Sans AU One-Shots

Classic || secrets.

Pairing: Undertale Sans x Female Reader
Prompt: Y/n's up late because she can't sleep, so she goes downstairs to make herself some tea and stumbles across the skeleton that hates her.
Type: late night vibes, cozy, vague trauma, secretive characters
Length: words
Background: The trauma mentioned is kept vague for obvious reasons (it's called a reader insert for a reason), but minor warnings for indirect traumatic discussions.
Notes: Requested by a reader. | This was written at 3 am so the characters act like it's 3 am. I swear it's not purposeful that I write Classic so...wrong, but I'm noticing it's a trend when he's paired with a secretive Y/n. I promise I'll work on something much more in character for him at some point - I'm doing my boy dirty and he deserves so much better 😭

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(Y/n) yawned, rubbing her eyes as her feet took her down the well worn path to the kitchen. She didn't trust herself not to trip, especially when she wasn't wearing her glasses, but the blurry, shadowy stairs were outlined just well enough that she could find them with her sock-covered toes. Her attempts to wipe the sleep from her eyes didn't exactly help – not that her eyes stayed more than a crack open in the first place.

There was a light on in the kitchen, a fact she barely registered as she grabbed the book tucked under her arm and she placed it on the counter to search with half-open eyes for the tea bags. As sleepy as she seemed, sleep refused to take her, stringing her along with the hope that if she just held her eyes shut for 5 more minutes, it would whisk her away to someplace far from here. But like a toxic lover, it taunted her, mocking her with every lost minute of sleep while she falsely believed her inky black escape was right around the corner.

"Can't sleep?" (Y/n) froze stiff, that low bass voice robbing her last bit of haziness, but she didn't turn around. There was a single table in the kitchen, pushed into the corner with two chairs directly across from each other. That was all the skeleton brothers needed, but after Papyrus decided to take the lost human into their loving home, he'd been on the hunt for an elusive third chair that would match the wooden ones they already had. (Y/n) wasn't sure how long it had been, but Papyrus still hadn't found one – not that she felt at home under their roof in the first place.

"Hi, Sans." She knew he could hear the tremor in her voice – how had she not realized he was in here? Her fingers wrapped around her favorite type of tea to pull it from the shelf, dropping it on the counter and busying her hands heating the water as she felt his two pinpricks of light follow her every movement. Sans was the reason she didn't feel at home. They got off on, well, about the worst foot she could possibly imagine, and the immediate lack of trust from both sides put them at odds before they even had a shot at being friends.

The skeleton said nothing as she continued making her tea, and she wondered how rotten her luck had to be to run into him at 3 in the morning. She would've taken Papyrus or even her sibling Frisk over Sans, but of course, life never goes the way you plan. She stayed silent, uninterested in talking with him – especially if he wasn't inclined to even say hello to her. The thing about Sans: she could never tell what he was thinking. She knew he didn't trust her, that he treated Frisk like a buddy and her like a stranger, that he knew her falling into the Underground at all was an accident that no other timeline shared, and he knew about the resets – Frisk repeating the same storyline over and over to get the monsters the happy ending they deserved. This runthrough was slow, but Frisk promised they'd eventually get the monsters to the surface – not that Sans cared, but that meant (Y/n) was left behind under the skeletons' roof until the barrier was broken. (Y/n) could only hope her torment would end soon, but if she didn't know any better, she would've assumed Frisk was taking their time just in the hopes she'd get to know the skeletons as good as they did.