Undertale AU Sibling Oneshots

Horror! Sans x Child! Brother! Reader

(Me, glancing at my read count: holy shit nearly 50k...)
Requested by the lovely corvid, @Just_Undertale_Trash!

Sans sighed at another reset, trudging to his post as usual.
Soon enough, he knew, Aliza would come along, and this whole cat and mouse game would start again. Just as he heard the telltale shuffle of footsteps, he looked up, only to freeze in confusion.
Behind Aliza was a smaller skeleton, a bit scuffed and scratched, quietly trailing behind her at a distance.
Ignoring the usual routine, Sans got up, startling Aliza for a moment before he brushed past her, Ace hoisted over his shoulder as he walked up to you.
"Where'd you come from?" He asked quietly, crouching down to your level.
You blinked up at him, smiling a bit as you took in his features with a small tilt of your head.
"Brother!"
Just as Aliza was about to speak, Papyrus cut her off, coming down the path. "Oh good! All three of you are here! Come! We shall partake in the puzzles up ahead!"
Papyrus promptly scooped you up, getting a happy giggle from you as he carried you down the path.
"Sans, something's wrong with this timeline." Aliza murmured, once you and Papyrus were out of earshot.
"What do you mean?" Sans asked, already attached to you.
"Sans!"
With a pop of his neck, he turned to her, a sadistic warning grin on his face as he hefted his axe for a moment.
"Now c'mon, let's go join my brothers."

You sat in Sans' lap, happily picking and pulling on his fingers as he answers Aliza's dumb questions, questions she already knew answers to.
Eventually, Papyrus scooped her up and ran off, leaving Sans with you.
He glanced down at the feel of your hands patting at his face. "What is it (Y/n)?"
You pointed to the jagged hole in his head, frowning a bit out of concern.
"Ah, I'm alright. Happened a long time ago, so don't worry about it too much."
You smiled at that, going back to tugging and picking at Sans' hands and sleeves. You both perked up to a shout of alarm from Aliza down the path, followed by Papyrus shouting to her about whatever puzzle they were on.
"Welp," Sans stood, picking up his axe in one hand, and hoisting you onto his shoulder with the other, "Let's go catch the show, little bro."