AU Sans X Reader One-shots

Nightmare x Skeleton! Reader

Requested by KayMay26

(Reader is Underswap Sans and Papyrus's sister)

"Y/n, I have a question", Nightmare asked while you were sitting under his side of the tree. "Sure, what is it?" "Why do you hang out with me, I mean everyone else is either scared of me or hates me." He was always worries that he'd wake up one day and you would no longer like him, and he'd be alone again. "Nightmare, don't ask stupid questions, I could never hate you or be scared of you", you replied, lightly lifting his spirits. "Listen, I don't care what those others think. I know the real you, the you I wish everyone could see." He smiled at you and hugged you. "Promise it'll always be that way," he asked. "Promise."

I sighed loudly. I promised him, I promised I'd always be there for him, but I wasn't. I haven't seen him in years, I can't believe I just left my best friend.

I wanted to but I was always busy. Work, taking care of my brothers and just life in general. I just miss him. Who am I kidding he'd probably hate me.

I layed back on the couch sighing again, this time catching one of my brothers attention.

"You ok Y/n," Papyrus asked. I nodded, hoping he'd buy it. He knew better but didn't push me any further than that. "Have you seen Sans anywhere," he asked again.

I shook my head and he looked kinda concerned. "When did you last see him," I asked. "Last night before I went to bed," he said.

"He's not at Alphys' or with the queen," he added. "You go ask Ink if he's seen him, I'll ask Dream," I explained. He nodded and teleported to find Ink.

I teleported to Dreamtale hoping Sans was there, Paps and I always were kinda overprotective. I set off to find Dream.

He's gotta be somewhere around here. "Dream! You here," I called out. Ugh where is he. I continued searching but something felt off, like I wasn't alone.

I felt like I was being watched. I was gonna run for it but something hit me on the head. I didn't have any to get away before the world went dark.

I woke up in what looked like a jail cell or dungeon maybe. Initially I was gonna try to teleport but there were some kind of handcuff like things on my wrists that blocked my magic.

I managed to stand up and run to the cell bars to find a way out. But in the cell opposite mine was my brother Sans.

"Sans", I yelled and got his attention. "Y/n, how did you get here," he asked quietly, probably trying not to alert a guard or something.

"I don't know, someone knocked me out when I was in Dreamtale," I answered. "Do you have any idea who did this," I asked.

He let out a small huff and nodded. "I know who it was but you won't like it," he began. "If it was Error I swear, I thought he'd agree to leave us alone," I started. "No it wasn't Error, it was...Nightmare," he said quietly.

Nightmare? But he wouldn't do this, not to me nor Sans. "My Nightmare?" He nodded sadly. "No he wouldn't, he'd never. H-he knocked me out, it can't be him he wouldn't hurt us, h-he wouldn't hurt me," I ranted.

I leaned against the wall not wanting to believe him, not Nightmare. A few minutes later another version of Sans came to my cell. He was the height of classic Sans but with purple and red eyes and slightly gray hoodie.

"Come on, Nightmare wants to see you," he said unlocking the door. I can't use magic and knowing most Au Sans' I wouldn't last in a fight against him so I gave in.

We walked through what looked like a castle to a large throne room. It was black with a dark purple thrown in the middle.

On the throne was a large, inky, black skeleton with one visible blue eye and tentacles on his back. This can't be Nightmare, this isn't my friend.

"Here she is like you asked," the other Sans said while basically throwing me towards him. I fell to the ground trying not to look at him.

"Hey eyes up here," he growled. I reluctantly looked at him. "I don't know who you are, and honestly I don't care. But I know you know my brother and the other Star Sanses."

"If you want to live to see tomorrow I suggest you tell me what you know about them," he commanded. "Never! I won't let you hurt my brother," I barked.

"Brother?" "Yes, and nor will I let you hurt Ink or Dream," I seemed to be gaining his attention. "You can't be related to Ink, and definitely not Dream, so Swap has another sister," he inquired.

"No, I'm his only sister," his eyes widened at my statement. "Y/n, is that really you," he said quietly, hoping he didn't just really mess up.

"Yes, it is. This can't be you Nightmare, you aren't the friend I used to have," I said. "I'm sorry but it is me, I realize I'm not what I used to be," he retorted.

I shook me head refusing to believe it. "No, my Nightmare would never hurt me or my brothers, nor Dream. You aren't my friend, you can't be," he looked absolutely heartbroken at that.

He got off his throne and walked over to me. I expected a punishment of some kind but instead he took off my handcuffs.

"Why, why did you do this," I asked. "If I'd known it was you I never would have," he answered quickly. "I didn't mean that I meant basically kidnapping my brother you idiot," I hissed.

"Y/n please, listen, I'm sorry jus-," I cut him off. "No you listen to me, I know it's been awhile and hell I was gonna try to find you again, be friends again, but looks like that's not gonna happen now."

"W-what," he looked like a kicked puppy. "You heard me, I don't wanna be your friend anymore, not if your gonna do this. You know better than to hurt my family or friends, just leave me alone."

I ran out of the room to the cells and teleported into Sans' cell and teleported both of us home.

(There is gonna be a part two because this is gonna be a long one.)