Gaster Stories

This story takes place after the events of the pacifist ending of Undertale, where all the monsters have already left the underground. However, that won't stop problems from starting again; Frisk and his friends will have to face a new threat. DISCLAIMER: This story is based on the fact that the first human fell underground in 2015 and the last in 2060. Here, Deltarune is a sequel to Undertale; therefore, Posttale is not a copy of TobyFox's creation, but an adaptation, or what is also called an "AU." Because of this, there will be things that are different from canon and adapted to my personal preference, with no intention of disrespecting anyone; for example, the gender of the humans: Kris: M Chara: F Frisk: M Don't like it? You can leave. Understood? Great. Contributors: @Fwrevy #Deltapad • Undertale and Deltarune are property of Toby Fox. • Images used in the story are property of their respective owners or made with AI. *#27 in the "Undertale" category 6/13/2026* *#3 in the "Deltarune" category 3/3/2026*

WARNING: THIS CONTAINS HIGHLY MATURE CONTENT (BLOOD, VIOLENCE) READ AT YOUR OWN RISK Money can change a lot of things. It can even change your destiny. Plunge yourself into a life of romance, science, disappearance and misunderstanding. ________________ "When you get better, I'd like to kiss you" ... Gaster only wanted to conduct an experiment. He surely didn't want his life to be taken over by weird feelings. He also wanted the only thing he couldn't really have. He wanted you. What will he obtain? Will his research finally be completed? Or will he have to start another one? As for you, will you be able to move on from the past? Words count: 81.390 Also contains mentions of nsfw [Rankings: #1 in #gaster (08/21/2022), #5 in #xreader (08/21/2022)]

Your favorite skeleton is back at it again... and again... agagaagaag Sans has had enough. Everyone is at the surface, holding their own jobs and lives. But... Sans can't ever let it fade from his mind. The dust. The cries. Watching the screen with Alphys as a child just rampaged in the underground. He is going to snap. He is mad. He is sad. He can never forget. Cover is NOT mine, find it online if you want ::Rights for the original concept and media 'Undertale' are all under the jurisdiction of Toby Fox. All other workings are done by me.::

What the title says.

Lots of little one-offs and side things. Enjoy! (No shipping included)

A self insert of the author of this story turns into a self aware Dreepy with all his memories intact in the Pokemon Mystery Dungeon universe but instead of becoming a hero that does dungeon crawling, he becomes a dishwasher in Spinda's Cafe where the story turns into a surreal workplace sitcom full of: fourth wall breaking, reality warping nonsense, and pure internet humor. IBADTADITPU may include:

Author's note: Brrrr this is my first ever fanfic I've ever made sksksk and for the first time, the reason for this is bc I got an idea for Gaster X reader fanfic! I guess I got inspired by other Gaster X reader fanfics or then it's (was) just an alternative version of my OC Thiara (whose a skeleton) "arrive" to the underground rather than canonically/officially being already in there, don't know! it can be both^^ But my god- I'm a bit scared tho lol since I've never done this before, I don't really want to make the characters wrong or something (might be off-character idk),,, But uh- yea, read below for the story description now,, -- (Y/N) is a skeleton who weren't trapped underground like the rest of the monsters when barrier was casted, but instead hid with her/his/their mother and her/his/their twin, but were one day found and captured.. or at least (Y/N) was. Their family wanted to rescue them, they all managed to run to the mountain where the barrier was casted, but the humans had catched up, only (Y/N) was able to get through the barrier to safety.. or rather pushed in as their rest of the family was killed. From there (Y/N) was found by queen Toriel and were taken for better healing to a certain royal scientist; W.D.Gaster! The story continues on..... -- All the Undertale characters belongs to Toby Fox!!! Reader belongs to you^^ I might give out some additional OCs or not, depends! Now babai~ Edit: I'll be using they/them pronounces for the reader-- might've forgotten to mention it before publishing anything,,,

Jessica always cursed herself for not trying harder to find Alina after she went missing. But what if she had? After finding the entrance to the Underground, she goes after her, accidentally. The king grants them a new life in the underground. There is so much to learn for them in this new world, especially the fact that they can never go back. But with the happiness they could find down there, do they really want to?

In this story Frisk a 8 year old decided to Stay trapped in The Underground with Her New Friends she made. Toriel and Asgore got back together and let Frisk live in the Kingdom as their own Child. She finally convinced Flowey to join them as well, he join in the family but never told Asgore and Toriel that he was actually Asriel. They were both left alone in the castle while all monsters went to a meeting to figure out how they will get out of the Underground without using the souls (the souls are kept safe in a room so they can be rightly lay to rest) as they were in their room a magic mirror appeared in a corner, she and Flowey walked to it and lit up and both were sucked into it. They appeared to have landed on a patch of Grass and Flowers at a near by Town, they pass out from the hard falling. They soon woke up to see and Cat and and Mouse next to them asking them if they were okay. She then met A rabbit and a Gremlin to help them, she told them where they came from and asked if they can help them get back home or someway to help her since she was a young child with a flower friend with her. But what would happen if The Mad Doctor appeared and toke both of them and became in danger?

You wanted to escape your life... you wanted to die but then a monster change everything...

This is a mha / bnha x Undertale fanfiction story. I have made my own OC that resembles me a little bit. There will be more details about him in the story. This is my first "published" story, and I totally allow criticism. There is no shipping here, except maybe Deku and Uraraka (I don't know how to spell these people's name XD). I will try and update as fast as I can, so yeah. Hope you enjoy!

Love W.D. Gaster ? Then u are ready for a lovely adventure to begin my friend ! Please read on !

With Gaster in power and the humans being hunted down by his Blaster creations will Ara ever find out what truly happened to her family? Are her siblings and Toriel really gone? With the humans powerless to stop Gaster and his onslaught to eradicate humanity will Papyrus and Sans stand up to their father or will they let the world fall to ashes? Cover Art belongs to: Deviantart: http://wezyk.deviantart.com/gallery/ Tumblr: http://wonszusart.tumblr.com/ Check out Wezyk's deviantart and Tumblr page! Epic work!

Heya, readers and future amigos! You know my Undertale semi-great fanfic, called LESSER KNOWN AUS ADVENTURE? If you don't; read that first. Now, people that stayed, hello! This book is gonna be about whatever stuff I want to write about that story, but I can't explain it in that story, or it's shipping, headcannons, and so forth. So, read this if you're interested in learning more about the LKAS crew! I hope you enjoy this! Fanart Cover By: Frogheartk

Quite a few years have passed, Frisk and her husband Asriel speak for the monsters as King and Queen. Their daughter Liv Dreemurr is a princess who is next in line to take over. But all she wants to do is hang out with her friends and live amongst the people. After a tragic evening, Liv and her best friends, (the PappyTon boys), will end up on a dangerous adventure where they will find the darkest secrets about the Skelebro's. Along the way, they will discover family, friendship, and maybe a certain emo skeleton will fall in love with the princess of the monsters.

• I reccomend you do not read this, this is my worst work yet despite it being my first. There is another story on my profile that is under development and editing. Other than that everything else here has remained untouched for over two years. DISCLAIMER: i do not own undertale nor any videos, pictures, intro, etc. And i reccomend checking out the original creators You are an ordinary teen or are you with a weird crystal appearing right next to your bed with it telling you strange things and having an encounter with a flower saying you soul is special are you really normal and is the senior year of high school really be normal with monsters starting to teach and attend school will your life really be normal? ------------------------------------------------------------------------- (This is the completely Un-Edited Version Except For The Disclaimer And Part/Chapter Date, For Those Who Would Like The Original Reading Experience) (Trust me, I've triple checked the entire thing, it sucked, lol) (Disclaimer) This is by @Shyboxes. I am archiving this with permission so people will still be able to read it. :)

[NSFW] Hello Sinners! These smutty Oneshots are from my short story "I Never Got To Tell You..." which has more fluffy romance. These are the final lemony chapters, so please enjoy 🔥💀 I may add more to this, or possibly expand upon other ships like Sansby, etc.

Unna had her role to fill as the next Tine. Almendra had her role as the next to own Grillby's bar. That left Sen with a lot of free time. He wasn't so alone as his clan might have thought, though. For as long as he could remember, he could see the grandfather that wasn't supposed to exist. But why him? The question always plagued him, but he didn't dare voice it. Not with the thought that he would look insane trying.

Probably mostly gonna be x Reader's. I'm a trash writer, so you have been warned of that. also Very Inconsistent update schedule.

Monsters have never been sent to the underground. The war that raged between monsters and humans ended in a draw, but no peace treaty leaving relations tense on both sides. The earth and cities are not in the best of shape after such a war, the weather tending to vary greatly from area to area based on residual magic left behind from the fighting. Some areas are human territory, others claimed by monsters, some simply neutral with a hope of peace and calm. Thieves and bandits are everywhere, the royal guard and police force not able to keep up with their growing numbers and largely leaving them alone at this point. Technology continues to advance, with each race constantly trying to outdo the other. Jade lives and fends for herself, currently living in an abandoned warehouse near the Hotland district, in the more desert and neutral areas between there and the human city of Külaküla. What happens though when she stumbles upon an interesting sword leading to long journey? - - - - - DISCLAIMER: I do not own Undertale or Transistor. This is a fanmade story that will have elements from both but will follow the story and head canons I accept or want to use for the sake of this particular story-line. This story will have influence from Undertale, Echotale, Transistor, and my own au Tomadachitale. You don't need to have information of them all before beginning, I'' be doing my best to explain everything at some point in the story and you can comment questions you may have about it! Plus, I'll be adding some of my own spins anyway. Thank you :3