Undertale AU's
45 stories
Hidden for so Long (Sans AU x Reader) {Remake} by RandomWriter-Chan
RandomWriter-Chan
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Long ago, two races ruled the Earth: HUMANS and MONSTERS. One day, war broke out between the two races. After a long battle, the humans... wait no, the monsters were victorious. They sealed the humans underground with a magic spell. The humans were the ones stuck in the underground but there was a special human, (Y/N) (L/N). Like any other human there, she lived a normal life, making mistakes, having her good and bad moments, and all of that. Her universe was different from the other alternate universes, but it still had its similarities. The Guardian of the AUs, Ink, had never seen her universe until Dream caught noticed of the universe. And with that, Ink, Dream, and fellow other Sanses went to venture on into her universe.... (Remake; V.2)
Interdimensional Infatuation (Sans Au x Reader) by Problomatic_enby
Problomatic_enby
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You sit in a room, it's pale, blue-painted walls, so pale they looked white. A voice spoke, telling you to make a choice, how did this happen? Find love, heartbreak, death, obsession. You wake up in a forest, it's dark, quiet. You glance around. This wasn't going to turn out well. You wake up in a forest, it's snowy, you're cold. You glance around. What was that noise? You wake up in a field, you're under a big tree. You glance around, is this a dream? You wake up, now what? The choices are yours to make, the mysteries are yours to find out. Make the right choices, and survive for all of us. Have perseverance. Have patience. Have Bravery. Have the will to choose. Or A really dark dating sim where instead of the main objective being finding love it's surviving and you're not very good at that :) Beware that this story is interactive and needs comments to continue.
𝐃𝐄𝐀𝐃 𝐇𝐄𝐀𝐑𝐓𝐒 ʚ♡ɞ 𝙖𝙪 𝙨𝙖𝙣𝙨 𝙭 𝙧𝙚𝙖𝙙𝙚𝙧 by Sophiestargamer
Sophiestargamer
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------➤ 𝙖𝙪 𝙨𝙖𝙣𝙨 𝙭 𝙛!𝙧𝙚𝙖𝙙𝙚𝙧 "𝙄 𝙙𝙞𝙙𝙣'𝙩 𝙩𝙝𝙞𝙣𝙠 𝙄 𝙬𝙤𝙪𝙡𝙙 𝙗𝙚 𝙧𝙤𝙤𝙢𝙢𝙖𝙩𝙚𝙨 𝙬𝙞𝙩𝙝 𝙖 𝙗𝙪𝙣𝙘𝙝 𝙨𝙠𝙚𝙡𝙚𝙩𝙤𝙣𝙨." ╭──────༺♡༻──────╮ When a bunch of skeletons gets drop in your home. Turns out to be game characters from a certain fandom you use to be in your cringy phase as a teen ╰──────༺♡༻──────╯ 𝐃𝐈𝐒𝐂𝐋𝐀𝐈𝐌𝐄𝐑‼️ ╰┈➤ ❝ 𝙋𝙡𝙚𝙖𝙨𝙚 𝙙𝙤 𝙣𝙤𝙩 𝙨𝙩𝙚𝙖𝙡 𝙩𝙝𝙚 𝙘𝙤𝙫𝙚𝙧 𝙖𝙧𝙩 𝙤𝙛 𝙩𝙝𝙞𝙨 𝙖𝙨 𝙄 𝙢𝙖𝙙𝙚 𝙩𝙝𝙞𝙨 𝙖𝙣𝙙 𝙥𝙪𝙩 𝙖 𝙡𝙤𝙩 𝙚𝙛𝙛𝙤𝙧𝙩 𝙞𝙣𝙩𝙤 𝙞𝙩. 𝙏𝙝𝙞𝙨 𝙗𝙤𝙤𝙠 𝙝𝙖𝙨 𝙩𝙝𝙞𝙣𝙜𝙨 𝙨𝙪𝙘𝙝 𝙖𝙨 𝙨𝙩𝙧𝙤𝙣𝙜 𝙡𝙖𝙣𝙜𝙪𝙖𝙜𝙚, 𝙫𝙞𝙤𝙡𝙚𝙣𝙘𝙚, 𝙢𝙖𝙮𝙗𝙚 𝙗𝙡𝙤𝙤𝙙, 𝙖𝙣𝙙 𝙨𝙤𝙢𝙚 𝙬𝙝𝙖𝙩 𝙨𝙚𝙭𝙪𝙖𝙡 𝙩𝙝𝙚𝙢𝙚 ❞
Sans Au x reader 「On Hiatus! I apologize!」 by cxx____
cxx____
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You are (Y/N) (L/N). A normal girl that is 18 years old .You have been in a normal life until two skeletons appeared in your mansion........ After that incident, many more skeletons keep on appearing........... Undertale does not belong to me!!! It belongs to Toby Fox and AUs belong to their rightful owners!!! Copyright law: This is a work of fan fiction using characters from Undertale, which is trademarked by Toby Fox. The story I tell here about Undertale characters is my own invention, and it is not purported or believed to be part of Toby Fox's story canon. This story is for entertainment only and is not part of the official story line. I am not profiting financially from the creation and publication of this story. I am very thankful to Toby Fox for his wonderful game about Undertale, for without his game, my story would not exist. Umm....... I'm finished now. Please stop reading the description....... Stop!!!! You're really determined, aren't you? Okay......... Here's a hint You should've stopped by now.
Bad Guys x reader by FoxAngel08
FoxAngel08
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(Y/N) was a normal girl but she was homeless since her parents kicked her out a month ago. But that all changed when Nightmare saw how negative she was. But what happens when all of the bad sans start to fall in love with her? Hopefully you stay to find out.
Show No Fear by Juniperlives43
Juniperlives43
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Aliza has created another reset only this time she isn't facing the horror house alone. He older sister has joined her, however her older sister doesn't seem to be able to show fear. What would happen when Sans meets her? How is she there? *Art and alternate Sanses or undertake universe I guess, belong to their rightful owners!*
Prisoner...? (Bad Sanses x Human!Reader) by ShadowOfFandoms10
ShadowOfFandoms10
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Y/N was a human from a brand new AU...which was practically nothing. They were eventually rescued by the Star Sanses...only to be taken prisoner by the Bad Sanses. What will happen? How would they escape...if they willingly want to? This story was originally posted on Quotev! It will always be updated first there, then here. #1 in #sanses 7/1/21 #1 in #badsanses 10/25/21 #3 in #errorsans 5/9/22 #4 in #inksans 5/9/22 #1 in #killersans 6/15/22
The Definition of Love (Grillby x Reader) by swimsurfsushi
swimsurfsushi
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This is going to be my version of Grillby x reader, I'm sorry if you don't like the ship but I find it kinda adorable. Some limes. Some lemons. Other ships included; Papyrus x Mettaton Toriel x Asgore Undyne x Alphys Sans x Ketchup (I had to lol) Will have some "mature" language, I'll try to remember to put a warning at the beginning of the chapter but you have been warned! Hope you all enjoy!
You set my heart on fire. (Grillby x Reader) by Purple_cat_2030
Purple_cat_2030
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A random Grillby x Reader story I wrote cause I was bored and actually really enjoyed making this. (Y/N) is a 22 year old woman that hates her job and wants something interesting to happen for once in her life. She never knew that going to her bar with her best friend Kattie would finally make (Y/N)'s wish come true. Also (Y/N) is a girl and uses she/her pronouns sorry. You can still read this regardless of whatever gender you are. Swear warning, I guess. Also there will be probably be grammer mistakes. Especially in the first few chapters and I'll probably never fix them cause I'm lazy. Sorry. Currently complete and I spent around 4 months on it cause I take forever to do anything. (39,408 words if your curious, I think, I might have done the math wrong.) (Cover art is not mine!) Edit in 2025: this fic sucks and is full of spelling errors and I hate it but I was also incredibly happy when I made it and I'm mad I'll never be that happy about something that I was making out of pure passion. Wouldn't recommend, but I'm still keeping it up because it makes me happy to think about how I was writing this. I should really make a male reader version now (I don't understand my gender identity anymore and don't know how to express it but I need to write gay fanfiction)
Grillby X Reader by TeddyLiona
TeddyLiona
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You've fallen and you can't get up... (#lifealert reference XD) You dont know where you are. A man made of flames, a couple small children, a child goat, a couple skeletons, and a mother goat happen to be playing frisbee in the field of buttercups you've fallen into. You're stuck here, but it's not all that bad. You have friends, and a new family. Your old one treated you like a Cinderella, with no happy ending in sight, and you're glad you fell down. Then one day... something changed.