Sans AU One-Shots

Swap || cold.

Pairing: UnderSwap Sans x Reader
Prompt: You're freezing cold, so Sans takes it upon himself to warm you up on your date night!
Type: romantic fluff, literally just a ton of fluff, it'll rot your teeth
Length: 2.9k words
Background: I include way too much unnecessary background in the actual one-shot. Curse me for trying to world build when there's literally no need.
Notes: Requested by a lovely reader 

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The best part about being freezing cold was that you could wear a cute sweater and bundle up like a burrito of blankets and drink hot cocoa to warm up. But that's where the good parts ended. Being consistently freezing was a problem for you, so with your luck, you ended up settling down in Snowdin of all places due to the sweet offer from a certain blue bundle of joy named Sans.

Him and his brother Papyrus gave you a place to stay after you fell into the Underground - which you were more than grateful for, but a small part of you died inside at being stuck in Snowdin which, as the name implies, meant you were snowed in most days. But of course you took it on the chin because in all honesty, you couldn't beat Sans to progress. He captured you every battle you entered with him, and eventually Papyrus suggested you stay over in their house instead of the shed. Apparently all your effort was tiring him out just to watch, but you were fairly certain it had a large part to do with sympathy. By Papyrus' own admission, Sans wasn't going to make it into the Royal Guard even with you captured, so capturing you was pointless - though the bars meant to keep you in the shed were too wide to stop anyone anyways, so that didn't exactly help.

Apparently Sans' HP was too low to join the Royal Guard, but that didn't stop the skeleton from putting in the effort every day to get better. In fact, he took it upon himself after seeing your pathetic display to teach you how to defend yourself. "Weren't you trying to capture me?" you had asked, your HP at a 1/20 as you struggled to stay standing. Your skin was practically blue and you could see your shaky breaths fog in front of you.

"I need to make you stronger so our battle will surely convince Alphys to let me into the Royal Guard!" Sans had shouted excitedly, a finger up in the air with the other hand on his hip bone.

"Ouch," you grimaced. You knew you were pathetic, but he could've just said you couldn't hurt a fly - it would've been less harsh, at least.

"What's wrong, human?" he asked, some of his joy dampening at your reaction.

"I'm not really made for this battling stuff," you admitted, bending the branch in your hand that you'd picked up walking through Snowdin.

"But the other monsters will try to capture you, so I must teach you how to defend yourself."

"Honestly I'm just a lost cause." You'd meant it as a joke, but he gasped and walked over to you, handing you a cinnamon bunny for your HP. You ate it gratefully as he picked you up, walking towards the skeletons' house. Your face heated up and so did the rest of you, your blue body needing the small amount of heat his body provided.

"First, we need to improve your confidence!" And that, in turn, led to him trying his best to get you battle ready. He even let you try on his battle body - made only for the strongest monsters, as you were told by Papyrus - but to your lack of surprise, it didn't make you any stronger. "Then I will have to protect you!" Sans had concluded after all his scheming didn't work. You had looked up in surprise as Paps simply grinned lazily. Apparently the taller skeleton had seen this coming a mile away, though you hadn't the foggiest how he knew Sans would give up all thoughts of capture to instead be your friend. In hindsight, it was rather obvious, but you genuinely thought he only saw you as the missing piece of the puzzle on how to get into the Royal Guard.