Rescue (UnderFell!Sans X Reader Fanfiction)

-Prologue-

"(Y/N) slow down! Getting worked up won't help us find Frisk, much less if you get hurt running ahead."

You huffed quietlywere hiking through the forest of Mt. Ebott. You wore a loose sweater, like your company. On it there was a collection of musical notes attached to a (F/C) heart. Your wore an old, faded pair of jeans that had been altered to shorts with boots. Your (H/C) hair was pulled back in a neat way, keeping you hair away from your vision.

You huffed in response, shooting an annoyed glare at the brunette behind you. You slowed your paced and turned, looking back at your two companions impatiently as they jogged to meet you. Rey, your oldest friend, panted as she finally caught up. Her ivy green eyes met yours pleading, evenly trimmed brown bangs clinging to her sweaty face. She wore a thin sweater adorned by a cartoonist heart, gridded in black stitch work. She tipped her shoulders tiredly and dropped her decrepit looking backpack against booted feet, almost collapsing as well. "Finally. I was worried you'd ignore me and just truck on." She sighed gratefully.

"I'm not gonna lie. I really want to." You admitted quietly, cheeks reddening with shame. "But you can't really blame me though."

"No, we can't, but Rey is right. You're no good helping Frisk if you end up collapsing or injured or stuck somewhere we can't help you."

Your focus shifted, landing on your other accomplice. Dash towered over you, a long (nearly flurescent) orange ponytail dangling from a pristine rubber clip atop her head. Her moss colored eyes were plucked into her olive skin, meeting your own gaze with warm sympathy. You could feel your chest soften, realizing you'd been holding your breath.

Cool breath trickled over your lip in the frigid mountain air as you nodded reluctantly. Dash looked at your panting friend, smiling fondly and scooping up the backup as she threw it over her shoulder. Her build was incredibly muscular, giving more to her intimidating stature as what seemed like an Amazonian warrior, but her gentle words were nothing out of the ordinary. As an inherit leader among your group, you couldn't help but follow her instruction.

"If we over-exhaust ourselves then it won't be any use if we find Frisk. We'll be too tired to help him back and we have to be back before midnight or the foster monster will notice we're gone." She debated calmly.

You could feel your throat tighten at the thought of leaving Frisk alone. Crossing your arms, you rebutted with a curt, not so friendly snap. "Come on guys, you can't be tired already! Frisk could be seriously hurt or worse! I haven't heard from his phone and he went missing days ago. That stupid home won't care! We're the only ones here for him. Honestly I don't see what's so hard to understand about my role here." You fumed.

Rey and Dash both seemed taken by your words, frowning sadly at your accusatory stance. Guilt overwhelmed you for snapping at your best friends but you tried to ignore it. You were too worried for your brother.

Frisk had left about two days prior, only leaving a note about some legend. On a mountain, Mt. Ebott, there was a legend of a war that had been centuries long ago. In the war, humans overcame armies of monsters with overwhelming magic and violence and banished the creatures to live Underground so they'd never be a threat again. Apparently he was pursuing the legend of monsters underground for a reason you couldn't understand. Originally you thought the note was a huge joke but when he didn't come back you realized.

"Fine. We'll search for the day, but Ace is waiting back home. I don't want him to get in trouble because I'm not there."

"That's all I'm asking." You said happily.

Dash elbowed you with a smirk while Rey grabbed your other arm. You smiled. "Thanks guys. We better get moving though. I think I know where he went."

You began to walk only to be tugged back by Rey. You looked back at her with a raised brow. She smirked and punched you teasingly.

"We're helping you out (Y/N), but don't expect me to go all wizard of Oz. I ain't singing and I ain't skipping."

Dash smiled and hooked her arm in yours. "But Rey! It's so fun!" She chirped.

Dash pulled you into a harsh skip, dragging you like a rag doll. You squealed a bit, quickly covering it with a laugh. Rey hurried behind you and Dash pulled you quickly over roots and stumps like an Olympic hurdler.

"Slow down guys!" Rey called in between snorts of laughter.

For a few more seconds, Dash pulled you as Rey struggled to keep up. You, getting a free ride, were fine with it. Up until you suddenly hit the ground. A shrill scream filled the air as you felt Dash disappear from your side. Quickly you looked around for your honorary big sister, finding only her fingers as she hung over an abyss.

"WHAT THE FUCK?!" You yelled, rushing to Dash's size.

Dash looked at you with fearful but still smiled. "I guess I was skipping a little too hardcore. I didn't see the giant hole."

You rolled your eyes and grabbed her arm, beginning to hoist her up. "Hey Rey, hurry up! I need help getting Dash outta a hole!"

"That's what she said!" Rey shouted back, reappearing from behind a shrub.

You groaned. "Seriously Rey, are we still eight?"

She snickered. "No, but maturity wise I'm a solid 5... year old."

She darted to your side and grabbed Dash's other arm. On the count of three, you each hoisted with all your strength, Dash was almost up when an extra yelp joined the fray. You looked to your side as the ground below one of Rey's feet crumbled. She looked at you for the moment before she fell. As she fell into the pit, linked by Dash, Dash pulled you down and you all fell.

This wouldn't be fun.