All things Undertale
185 stories
~Experiment~ {Yandere Gaster X Reader} by WateredDownLemons
WateredDownLemons
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None of the art used in this story belong to me!!! And neither does Gaster! __________________________________________________ You were just supposed to be another shot at making an artificial human soul. But something happens. Something 'He' didn't expect. "How Interesting..."
Gaster x Reader by MoonReader109
MoonReader109
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Pretty self explanatory. This takes place after the Pacifist route in Undertale. Through determination, Frisk was able to bring back Chara, Asriel (Asriel is Flowey per say), and Gaster. I believe that Gaster is the father of Sans and Papyrus. I also don't believe that Chara is evil. The monsters are on the surface, and although they are amongst humans, most humans have accepted them.
Fallen Angel (Gaster x reader) OLD by Feniksiara
Feniksiara
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OLD AND BADLY WRITTEN THE REWRITE IS POSTED ALREADY DISCLAIMER: The god figure created in this fanfic is purely fictional. He is purposefully made to be prideful and cruel and is not supposed to represent any god. I am religious myself and I did not intend to attack anyones believes with this book. An angel. Sign of hope for humans, yet a nightmare for monsters. Powerful, skilled and...beautiful. But what happens when one rebels against the cruelty towards monsters? What happens when she's banished to the underground, only with wings as a painful reminder of who she once was. What if she's found by the Royal Scientist? What if the nightmare every monster is scared about, is just as broken as they are? And what if she'd find something she would never imagine she'd find in the underground...love? *Cover edited by me. The pictures used in the story belong to their original creators. If any of them aren't okay with them being used, I'll take them down* Started: 21.12.2018 Ended: 22.08.2021 09.03.2019-Number 1 in gaster! 07.02.2020- Number 7 in undertale! 25.02.2020- Number 4 in undertale! 15.04.2020- Number 1 in undertale! 11.10.2020- Number 1 in papyrus! 03.06.2021- Number 80 in fanfiction!
What's Up, Doc? | Gaster!Sans X Reader by artsyTrashpile
artsyTrashpile
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------------------------- "Well would you prefer 'glasses' or 'human'?" He smirks. "..." You glare at the smoking skeleton. "Then Doc it is." ------------------------- Things to remember: | Author's Notes (A/ns) are written like this. | | Swearing. No lemon. Just fluff. If lemons shall be added, they'll be censored. Basically lemon-free. | | Story is written in my point of view (author's) and is a slow burn. | | This guide will be updated regularly, so don't forget to check it out every time somethin new pops up. | (Y/n) = Your Name (L/n) = Your Last Name (E/c) = Eye color (H/c) = Hair color (S/c) = Skin color ~~~ = Start/End of Chapter ***** = Time skip '___' in Italics = Thoughts ••••• = :) + ___ + = POV Switch First published on June 10, 2017 Last part published on January 23, 2018 Sequel is deleted. I do not own Echotale, maybe some drawings, the music, or Gaster!Sans. They all belong to their respective authors, artists and or composers. But I do own the cover art, maybe some other drawings, and the story. You? Well, you belong to G.
Faded {Ink!Sans x Depressed!Reader} by Trixbyte0
Trixbyte0
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Short Story Based Song
+13 more
My Greatest Experiment (Skelebros' Origin Story) by ZanaBSparrows
ZanaBSparrows
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After much research and theorizing, I've decided that I'm going to attempt it. It's risky, but I'm so desperate at this point that I'm willing to put my own well being on the line. If I survive, this may just turn out to be very... interesting. This is my thoughts on the origins of Sans and Papyrus, as well as their connection to Gaster. It will be connected to the ZanaTale timeline (or, in otherwords, my Sans x Reader fanfic "When Two Souls Meet"). Loosely inspired by the HandPlates AU by Zarla. Awesome cover image by Dweebycake.
Bruised To The Bone: (Sans x Reader) by sweetisbored_
sweetisbored_
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(Y/N). A peculiar soul; A human core, with a skeleton's power. Her parents are ashamed of her, beating her every time they catch her using magic. One day, she accidentally hurts someone, and they bring her almost to the point of death, trapping her in her room. After the incident, time has begun to reset. Two months pass, and then it all starts over again. After two months, she's plunged into immediate pain and suffering. When she feels like she just can't take it anymore, she decides to take her own life as a sort of experiment. Y/N blasts through the wall, making her way to the chasm, where she hurls herself in.. And wakes up. Almost immediately, she's met with a threat, coming from a flower, no less. She deduces that this must be an evil sort of hell for people like her. People with magic. Her opinion is only further confirmed when she meets a skeleton who wants to kill her for existing. When Sans finds her, he's immediately confused. The absence of Frisk only adds to the confusion. Maybe this human can remember the resets. Maybe she hurt the kid because she wanted to be the most determined. Maybe this is the demon. Without fully understanding (Y/N)'s backstory, he goes after this anomaly in the timeline. He eventually decides that she isn't that bad after all; Just another depressed soul, not unlike himself. The two hit it off, their personalities obviously compatible. But what happens when one of them feels something more? And what happens when an old rival returns? HEADS UP: I really hate when, like, half the story or the whole sequel is full of pure fluff. Once (Y/N) and Sans get together, there will still be relationship drama and story drama and such. ALSO! This story is ongoing. It will have errors. Updates will occur every 2 days, and I won't edit them. Edit: OK. SO. The first few chapters are NOT a good representation of my skills. Once the story is done, I'll probably go back and edit, but for now just know that it gets better. I think.
Lost and found ((Swap!Papyrus x reader))  by ImYourCh_CherryBomb
ImYourCh_CherryBomb
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Well, you know the saying, no good deed goes unpunished. While searching Mt Ebott for a missing child, you and your friends fall into the UNDERGROUND, a place full of monsters, ruled over by an angry queen who wants human souls. A place that, long ago, you yourself had been trapped in. Your choices now will affect the lives of everyone around you, and you'll learn that the best lost and found stories are not about things, but about people.
(Sans x Reader) When Two Souls Meet by ZanaBSparrows
ZanaBSparrows
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Sans has lived through countless timelines. He's seen the kid make friends with everyone, only to give up in the final moments. He's seen the kid killed, over and over and over again. Sometimes, he'd even done the killing himself. And no one ever remembers. Not even the kid herself. It's an exhausting cycle, one that never seems to end. But there's something different about this run. Another human's fallen down... the kid's sister.
Into The Game >> (Sans X Reader) Undertale FanFiction by Melody4164
Melody4164
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It was just a normal Saturday. (Y/N) was playing Undertale for the millionth time. She was obsessed. (Y/N) had played all of the routes. True Pacifist, No Mercy/Genocide, Neutral. She experimented with killing certain characters doing different things. Then, as (Y/N) started a new game, she felt a falling sensation, as if she just fell out of her chair. She blacked out soon after. When she woke up, she was lying on a bed of golden flowers. She knew this place. (Y/N) was in the game. She had taken the place of Frisk and was in the Underground. •Disclaimer I do not own Undertale. It belongs to Toby Fox. I do not own you. You own yourself. I do not own the cover or any of the pictures that will show up in this book• *If you're reading this as a guy please just change the pronouns to he/him/his. I find if a lot easier to just put female pronouns. Thanks! :3 *