1 - 20 of 184 Works in Pre-Accident W. D. Gaster
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Long ago, two races ruled over Earth: Humans and Monsters. Religion and fear of differences troubled the fragile peace on which both species were living so far. A war for faith and honor soon engaged between them. Long. Endless.
Sans and Papyrus, two young skeletons brothers, sons of the Royal Scientist, lost everything in the rage of the fighting: their home, their family, their childhood. During a human attack, they suddenly found themselves delivered to bullets and bombs, all alone.
Both of them started a journey in the devastated landscapes of the end of the war to join Mont Ebott, where Monsters are preparing for a last battle. But could two kids survive by themselves in the wild and without any help?
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W. D. Gaster: the Heart, the Brain and the SOUL by WittyWind
Fandoms: Undertale (Video Game)
13 Aug 2025
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“The weight of the head of a genius is equal to its value.”
W. D. Gaster didn’t want to admit it, but he could feel it, deep inside him.
His brilliance gave a future to the Underground, a machine that could convert the heat of the Earth into energy: the CORE. The other monsters would, then, use it as electricity, and bring life to their houses and their TVs and their cars and their cell phones.
But Gaster knew more. Knew better. The CORE had so much potential, so much to offer. That kind of magic had never been used before. Gaster didn't know if he could call it “magic”, even.
He was so valuable to the Underground, but… what if that made him dangerous? What would happen if he had discovered something that shouldn’t be touched, not even by monsters or humans?
W. D. Gaster didn’t want to think about it, but he could feel it, deep inside him.
What is the value of a genius, if he’s so terrified of the weight of his own head to ever use it?
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Entry Number 10:
I should’ve expected this would happen. Much like the specimen that received the irregular solution, I feel strange. My body temperature is slowly rising, and I ache all over. Typing this entry is already difficult from the tremors in my hands. I believe that despite the increase in magic, it doesn’t affect the magic relating to bullets and damage. I’m not entirely sure what the solution is targeting, but the heat is getting unbearable. I need a cigarette…
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Before the brothers, Gaster had a different approach to breaking the barrier.What happens when you don’t perform your experiments carefully and test them carelessly on yourself
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Where is my "how to raise a babybone for dummies" book again ? [REWRITTEN] by NtBob
Fandoms: Undertale (Video Game)
11 Aug 2025
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It was cold, so cold, too cold.
You were draining, slowly, as an orange whose juice would be taken....
the warm juice, the warm and red juice. Leaking, through a dam's rift.
You felt like an empty Shell, empty of what it contained, empty, too empty.
You couldn't see anymore, couldn't hear anymore, couldn't feel anymore.
You were surrounded by emptiness. An emptiness that took everything, and nothing at once. Then, Came the light.
and you were no longer… empty.
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Or when a reader who got no memory except for Undertale and common sense, wakes up as the most mysterious skeleton of the bunch ; W.D. Gaster
It's way before Frisk fell underground, but after the Asriel/Chara incident.
(ALSO REWRITTEN FIC, I released it back in 2019, then deleted my account, all fanfics with it, decided TO WRITE THEM BACK CAUSE I LOVED THEM)
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An Unhealthy Obsession by silverstormsxx
Fandoms: Deltarune (Video Game), Undertale (Video Game)
11 Aug 2025
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Gaster and his dearest.
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Justice. by The_Universal_Maker
Fandoms: Undertale (Video Game), OFF (Game), In Stars And Time (Video Game)
03 Aug 2025
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A yellow soul prequal with a human on a mission to deliver judgment, Gaster shenanigans, and time-loop trope ripped straight out of an other game entirely, 3 routes, will any be linked to cannon in any capacity in this fanfic or are we gonna go DARKER DARKER YET DARKER.
AKA "some say yellow is the colour of justice, close but that's not the word I would use"
AKA a story I wrote in secret instead of revising for exams.
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Gaster and Grillby used to hook up a lot, but the circumstances of their lives have made it difficult to maintain anything more than the most casual long-distance relationship, even that frequently falling on the backburner in recent years. Gaster's career fair speech at New Home High School presents an unexpected opportunity to re-kindle old passions.
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Gaster wants to finish his project, but something interrupts him.
A warm feeling, so warm it burns. It doesn't make sense, skeletons don't have blood. How is this possible?He is aware that the soul should not burn the monster that possesses it. The only place he read about this was in those stories called.. "Fanfics" of Alphys mistakenly sent him.
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He chokes on the smoke, he realizes what's happening now.
How embarrassed, that ridiculous biological urge… reproduction. -
Grafted Fate by Stevethebarbarian
Fandoms: Undertale (Video Game), Deltarune (Video Game)
28 Jul 2025
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ENTRY NUMBER SEVENTEEN
*Though our prior experiments were met with failure, any unexpected result provides knowledge, and this one has proven exceptional even in that regard. Though an unfortunate mishap led to King Asgore's adopted child joining me in my fall, I will not deny the spectacular nature of our new discoveries.
*The darkness is suffocating, and yet we see. There is nothing here, and yet here we are. The only way I know to express the marvelousness of this discovery is that in this profound absence of light, an entire new world stretches forth. To say that this revelation is useful is to understate its importance to a repugnant degree.
*This place is not empty. I am told by one of its residents that their royal highness and I are bound by prophecy to save not only their world, but our world in the light above. This comes as no great surprise to me. If it were not I who were to save the kingdom of monsters, then who would?
(It's an AU where instead of getting his shit scrambled, W. D. Gaster falls into a Dark World along with Chara Dreemurr. Essentially, the plot of Deltarune takes place as a canon-divergent prequel to Undertale.)
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Welcome to DELTARUIN, a fantastical world of light and dark
Of hopes and dreams
Your choices affect the people around you, you can save lives or take them
A terrible secret lies within these dark worlds, a tale of murder and betrayal and people falling apart at the seams
You can either save them or put them out of their misery..
So..
YOU ACCEPT EVERYTHING THAT'S GOING TO HAPPEN FROM NOW ON? -
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Lyra, a devoted Undertale fan, decides to play god by rewriting the game's code to grant Asriel Dreemurr the happy ending he deserves. But when her actions pull her into the Underground itself, she finds herself trapped in the very world she tried to control.
!!!!This story contains graphic descriptions of violence, body horror, and themes of grief, trauma, suicide, and manipulation aaaand a lot more. While it may seem fluffy at first, darker themes emerge as the story progresses. There are still plenty of warm, comforting moments, but I don’t want to mislead anyone expecting a purely lighthearted tale!!!!
Also, this is very slowburn — Chara’s and the MC’s relationship progresses slower than you might expect. If you find yourself feeling frustrated with how I write Chara early on, please know it’s intentional and part of the slow build. Thanks for giving it a chance! <3
!!Currently editing. The story itself won’t change, just fixing details!!
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Sans mistakes an orange glow in the forest for a human soul...
Shenanigans ensue; pun are learned... so many puns...This is just a collection of Grillby and Sans being friends as kids and staying friends as they grow.
Grillby and Gaster do mostly talk in sign language, but I don't know sign language myself so I may include words that do not exist in sign language, but I am trying my best. Stuff said in sign language will be in italics because I find it a bit easier myself.
More tags may or may not be added. -
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"Hey, Pop?" Sans whispered, the little skeleton's eye-lights glimmering with hope and sadness all at once. Gaster's SOUL dropped before the boy could even speak, knowing that whatever he would say next was going to hurt. "Why doesn't Mum love me like you do?"
Predictably, his SOUL gave another pang, and the older skeleton breathed heavily in and out, despair clogging his ribcage and dulling his eye-lights. "She does, Sans." Slipped from him, from a natural wish to comfort his boy. "She loves you very much."
"... why don't I believe you?" Sans' expression was full of hurt, and this time, Gaster found himself lacking an answer.
Series
- Part 1 of Memorytale
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This story is my attempt at telling the story of Gaster from his own perspective -- everything that happened before his accident and everything that happened during it.
- Language:
- English
- Words:
- 1,111
- Chapters:
- 1/?
- Kudos:
- 1
- Hits:
- 22
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The Void's Waltz - Dancetale W.D. Gaster x Reader by LilouLaments
Fandoms: Undertale (Video Game)
25 Apr 2025
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DISCONTINUED!!!!
Being turned into an interactive fiction on itch.io under the same name.Everyone's heard the legends surrounding Mount Ebott.
If you go to the chasm on top of the mountain, make a wish, and throw in a seed from your favorite flower, it will come true once the flower blooms down below.
You reached out your hand, the seed clutched tightly within.
You hold your hand out above the chasm, standing much too close to the edge.
As you let of it, so did the earth beneath you, and
down
you
went.⚐︎☼︎ 💣︎⚐︎☼︎☜︎ ✌︎👍︎👍︎🕆︎☼︎✌︎❄︎☜︎☹︎✡︎📬︎📬︎📬︎
You're a dancer, your SOULmate is Wing Dingbat Gaster—AKA Bats—and you fall into the Underground to end up finding him.
WARNING, he doesn't come up for the first couple chapters!!!! -
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Doctor Gaster #8 and Alphys #8 scramble to keep up with monitoring multiple timelines. Their 7 soul-empowered Asgore is fighting a defensive war with humans. Meanwhile, during Toriel's long absence, Asgore #2 had a string of temporary lovers. But none were like Gaster.
Alternate timeline without the KingDings pairing is up on Wattpad: Prologue and Deviantart, where there will also be a post-pacifist comic: Prologue
Ask Anachronistic Asgore.
Ask Anachronistic Gaster.
Ask Anachronistic Alphys.Series
- Part 1 of Anatomical Anachronisms
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King Asgore Dreemurr had believed that his days as a father were long behind him, but when a human in labour suddenly shows up in his Castle, he finds that maybe fatherhood isn't as far out of his reach as he'd assumed. After all that he's done, can he still be a good father?
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When monster-kind has lost everything and the light of life is dimming, Gaster knows damn well he won't sit back and die without a struggle.
(It goes very, very poorly, but the benefit of hindsight is not a benefit that Gaster has.)
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After an incident in Waterfall where Sans failed to hold himself in battle, Gaster-in his fatherly concern-decides that the only way to protect his son is by teaching him how to DODGE!
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As the Royal Scientist of the Underground, Doctor Gaster was used to being given various tasks by the king of the monsters, Asgore. The first of them since they had all been sealed underground after the war was to help monsters settle down into their new home. And the second of them had been to establish a more consistent power source for monster-kind. Of course, the Steamworks had originally been developed to do the same thing, but the power it provided wasn’t nearly enough to cover all of it.
Over the course of several years, the Royal Scientist had designed the CORE and had it built, a much larger version of the Steamworks that managed to successfully run power through the entire underground. And it wasn’t even like his position had only been granted to him after being sealed underground, he’d been working for the king and queen for what must’ve been at least a century. Pros of being a monster who’s yet to have children, he supposed.
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A short story about W.D. Gaster prior to falling into his creation.
Series
- Part 1 of Undertale/Deltarune Fanfics