Sans AU One-Shots

Classic || jealousy.

Pairing: Undertale Sans x Reader
Prompt: You're so busy hanging out with the others that you neglect your best friend, and he starts to suspect something else is going on behind the scenes - and it's definitely not that he's jealous.
Type: serious/scary Sans, lotta excuses and deflection and subtlety, implied smutfic towards the end
Length: 4.3k words
Background: Y'all are on the surface after you broke the barrier - but you spent years upon years as Sans' friend both above and below ground. You take the place of Frisk, if that wasn't obvious.
Notes: I felt the need to have Sans act OOC by portraying him more serious (yeah ik he showed how chilling he can be when he threatens to kill you where you stand in the pacifist run, that's what I'm basing his behavior on). Like yes it's an abnormal situation where he might act like that (abnormal situations are the majority of my one-shots), so maybe I should just claim it's meant to unnerve you and it's intentional (tho ig that's not exactly a lie. Nearly everything I do is intentional). | Keep your eyes up for subtle hints of information; I was trying to practice showing but not so much telling. Requested by a lovely reader. 

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I startled awake, the stark silence triggering unease that forced my eyes to open – like when you fall asleep in a car and wake up when it turns off. The air was still fresh with the smell of popcorn we'd made for movie night, the buttery scent prompting me to look around for the bowl that was once in my lap. It was taken care of – probably so I didn't accidentally spill all the popcorn onto the floor as my body got sucked into the comfy couch cushions – and the house was deathly quiet. Everyone must've gone home.

I leaned back into the couch and stretched, reaching for the ceiling as my tired eyes scanned the dark room. It was nighttime up on the surface with only a single blue light next to me to combat it, a complete contrast to the consistent time of day down in the underground I'd grown almost used to before breaking the barrier and freeing the monsters. That felt like a lifetime ago, and part of me hated to look back on those fond times when I knew I'd never get them back.

"Heya (Y/n)." I blinked, realizing there was a shape next to me I could just about make out. The blue light shifted to two white pinpricks and I froze stiff as I realized who that figure was. The lamp clicked on from the endtable beside him as Sans winked a socket. "Long time no see, heh."

Shame crawled up my spine and made my skin prickle, and I glanced around for any of our other friends that were here not that long ago for our movie night. "Yeah, uh, it's been a while, huh?" I forced a smile that I knew was awkward, my lips shaking a little as I tried to force them into the unnatural curve.

"The others left after the movie – said they had to get home before the storm blew in." His perma-grin widened. "I figured I'd busy myself by relaxing on your couch until you woke up, so they wanted me to tell you thanks for inviting 'em. Papyrus offered to host next time, but you know me, I'm too lazy to host and Paps can't have guests over when my sock on the floor is 'making the living room unseemly', so Undyne called dibs." I nodded stiffly, the next movie night a foreign thought so far removed from why I knew he stayed that I had to wonder if he was just dragging out my torment.

"Sounds lovely." I sounded like I was fighting to get every word out, like simply coming up with a generic reply took all of my divided attention, and he noticed. He let the silence hang in the air an uncomfortably long amount of time – long enough that I started playing with my hands in the hopes he wouldn't realize how shaky I'd become.

"Say," Sans finally spoke, each word slow and deliberate as he pretended to glance up and off to the side in mock thought. "You haven't been avoiding me, have you?" He tilted his head, planting his elbow on his crossed legs while his hand propped up his jaw. He phrased it harmlessly, like he was just checking in, but I knew better.