you want to gag.
You felt the need to scream, and he noticed that. He leaned into your ear. "Go ahead, Princess.... Scream. Though only I will hear you because..." he pauses, letting out another chuckle.
"Everyone else is dead~!"
"Sure, OK bro."
"I'll make her mine!"
"Trust me, you'll be mine forever....and I'll kill if I have to prove it."