AU Sans X Reader One-shots

Killer x Sister Reader

I'm not great at writing angst but I tried.
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"Killer, can I talk to you about something?"

You stuck your head into his room, awaiting his response.

"You ever heard of knocking?"

"You're one to talk."

He chuckled at your comment and motioned for you to come in, scooting over from his seat on the foot of his bed so you could sit down beside him.

"So, what's going on, something wrong?"

"No, not really. Just, please hear me out real quick, ok?"

He nodded suspiciously and got even more wary when you had to let out a sigh before you started talking.

"So...heh, I know you probably won't like this but...I got a boyfriend. Heh..he...surprise."

Ok, yeah, he really did not like that. He never even liked the idea of you getting a boyfriend, much less you getting one without him knowing.

"What?! For how long?!"

"And this is exactly why I waited to tell you."

Well, you did have a point and he knew it. He attempted to calm down, which didn't really work but at least he tried.

"Ok, ok. I'm sorry.  At least tell me who he is."

"...Nightmare."

You were positive for a moment you had broken him. He was completely speechless and his eyesockets went wide.

"Y/n...you can't be serious. Are you insane?!"

"Wait, Kill-!"

"Out of every guy you could've chosen, you picked him! Why the hell would you pick him?!"

"Killer!"

He continued his ranting, greatly annoying you. He was your brother and you loved him of course, but man did he know how to piss you off.

"Sans!"

His yelling quickly stopped and he looked over at you. You were the only one who still called him Sans, since you...since you were the only one left from home.

"Sans, come on. I'm not a little kid anymore. I can date if I want."

"Y/n, I...I know that, but it's just-."

"You don't want me to get hurt? Sans, I know, but trust me, I've got this."

He opened his mouth to argue but immediately stopped himself, instead he let out a sigh.

"You're...yeah you're right, but Nightmare...he's dangerous and-."

"And a good guy. I know him better than you do, if I knew he would hurt me, I wouldn't have started dating him."

"I know...I know. You'll...you'll be fine, you're a smart girl."

"And who's to thank for that?"

He smiled at you. He was the one who raised you to be the woman you were, he was almost as much of a father to you as he was a brother.

"Besides, it's not like it's someone you don't know, and I'll be right here, I'm not leaving or anything."

"Yeah, but you'll tell me if anything's wrong, right?"

"You say that as if you won't be hovering around us whenever we're together."

He tried to protest, but knew you were right and nodded.

Chances were, you'd be lucky to ever be alone with Nightmare, but you knew it was just cause Killer cared too much.

"Heh, figured. So...you're ok with this?"

"No...but, I trust you, you've got this. I will be having a word with Night though."

You rolled your eyelights but smiled, this conversation had gone so much better than you expected.

"Alright, that's fair. I'll go tell him to expect you then."

You stood up and almost got out the door before you turned around and ran back to Killer, quickly wrapping your arms around him, just like you did when you were younger. And of course he quickly returned the hug.

"Thank you, Sans. I love you, big bro."

"I love you too, little sis, even if you ain't so little anymore."

He released you, expecting to see your bright smile that he'd adored since the day you were born.

But you were gone, like you'd just vanished out of his arms.

"Y/n?"

Nothing.

"Y/n?!"

He could faintly hear someone calling his name, but it wasn't you.

Before he could leave his room to search for you the world went black and next think he knew he was sitting upright in his bed.

"Killer, dude, get up! Nightmare's waiting on us."

He glanced over at his doorway to see Dust, he rolled his eyelights and walked off.

That's when it clicked for Killer, it was a dream.

You weren't dating Nightmare.

He hadn't just talked to you.

You were still dead.

It wasn't the first time it had happened, but it always broke his heart the same way it did the day he lost you.

He angrily wiped away some tears falling from his eyesockets and shifted so he was sitting on the edge of his bed, holding his head in his hands.

God, how he missed you. He protected you so long, stayed strong for you even after losing Papyrus, and it just wasn't enough.

He sadly sighed and stood up, glancing over at the picture on his nightstand, of you, him and Papyrus, back when his life was perfect.

He then grabbed the (f/c) locket necklace sitting next to it, he had put some of your dust in it, so you'd always be with him.

He put the necklace on and held the locket in his hand for a few moments, his way of telling you good morning.

He finished getting dressed and walked over to the door.

Looking back at the picture one last time.

Just like he did everyday.