Undertale AU Sibling Oneshots

Underfell! Bros x Brother! Reader

(Some more angst cause why tf not.)

You were always picked on for crying a lot. You'd cry when yelled at, cry when forced to train with Papyrus and Undyne, and you'd cry when the jeers of everyone else got to be too much.
You weren't sure why you'd cry so much, you'd often believe you didn't belong, which lead to you rushing off to Waterfall for a better place. But alas, that plan almost always ended in Undyne bringing your tearful self home per Papyrus' request.
So when news of a human killing monsters began to trickle through town, you stuck close to home, hiding your fear and tears from everyone else.
It was a mistake, for when you finally got the courage to step out, go in search of your brothers, who should've been home by now, you found a gruesome sight.
Sans on his knees, clutching Papyrus' dust covered scarf close to his chest. You stumbled forward, sinking down into the snow next to him.
It was quiet, and for once, Sans didn't pick on you for your tears.

It was your cries that lead Undyne to your sobbing form, clutching your brothers' remains as Sans' dust was carried away by the stream.
Undyne didn't say anything, merely crouching down to hold you for a moment before continuing on, clearly in search of the human.
You wanted to call out, tell her that the human would most surely kill her, but you couldn't find your voice. She wouldn't listen to you anyways.

Many, many more were killed, and as the human reached Judgement Hall, they found you standing there, Sans' jacket and Papyrus' scarf heavy on your form.
"Is this some kind of sick game to you?" You growled out, eye sockets tearful as you glanced over your shoulder.
The human stood there, clothes covered in dust, shoes caked in it, their blade somehow still cruelly clean. Their blade was glinting, ready for its next kill.
"How would you feel if some ruthless killer came along and killed everyone around you?" You turned to face them, one hand clutching Papyrus' scarf, the other tucked into the pocket of Sans' jacket, thumbing across an old family photo you'd found in there.
Silence followed your words. And then slow, calculated footsteps.
"Tch. Right, how foolish of me." You muttered, the emptiness of the chamber making even your quiet voice carry, "Shouldn't expect a ruthless killer to care about anything. Guess I won't have any regrets for this."
Now, your brothers' attacks were calculated in their pens ways, either a test or a challenge to get past. But yours?
Your attacks were fast, a barrage. The moment the human initiated battle, attacks were flying, sharp spear-like bones shooting past you at blinding speeds, cutting through the human's flesh like a hot knife through cold butter.
You were never one for "playing fair" after all, too many others picked on you, heckled you for being weak. So you learned to combat that with cutting corners.
You saw the human bring up their menu, and before their hand could even touch the FIGHT button, another round of attacks were flying.
They were quick to use their attack to deflect yours, and you continued to send attacks their way, hoping to tire them out or catch them by surprise before they could even get close.
As the fight wore on, they didn't tire and neither did you, but they were steadily growing closer to you with each attack.
But, for once in your life, you were confident you could overpass them, you had the most stamina out of your brothers after all. So when the human managed to find a rare gap in your attack, knife poised to strike and cut through you...
You grinned, and teleported away moments before their attack hit.
"Aww, what's wrong brat? Getting frustrated?" You taunted them, grinning at their irritated expression. You hoped it would make them be less calculated, to slip up in their frustration.

* The human says it was fun hearing your friends' screams of pain.

Your jaw creaked as you clenched it. Silently, you ignored them as best you could, they were simply trying to get to you, just as you were to them.
"Then I'll have fun hearing yours, kid." You growled, sockets blank before they erupted in (magic color).

The fight wore on for what felt like hours, and you were beginning to worry as the human was getting closer and closer. And worst of all, you could feel tears beginning to fall again.
You moved to pull back from their attack, but your foot slipped and as you lost your footing, their knife came crashing down in an arch towards you.
As pain erupted in your chest, sharp, jagged bones shot up from the floor, straight into their chest and left them hanging in the air.
You coughed dust, staring up at the human as they went still.
A faint memory came to you, you as a ghost watching your brother fight this same human. But when they died, they came back, standing at the end of the hall.
You wondered if they would come back too, standing at the end of the hall. Walk up to you and watch you wither away with a blank expression before moving on.
But as your body faded, your limbs going numb as the edges of your vision went black, they remained suspended in the air, unmoving.
You coughed again, the force of it forcing you flat on your back, forced to stare at the glittering golden ceiling.
"Sans? Paps?" You rasped, just barely feeling the feeling of hands reaching out to hold you.
Your vision faded to black.

Death was oddly warm, the scent of something familiar in your nose, pulling you from the hellish nightmare of a fight you just fought. The weariness in your body was gone as well, and just as you were getting used to this strangely peaceful feeling—
"(Y/n)! Wake up! Your alarm has already gone off and you should be up by now!"
You jumped, falling out of your bed as you slid off the edge. Shaking, you got to your feet, somehow finding your balance to walk down the stairs, still dressed in your pajamas.
Papyrus stood there, glancing back at you with a slight scowl on his face. Sans stood there too, glancing up from feeding the pet rock.
"Go get dressed in something suitable! We have work to—"
You shuddered, tears falling fast as you sank to your knees, soul clenching in your chest with an aching relief.
Papyrus stopped mid-sentence, glancing at Sans who stepped forward towards your side.
"(Y/n)? You're actin' weird."
"I watched you both die..." you breathed, and Sans didn't waste any time in sinking to the floor with you, Papyrus not far behind. "You both died, a-and then I... I-I... B-But now you're here...!"
Your vision had gone blurry, black and red flooding your senses as your brothers crowded around you.
"We're here, (Y/n)." Sans spoke, letting Papyrus hold you to his chest. "We ain't going nowhere."