i won't let you leave me【Yandere!Sans x Reader】

Out of Tune

"__________! Sans isn't responding!"

You spun around, eyes wide at the frightful tone. While you had been laughing with Frisk and Papyrus, something had gone terribly wrong. The rising static that lifted the hairs at the base of your neck gave the reason. Frisk looked to you with a gaze you couldn't decipher. Papyrus, though, grabbed your hand and quickly brought you into the living room. You turned to face the brown-haired child, met with a blank gaze in return.

"My child, please!"

Desperation. Papyrus stopped abruptly making you bump into his back. You went to look around him but were surprised when Papyrus stopped you. "HUMAN. SAVE HIM," The tall skeleton looked down at you with a shaky smile, the hand holding yours trembling, "DO NOT BE AFRAID OF MY BROTHER."

"Why would I ever–?" His eyes lit for the first time, letting you see what was held in those usually empty sockets. Papyrus shook his head, looming over you and yet still seeming so small. He looked like he wanted to say more but instead pulled you out from behind him so you could see. Now you understood.

Tears dripped down your own face.

You weren't afraid.

You were devastated.

Watching was all you knew to do. Toriel, the wonderful woman you had just met, was fending off bones with fire. Her gaze was hesitant yet desperate. She didn't want to hurt him. Not when he wasn't even himself.

But Sans had no qualms. His right eyelight was that blue surrounded by red–the other empty. The grin he wore was there and strained to the point of cracking. The magic was pouring out of the empty socket, him yanking down on it as he raised the other to send a flurry of more bones at the goat mother.

Everything in you told you to go to him; to stop him. He wouldn't hurt you. You knew that but still, seeing him this unstable wasn't something...it wasn't something you were prepared for. You'd seen him break down before–but there was always an empty look on his face like he wasn't awake. A look he didn't have now.

What happened? Sans, at least as you've seen, doesn't attack unprovoked. Did she say something wrong? Did he misinterpret any words she said? What could possibly be the cause of this bad of a reaction? You turned, hoping to find Papyrus for support, but wavered once meeting the eyes of Frisk. They stared at you. Vacantly. Papyrus wasn't there anymore, and the front door slammed shut. "He went to get help." Frisk simply said.

The kid was observing you like they were trying to decode a puzzle. You remembered them being flung into the wall yesterday when they tried to approach Sans. If you tried to do the same, would you...?

"You should probably do something about that, SS." Frisk jutted their chin out toward the scene before you, "Toriel can't hold on too much longer."

"SS?"

"Sans' soulmate. SS. Easy nickname." Frisk shrugged, completely relaxed as though nothing was wrong. How old was Frisk? They looked much younger than their voice sounds. You were pretty sure they were barely a teenager.

Their brown eyes met yours, the childish glow nowhere to be seen. "I don't know how," you regarded their statement earlier about doing something, "I don't know what to do to help him." Frisk tilted their head, hair falling in front of their face. They were looking up at you, but you felt significantly lesser under their gaze.

"Just go up to him, snap him out of it like you did last time."

"Last time was different!" You said. You could feel the pressure in the air. Toriel was attempting to reason with Sans, while said skeleton was possessed by an aura of madness you'd never seen. Papyrus told you to not be afraid. "Last time he wasn't...like this." You searched for the word to describe his state.