Undertale AU Sibling Scenarios

Nightmare X Little Sibling! Reader X Dream

Me: I had a drawing, but I didn't take a picture of it and can't remember where I put it...

Mistress: *sarcastic clapping* Woooow... such a wonderful job...

Dove: *hits Mistress* it's okay, you can upload it later!

*You receive your oneshot

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

(this may lean a bit more towards Nightmare, but it feeds the plotline~ ^^)

The apple tree glowed with life everyday, but lately it seemed to glow more brightly than normal.

"Brother? What do you think is going on with the tree?" Dream asked, looking up at his brother, Nightmare.

"I'm not sure, let's go investigate."

And so they did, they searched the roots first, and near the front of the tree they found vines, yet the vines were white with black leaves.

Confused, they followed the path the vines made, finding a small nest near the center of the tree. They found a small skeleton hidden in the branches. Carefully moving the branches aside, they saw it was a baby, a few months old.

They were... unique. Half of them was pure black, the other half pristinely white. They had small horns, which matched the bone colors, coming from their head, and small wings sprouted from their back. They were wrapped in a gray blanket with black and white accents. Their slightly clawed hands were curled against their chest.

"Yin and Yang..." Nightmare whispered, the two brothers' sockets widening when the baby opened their eyes. A small white halo came into existence above their head as they turned, gazing up at the brothers with tired, droopy sockets.

Their right socket, which was surrounded by black, was a bright white, with the black yin symbol. Their left was surrounded by white, and was a dark black, with the white yang symbol.

Dream reached in to pick them up, given he was a bit closer, and the two brothers carefully climbed down. Dream had to transfer them to Nightmare's arms so he could climb down from the branch he was on, and the baby was fully awake as his feet touched the grass.

The baby gazed at the two of them, and giggled brightly, reaching out to tug at Nightmare's clothing a bit.

"Is there a name somewhere?" Dream asked, watching as the child turned to tug at his fingers. Nightmare hummed, carefully looking over the blanket they were wrapped up in.

"I don't think so, what should we call them?"

"How about (Y/n)?"

Before Nightmare could reply, you squealed happily before falling into a fit of giggling. You squirmed around happily, your tiny wings fluttering.

"I guess that's a yes." Nightmare said, the two brothers laughing with you.

Later that day, the two brothers carried you around town, pointing things out to you. You squealed and responded in your baby blabber. One time, you had reached out to pet a cat, and you jumped and gasped at how soft it was, jumping in surprise again when its tail swished back and forth. Dream and Nightmare smiled at you.

The next day, you were with Nightmare by the tree, and listened as he read to you.

"What are you doing?" a woman barked as she stomped up to the two of you, "Your not teaching them evil things, are you?"

Nightmare held back his growl, but not his glare.

"No actually, I'm reading them Fluffy Bunny." he replied, showing her the cover of the book, his expression softening at the sight of you poking the rabbit on it.

The woman huffed and walked away. Nightmare glared at her until you tore his attention away by tugging on the book, blabbing up at him.

"Okay, okay, back to the book, I know."

~Time Skip~

It was about a week later, and you had managed to crawl your way to the tree, which wasn't far from where your brothers lived. You babbled absently to yourself, about to settle down between two roots when two hands picked you up. You grimaced at the fleshy appendages, trying to squirm out of their grasp.

"What are you doing all the way out here? Is that Nightmare really that irresponsible?"(Me: Why you litt-- Dove: *holding me back* Calm.)

You started to cry, weakly kicking and hitting the woman's hands when you realized she was carrying you away from the tree.

"Ni-ni! Dre-dre!" you squealed, fear going through you when you were dropped and the woman's gasp reached your ears. You were caught in some sort of magic, and soon you found yourself in Dream's arms. You turned your head when the woman yelped, seeing her in black and white vines.

"(Y/n)? Could you let her go please?" Dream asked softly, glancing up when Nightmare dashed over. You turned back to the woman, and somehow got the vines to disappear. Dream transferred you to Nightmare as the woman stood.

"You irresponsible--"

"You better be referring to me," Dream snapped slightly, his hands on his hips, "I was the one watching them!"

The woman clamped her mouth shut, going pale. Nightmare clenched his jaw to stop himself from smirking or grinning. The woman stumbled over her words, before huffing and walking into town.

"Ni-ni! Dre-dre!" you squealed, wiggling happily in Nightmare's arms. Your brothers gawked at you, but they grinned widely before hugging you close.

~Bonus~ (Me: WOOPWOOP! Mistress&Dove: *letting off confetti poppers*)

"So, what are we doing again?" Nightmare asked, looking unsure.

"Getting along and acting like the brothers I grew up with, that's what!" you barked. Your hands found your hips, and you stared up at them both with a stern expression, despite being the youngest and shortest.

"Do we have to?" Nightmare groaned. You and Dream had managed to help him break through his curse, and so he stood there, in the form you grew up with, not the goopy, ink-covered octopus.

"Yes, now do the get-along hug I talked about!"

"Ugh, fine."

Nightmare more or less hugged Dream, but Dream accepted it and hugged him back nonetheless. You quickly dug out a phone and snapped a picture.

"What are you doing!?" Nightmare growled, pulling Dream off of him without harm to the golden caped skeleton.

"Oh nothing, just posting something to UnderNet."

"OH NO YOU AIN'T! GIVE ME THAT PHONE!"