*Writing these oneshots fills you with Determination 2 (Undertale AU Oneshots)

♥ (US!Sans x Insecure!Reader) [Fluff] [Part 1]

Underswap Sans by BonesTheSkelebunny01 on DeviantArt

Word Count: 546
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You took a very long look at yourself in the mirror, discomfort evident on your face as you poked and prodded at your stomach.  

Sighing, you exited your room and headed downstairs, where the strong smell of tacos came from the kitchen. 

Trying not to make a sound, you quickly grabbed your jacket and headed for the door, but a certain skeleton stopped you.

"Human? Where are you going? Dinner's almost ready!"

You plastered the best fake smile you can manage. "Uh, I'm not hungry, Blue, sorry," you lied, "Everything smells good though! I'll be back in a bit." 

You had usually gone out for walks to clear your mind and relax, trying to free yourself from the self-degrading thoughts you always had. You had only gone as far as Waterfall before heading back. Some of the time, the walks seemed to help. Other times, not so much.

I hate not being able to walk ten feet without losing my breath, you thought, This sucks. You felt hot tears creeping to the corners of your eyes as you walked.

As Sans watched you leave, he couldn't help but worry. This was the third time this week that you've gotten out of dinner. He had planned on asking you about it when you got back.

When you did eventually get back, it was nighttime, or what was considered 'night' in the Underground. All was quiet, so you figured both Papyrus and Sans had gone to bed. 

Going to the kitchen, you noticed that there wasn't a plate of tacos with a note next to it, for there usually was when you left before dinner. 

You were kind of relieved that there wasn't the temptation to keep eating. Despite what your body told you, you claimed not to be hungry.

You gave a faint smile at the thought. The tacos did look good and were somehow still steaming on the plate. Still, despite your stomach growling for the tenth time today, you decided instead to head to bed for the night. You took a quick shower, donned your pajamas, and went to your room.

You sat at the edge of your bed, feeling excessively tired.

To your surprise, there was a knock at your door.

"Human, it's me," you heard Sans' voice from behind the door.

You froze, surprised that he was still awake. A vague feeling of dread loomed over you as you wondered what he came for. 

With a brief 'come in', the small skeleton entered, a look of worry gracing his features, though, you could barely tell.

"Are you feeling alright?" he asked, closing the door behind him.

You nodded, not having the courage to look up at him. Despite your feelings, you tried your best not to look sad.

"Are you sure? That look on your face says 'not so much'."

No matter how hard you tried to hide it, Sans always seemed to look through you and pinpoint exactly what the problem was. Sometimes, you resented that about him.

After a few moments of silence on your end, Blue sighed and came to sit next to you on your bed. 

"Would..," he started, searching your face for an answer, "Would this have anything to do with you not eating lately?"

You flinched.