This Isn't You. . .{Yandere!Underswap!Sans x reader}

[The Death of a Robot]

My god, how did you guys even read this chapter? I read through it and so many things made n o sense-

Also, sorry if the ending sounded a bit confusing :,>

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As you arrived in Hotlands, you spotted the Lab. Tears welled up in your eyes as you remembered what has happened to Undyne. She was so innocent. . .why would anyone kill her?

Sans saw tears fall down your cheeks and took your hand, quickly moving you away from the Lab. You sniffed and glanced over towards him, before blinking your tears away and sighing.

"I'm starting to think that it's all my fault. . ." you whispered. Sans' eyes widened slightly.

"No, no! It's not your fault!" he quickly assured. "You wouldn't cause something like this!"

"You don't know me that much. . ." you mumbled. The two of you continued walking in silence as you stared straight ahead.

Eventually, you came to the NTT Hotel once more, remembering NiceCream. You sighed to yourself once more as you pushed open the doors, holding them open for Sans politely. Then, you headed towards the Core.

You continued to silently venture throughout the facility once more, Sans trailing behind you. Finally, you ended up to the area where Napstaton stood in. He faced you and smiled his characteristic smirked.

"Why, hello again, [Y/n]," he greeted, then looked towards Sans and nodded towards him, adding, "You too, Sans."

"Hey, Napstaton!" you replied, while Sans silently stared back. "Can we go through here? I just want to continue my adventure, so I mean. . ."

"You want to go past me, to Toriel? Why?" he asked.

"I want to see if there's a way I can get you all to the surface. . ." you answered. He blinked, giving you a look that told you you were crazy.

"Really?" he mused, chuckling. "Then you'll have to get through me first. And actually fight back this time."

You sighed once more; you were not in the mood for fighting and you'd rather just get through it peacefully. Sans' watch became more protective by the minute.

"Do I really have to? I mean. . .can't you just let me go through?" you asked softly.

"Nope!"

"Why? I thought we were at least acquaintances!"

"That doesn't mean we can't have a nice battle!" he argued. He did. . .kind of have a point, but you really just wanted to get what you wanted to do done.

"But. . .why? I didn't have to fight Papyrus!"

"He's just lazy."

"Please don't make me do this!" you whined. He just rolled his eyes at you.

"Rules are rules. Now, let's fight, shall we?" He quickly summoned some records, the objects flying towards you. You dodged them. Sans' eye sockets turned black and he slowly began to walk towards Napstaton.

"You won't even have a battle since I'll never fight back!" you told him. He paused his attacks for a moment. This time, you had a point.

"Hah, right. It's never boring when it's a battle with me!" he smirked cockily, and you chuckled lightly in response.

"Calm down there, Napstaton. Your ego is too big for your soul," you replied smartly. Sans paused and looked towards you, his eyes appearing normal, smiling a bit from your response.