Undertale AU Sans x Reader Oneshots

Dust x Reader

(Y/N) POV
I was there bawling my eyes out. "How could I let this happen. I could've stopped them both but I was scared and ran away when it happened. I'm such a wuss. I gotta fix this."

Flash back

"Frisk why did you kill Toriel she didn't do anything." I asked her while my vision was blurred since my I was on the verge of tears. "She told us to prove to her we can protect ourselves." She said with such pride that she killed a monster. "But she was nice. You could've shown mercy like last time." I told while about to cry. "I got bored. And I now realize..." she looks at me with a devil grin. "It's so much fun." She giggled. Where did she go? Where did the Frisk I know gone?

"Maybe you can stop and show some mercy." I told her with a small smile. She frowns. "But that is not fun. Let's continue." She walks ahead. My head drops down. 'Why does she have to do this?' I see the stick. I step over it knowing what will happen next. Later the stick snaps. "H E Y D O N T Y O U K N O W H O W T O G R E E T A N E W ? T U R N A R O U N D A N D S H A K E M Y H A N D." Said the mysterious deep voice. I already it is Sans but I don't want Frisk to kill him or anybody. I walk up to him and shake his hand. Then I hear a fart noise. I giggle. "Hehe the old whoopee cushion in the hand trick. (Skip lines cause I'm lazy).

We get out from behind the rock. "Frisk you are not going to kill them are you?" I whispered to her so Sans won't since he just left. "Yes I am." She says emotionless. (Skip to when you fight Papyrus). We were standing there while Papyrus says his lines. Then we get in a fight together. Frisk takes the first strike. She hits him. It was his turn and we both dodged his attacks. It was my turn and I press mercy. I spare Papyrus. "Lets not fight Papyrus." I said with a small smile.

He didn't listen. They both attack each other while I keep sparing him. He then had little HP. I press spare. He throws more attacks. "Please Papyrus stop." I was on the verge of tears. He noticed but Frisk took one strike and cut off his head. "NO!!!" I run up to his skull and pick it up. "That was unexpected but I still believe in you human. Other human please don't cry." He said. I still kept crying. I hug his skull. Then he turned to dust. I loved Papyrus since he was a good friend in the previous timeline. I collapse on the floor. "Why?" I mumbled. Frisk helped me up.

"Lets go." I then lost all of my emotions. Except for sadness. She continued to kill every monster she sees. I always cry when she does. We completed the genocide and she does it over and over and over again. But this timeline Frisk doesn't wait for me to wake up. I stand up and walk to where Flowey is. He isn't there. I walk up To Toriel's house she wasn't there. I walk out of The Ruins. I see no one in sight. "Hello!" I screamed but nobody came. I continue to walk and I see Sans. I walk up to him but I see him kill another monster. I hide behind a tree. 'Why is HE killing? Also why didn't he hear me?' He then walks away. I hear"Last monster in Snowdin. Now my last destination is Waterfalls. Then to find that kid. I wonder where is her friend though. I could use a lot of XP." I was shocked. I kept quiet. He continued to walk off.

Present

In the first timeline where Frisk did the Pacifist Route I did develop a crush on him when we are all on the surface. I never told him. I guess I should've then huh. I then look for Sans to try to convince him not to kill the monsters in Waterfall. I run to Waterfall. I look for him. Looking high and low for him. 'Where is he? He couldn't have killed everyone in a short amount of time.' I run and run. By now I'm tired and exhausted but trying to find Sans and convince him not to kill Frisk fills you with DETERMINATION. I run more and I eventually find him.

"Sans why are you doing this?" I yell at him while trying to catch my breath. "I have to end Frisk's life. She is a murder. She does this for fun." He Said and turned to me. "Then you are no better then her. You killed mostly everyone." I looked up at him. He had a shocked face but then changed to a murderous one. "It is the only way. I had to see my brother die so many times. She has to die. I also killed everyone in the Underground. When she falls down I will kill her." This shocked me. "She hasn't fallen down yet." "Nope." He answers.

"Why am I here then? I always fall down with Frisk." I question. He shrugs. "Since you are here (Y/N) I need to kill you." He walks up to me slowly. I'm terrified now. He is going to kill me. "But won't she just come back?" I asked him. He stops. "With the fight she is going to get she will never come back." He replied and continued walking towards me. Ok it is now or never. "Sans. Before you kill me I have to tell you something." He stopped. "I love you Sans." I run up to him and hug him. I look up at him with tearful eyes. He widens his eye sockets. "R-Really?" He started to blush. I nod. He hugged back. I cry on his chest. I then feel pain on my stomach. I walk back and see a long bone on my stomach. I look at him with tears. He cries as well.

I smile at him. "I still believe in you Sans. I hope to see you again." I look at him and he is running towards me. "I love you too (Y/N)." Before my life fades away I sit up and kiss him gently. He doesn't hesitate to kiss back. "Bye Sans." I then close my eyes and get swallowed up in darkness.

Sans POV
I watch (Y/N) as she closes her eyes and drifts off to sleep....forever. "I'm so sorry." I hold their lifeless body. "We can be together in the next timeline. Just please come back soon." I lay their body gently on the ground. "I'm coming for you kid." I walk away to Judgement Hall.

I'm so sorry for this I might make a part 2 where only you fall down and not Frisk since she remembers the fight with Sans. Also check out my new book. It is called "You are my Sunshine (Flowerfell Sans x female reader). I just started on it and it might have slower updates. Anyways I will be taking requests don't be shy to tell me some suggestions. Also sorry for doing Dust again. I got a request to do one about NAJ Dust. I was working on this one shot and then got the request. So I'm sorry for doing Dust again.