The Golden Soul [Sans X Reader]

The Lab

     You both decided the next day that you'd meet Undyne and her girlfriend, the royal scientist, Alphys. Sans had said Alphys was trying to find out how to leave the underground without any human souls.
   "But wasn't the last human the seventh soul? And don't you only need seven?" You were confused.
  "The seventh human, Frisk, made all the souls disappear. No one knows what happened to them. So I told her I'd help her, and you could help too." Sans said as you both left the house and teleported to the lab.
  "Wow, its huge." You said.
   "That's what she said." You both laughed at Sans comment.
   "Yup, I walked right into that, didn't I?" He just smiled in response. You both entered the lab and were greeted by Alphys. She seemed very shy and nervous.
   "H-hi Sans. And n-nice to me- meet you --"
   "(Y/n)."
   "(Y/n). Right, s-sorr-ry. I'm Alphys, a-and this i-is Undyne."
   "Hey, what's up punks!"
  "Hiya Undyne. Whats the progress?"
  "Well actually, the progress is none. We can't find out how to make a fake soul. But Alph thinks that if we can use (Y/n's) soul then we can try to make a fake one."
   "What do you mean use my soul?" You felt scared.
   "I understand what you mean. You need to extract some of what makes up her soul right?" Sans asked putting on a lab coat.
   "Y-yeah. A-and I can tr-try t-to m-m-make a case f-for a-around the soul."
   "Hey wait Alph, we can't do this without
(Y/n's) permission." Sans said looking at you worriedly.
  "Wait, so, I have to decide what you guys do?" You asked.
   "W-well, I mean, w-we can d-do it w-w-without y-your soul. B-but it would take a-a v-very long time."
   "...I'll help. I don't want you guys to be trapped down here forever." You said as you looked at Sans.
   "Great! We should start right now!" Undyne said raising her hands in the air happily.
   "We should go to the true lab." Sans said leading us to the bathroom?
  "It's not really a bathroom, ain't that right Alphys?" His eyes went dark and Alphys looked down in shame. You all headed down together. Alphys and Undyne led you all to a room filled with beds.
  "S-stay h-here. I-I'll be r-right back with the tools." She ran away, and Undyne followed.
   "I'm not sure how to feel." You said as you sat at the edge of the closest bed.
   "Don't worry, I'll be there with you, I'll just have to close my eyes I guess." Sans blushed.
   "Why? Is it weird to see my soul or something?" His blush grew darker.
  "Oh..." you said. Alphys came back with a big needle and a empty tube you guessed would hold the extract.
  "Ok lay on your back and just try to stay calm, it'll hurt more if you tense." Alphys lost her stutter. Your soul was pulled out and a golden light emitted from it. Sans looked away from your soul and looked at your face instead. He held your hand tightly. The needle entered your soul and immediate pain hit your entire body. You tried to scream but nothing came out and you soon passed out and the last thing you heard was Sans saying,
   "I'm sorry (Y/n)."