Undertale AU Sibling Scenarios

Brotherly! Dusttale! Sans X Sweet! Kind! Child! Reader

Me:  *sitting in the corner, typing quietly*

*You receive your oneshot

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You sat at your brother's post, swinging your feet. He had texted you, telling to wait there for him, given you had gone on a walk and he wanted you to wait for him there. The underground had recently gotten more dangerous, given the human had started attacking everyone. Your eldest brother had to kill to get stronger as well. It was scary, but you were prepared if Sans had to come after you to defeat the human.

It hurt you when he killed Papyrus, but you saw it hurt him as well, so you weren't too scared of your brother. If fact, you remembered wiping away Sans' tears and telling him you weren't scared. That everything would come out okay.

You were torn from your thoughts when a colder-than-normal breeze blew past you, blowing more dust in your face. You grimaced slightly, and waved you hand in you face to dispel some of it. You looked up, seeing it was about to storm. You hummed, hopping up and making sure your footprints were going to be deeper enough to outlast the storm some before you ducked underneath the counter. You dug out your phone, texting Sans exactly were you were. He may not have his phone, which was why you made deep footprints in the snow.

"S-stupid... snow... c-c-cold..."

You perked up, peering over the edge of the counter. You didn't recognize the person, given the snow and dust in the air blocked much of your view.

"If you want, you can take shelter under the counter with me!" you called out to them, your sweet and kind nature getting the best of you. They looked over, and their chuckle made your magic run cold.

"You can't see me, yet you still offer shelter? Oh, how fun this'll be."

You bolted out of your hiding spot the moment you saw their knife. It had to be the human. You screamed, making sure it was loud and clear for Sans to hear from a distance.

"Get back here!"

"SANS!" You cried, trying to lose the human in the trees, "Sans, help me!"

You dodge a tree, only to barrel into another one, stopping dead in your tracks. After a moment, you realize the object isn't a tree, given it wasn't as hard and had dust all over it. You heard the human's feet stop behind you.

The silence was thick enough to be sliced.

You finally gathered the courage to crack your eyes open, seeing Sans' familiar form inches away. You shook, clutching his sweatshirt as you buried your face into the dust-covered material.

"Help..." you whispered, your voice muffled to the point it was hardly audible.

You couldn't tell if he was staring at you or the human, but whichever one it was, he was giving them his famous death stare.

After a few more tense moments, you felt Sans move, and soon something warm was placed over you. You open your eyes, seeing Sans' jacket. As you looked up, he pulled the hood down over your eyes.

"Sa--"

"Run if I say so."

You resisted the urge to gulp - despite not having a throat, and you nodded in response.

"Be careful..."

"I always am."

You ended up having to run, and you were half glad. Fights like those scared you. Since Sans and the human mostly blocked your way to town, you had to run deeper into the trees.

Soon, you saw a large tree with a hollowed out area higher up. It seemed big enough for you to fit into. You climbed, up the tree in seconds from all the time you spend climbing them. Thankfully, the hole was just a bit bigger than you, so you wouldn't be too cramped. You clambered in, curling into a ball and watching for any signs of Sans.

Several minutes passed and you soon saw a figure emerged from the trees. You let out a silent sigh of relief when you recognized it as your brother.

"(Y/n)?"

"Up here!" You called softly, poking your head out of your hiding spot. He looked up, giving lopsided grin.

"There you are. C'mon down, the human got away, but they won't bother us for a while."

You grinned, making your way down with ease. He took your hand when you made it to the ground.

"C'mon, let's go get some nice cream."

"Okay."

"...I'm washing this jacket when we get home."

"Why? The dust is caked into it."

"I was talking about the ketchup stains."

"Oh come on! Those stains took forever to get perfect!"

"What."

"It took me weeks!"

"You haven't washed your jacket in WEEKS!?"

"No."

"EW!"