When your sister Frisk had wrote to you about taking in a feral boss skeleton monster, you didn't believe her. But now that you were visiting and actually staring at the massive creature.. "I.. take it this is Sans.." You murmured breathlessly as you looked up at him. Red slit eyes stared back down, at first in aggression, then bewilderment, finally settling with calm curiosity. "This is him, uh.. he tends to be.. harsh. Don't blame him." Frisk chose her words carefully. "Hello, Sans, I'm [Y/N]. Frisk's sister."
"sister..?" He asked himself quietly. Frisk was startled with how BEHAVED he was being. "Yes. She is my sister and will be sitting in on our lessons today. He grunted. "whateva.."

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"[Y/N]." You looked to the boss monster that you were keeping an eye on while Frisk got the things for their lesson. "Yes Sans?" He tilted his head. "can i sniff you?" Well. That was... an odd question. "Why?"
"curious." Well there was no harm in curiosity, right? "Sure, go ahead.." He crouched over your head, inhaling deeply. He hummed. "'s pretty good." What? You must have asked out loud, because he elaborated. "yer scent. it smells nice."
"Thank you.." You blushed, flustered. "can i feel your hair?"
"W-why?" You were blushing more now. "skeletons don't have hair an' i'm curious." Was his reply. "Go ahead." It's not like he was harming you. So he reached over and ever so lightly started petting you with a large, clawed finger. He was sure to keep the sharp object from scratching you. It felt weird at first, but seeing the content look in his sockets, you decided to let the weirdness to continue. How to pacify a boss monster 101 apparently. "Sans, what are you doing?" He jumped, snarling and moved his tail to protect you. Why? You must have said it outloud again, because he glanced back at you. "i dunno." He shrugged and shifted his tail back into place. "ya scared th' shit outta me though, frisk. don't." She was still as confused as you were. "Mind if Sans and I talk alone for a minute, [Y/N]?" You stood up. "Sure..?"

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You totally weren't ease dropping on Sans and Frisk's conversation. No. Not at all. Pft, yeah you were. You pressed your ear against the door. "Sans, what was that about?" Frisk asked. "what was what about?" Sans grumbled. "Don't play coy with me, Sans. You were petting her and got all protective. What was that?"
"it's a monster thing." Sans growled. "And it is..?"
"none ya business." Frisk sighed. "If my studies on monsters are correct, this would have nothing to do with... soul mates... would it?" Dead silence. "She's your soul mate? Seriously?"
"don't tease!" Sans growled. "N-not.." She was holding back laughter. You, were a blushing mess. You knew exactly what a soul mate was. Now his weird questions suddenly made sense." You walked away from them to recover.

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"[Y/N]?" Frisk called as you came back from your cool down walk. Talk about perfect timing. "Are you done?" She nodded. You came in and took a seat. Sans was blushing madly. "You ok there, buddy?" He coughed. "'m fine, 'm fine." He replied quickly. "Focus on your studies." Frisk mused. You were blushing again. "i am!" He snapped. "Relax, Sans." His eyelights darted to you, then to the book. "sorry." You smirked as Frisk gave you that 'not fair' look. You win.

~Fín~