Yandere Undertale Au's x reader oneshots

yandere underbeats sans x child!reader

A/n: sorry reader-chan if your a child in this chapter but your not a baby bit your age in here is 10

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Sans p.o.v
           I was outside playing my theme like it always happens. It's been week since human frisk gotten us out of the underground and here am i now walking down the streets and listening to my theme, while i was walking i decided to go back home i didn't really want paps to be worry about me again. While i was walking i found 3 boys with one bruised girl 'it's seems they we're bullying the kid' i then rushed on the 3 boys and tugged the first boy was in front of the girl, he turned around "what do you want smiley trashbag?!?" I stand there in a black stare at what did just he called me 'smiley trash bag huh??....' Without hesitation the boy next to the other punches the girl on his abdomen repeated again and again as i stand there like an idiot doing nothing 'what are you doing sans help the freakin' girl!?!?' I then snapped out of my thoughts when i felt someone punccriede in my cheek but i quickly avoid it and rushed towards the girl, i grabbed his shoulder to make him stand up "th-thank you" she stuttered on his words " hey trash what are you doing with that bitch??!?" Wait he called this girl a bitch that's no fun, i summoned some bones infront of them as their faces is full of fear and worry"if i saw you're freaking faces and hear you bullcrap words, y o u ' l l b e d e a d w h e r e y o u s t a n d " i use my deep voice at the end as they run in fear, i sign in relief and walk to home with a beated girl on my back as i gave him a piggy ride since she couldn't walk because of all those pain that she have

°~~ later ~~°

i knock the door and saw frisk "howdy frisk would you call paps? we just have someone to take care off" frisk nodded and go find paps, as i entered and lay the girl on the couch. after a minute frisk entered the living room with pap, as paps rushed on us and pull out a first aid kit and heal the girl,another later the girl was finally healed thanks to paps and frisk

y/n p.o.v

i woke up in a bright room as i jolted out the couch and scan my surroundings to see a human with a light blue sweater with lighted 2 purple stripes and a short brown hair with a purple headsets hanging around his shoulder as she noticed you, the human rushed towards and sat besides you "are you feeling okay now?" she asked, you nodded slowly "hi i'm name is frisk, and you?" "f/n" (a/n: f/n = full name) frisk smiled and helped you to stand up, as you and frisk entered to the kitchen to see two skeletons, the big one rush towards you and grabbed you're hand and shaked it "HI HUMAN I'M THE GREAT PAPYRUS BUT YOU CAN CALL ME PAPS" you giggled on how pap spoke as the other one walked towards you slowly " h-hi i'm s-sans" sans said shyly, you smile and shake his boney hand "i'm f/n but you can call me y/n for short" you let go as sans blush purple around his cheeks "i'm sorry y/n if my brother is like this, he's always shy around new peoples" you nodded and walk over to frisk 

~~~later again brought by your very lazy author~~~（//･_･//)

Sans p.o.v
            Ugh why can't i not stop thinking about of y/n!? Okay sans just calm down. i got up and look for y/n and found her on the living room with frisk and asriel, 'i miss y/n even i just meet her like one minutes ago, such a cute beautiful girl y/n is, her h/l h/c and her e/c is just perfect for her appearance and her smile and laugh are just too cute i want her and nobody can have her away from me.....nobody'

y/n p.o.v
         Frisk and asriel was teaching you about all of the music's that they learned, while they we're speaking a loud noise came from the kitchen interrupt the lesson as you and frisk and asriel hot up and rush over the kitchen to see papyrus dust and scarf, frisk shows no expression and ran away while asriel fall on her knees and cry. You decided to go for frisk and saw him talking to a familiar face like frisk but a different sweater the girl has red pure eyes and a lime sweater with one yellow stripe on the middle, it seems like frisk and the girl was fighting about something

Frisk p.o.v
          "Tell me chara!? Did you do this!? I said stop doing the r-" "I DIDN'T DO GENOCIDE FRISK AND LIKE I SAID BEFORE I PROMISE I WOULDN' KILL ANYONE AND I WOULDN'T DO THAT, FRIS-" chara stop when she look on the other side and glare back on me and dissappear like nothing happens, i looked in the same direction on what chara looked at to see...y/n

Sans p.o.v
          after of killing paps i hid behind the kitchen counter and saw asriel,y/n and frisk rushed towards papyrus dust, as asriel feel on her knees and frisk just run away but my lil' y/n go after him 'good now....' i stood up as asriel stop "s-sans what are y-" he stops when he saw me carrying a knife "why what have you DONE?!!" I began to walk towards him ignoring his words and stab him on his chest and abdomen, her groans are like beautiful rhythms in my ear and i want to hear it again and again but he turn to dust easily 'so pathetic' i stood up and go find the others.

~later~

After i killed all of them all i left is frisk good thing that my lil' y/n is asleep i don't really wanna be caught though. I was finding frisk when i found him in the kitchen doing nothing, i let out a loud sign just enough to make frisk turn around "oh hey sans....i know that you lost your brother and the others i don't know who ever killed them" she looked at me in a worry expression, i let out a small giggle and pull out the knife i use to kill everyone, she looked at me shock "sans w-what are- why do you have th-that knife?" She stutter in his own words and back away a little "well, i don't really care if i killed my brother and everyone. *sign* the reason on why i killed them because there we're in my WAY!! And for you're reward frisk for being in my way to.....you should go to sleep forever " i rush towards him and use my knife to stab him since she was a slow poke, she'll die easily. I pinned him on the gound and use the knife and buried it on his chest and stab it again and again, she groan everytime i stab him until i finally herared him scream 'ahh music to my ears i wanna hear more' i excitedly stab him to where her heart was again and again as she just died and blood was on my clothes, i giggled and stand up 'now time to clean the big mess' i put away the knife and carry frisk body and bump it on the trash but i cut her body into prices before i bump her in the trash with the knife and burn it. After of doing it i change my clothes and find for my lil' y/n to saw him awake "oh hi y/n" i said innocently as she rubbed his eyes "sans have you found frisk?" She asked 'awe those cute vice of her' i thought and hugged her "I'm very sorry lil' y/n but frisk was...gone" i faked my sad expression as my lil' y/n cried and huged me, i hug her back as i grin and whisper something to him "your mine now....my lil' y/n" as i knock her out

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Thanks goodness I'm freaking finish for this chapter and for now on does anyone have a request? Don't worry I'll do you're request and sorry if my English is bad I'm not really good at that much . hope you like the story (づ￣ ³￣)づ