1 - 20 of 163 Works in Human-Monster War (Undertale)
Navigation
Listing Works
-
Tags
Summary
A long time ago in a undisclosed AU....
Dr. W. D. Gaster was always heralded as a Kind SOULed scientific genius... creator of such breakthroughs as the CORE, Dimensional Boxes, and much much more... helping Monsterkind find new HOPE after being suddenly trapped under a Mountain...
So why does Sans fear him as the devil incarnate... a Monster among Monsters that made his early years a nightmare... a complete polar opposite of how everyone else perceived him...
...almost like they were two different Monsters...
.........what if... what if... they WERE two different Monsters?
................what if... there was TWO Monsters named W. D. Gaster?
Series
- Part 4 of a SERIES of unaVOIDable events
- Part 1 of unaVOIDable destinies
-
Tags
Summary
"Traumatized people chronically feel unsafe inside their bodies: the past is alive in the form of gnawing interior discomfort."
-The Body Keeps The Score, Bessel van der Kolk
Dr. W.D. Gaster is not a happy man...but he had been, once. Perhaps he could be again.
...and he can't stop thinking about you. Can't make himself stop thinking about you.
A story in which love, quite literally, saves the world.
(Now in Arc 2)
-
Tags
Summary
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?
-
I Will Take Your SOUL and Break Your Heart by i_never_ate_raindrop_cake_but_i_want_to
Fandoms: Undertale (Video Game)
22 Aug 2025
Tags
Summary
A story that narrates the adventure of a young woman and her new Human — but also Monster! — friends. She wants to be able to give everyone the Happy Ending they all so crave.
They need help in ending this Sorry Tale before it is too late.
ᯓ★
He asked you why you betrayed him. His breathing was ragged, and his hair did not have the same pleasant odor of coconut oil and wheat that you had grown to love. It was musty, reminding yourself what kind of monster you had in front of you.
Not a Monster, but a monster.
The meaning of his name didn't carry his personality anymore.
"... Ironic, is it not? Since I am not the one who is holding a dusty knife right now."
Series
- Part 1 of Petrichor
-
Tags
Summary
The Goddess of the Sun, supportive of Humans.
The Goddess of the Moon, supportive of Monsters.
Two sisters in a battle between two species, two opposites against one another. What will happen when the Day tries to force itself over the Night?
-
Tags
Summary
Gaster wants answers to his questions, regardless of the universe he’s in. (Even if he inadvertently caused those questions himself, intentionally or unintentionally…)
He’s been alone as long as he remembers and the only thing that could be a “clue” to his identity and hidden memories is a metal plate drilled into his right hand.
Or Gaster tries to find answers but everything goes worse for him.
Handplates! AU (reversal of roles)
-
Santuarytale by Harmony_of_Endless (RynoxPolux27)
Fandoms: Undertale (Video Game), Assassin's Creed - All Media Types, Multi-Fandom
17 Aug 2025
Tags
Summary
Santuario
(Del lat.) Sanctuarium.1. Un lugar fundamental que ofrece seguridad, protección o refugio contra el peligro, la persecución, el dolor o las influencias dañinas.
2. La idea central es la de un espacio donde se está a salvo y, a menudo, se encuentra paz o consuelo. Además, proporciona asilo y cuidado a aquellos que lo necesitan.
3. Lugar sagrado dedicado a una deidad, objeto religioso o figura venerada.
4. Un espacio donde se puede encontrar calma, serenidad y aislamiento del estrés, el ruido o las perturbaciones del mundo exterior.
Series
- Part 2 of Libercordia
- Part 2 of Senderos fragmentados de Harmony
-
Tags
Summary
Grillby and Asgore never were friends, but they tolerated each other for the sake of monster kind and the war. But after the death of King Aether Dreemurr, a violent collision course for disaster was inevitable between a grieving new King, Asgore Dreeemurr and an emotionally detached General Grillby.
- Language:
- English
- Words:
- 2,217
- Chapters:
- 1/1
- Kudos:
- 8
- Hits:
- 47
-
Tags
Summary
[Honestly..
After everything you've been through you didn't expect to find yourself here, in the middle of a fight between two men you recognized too much to be normal, with your unconscious husband in your arms having a near death grip on both newborns while you could at least stand without feeling your legs numb.
You lost hope of being able to hide when both turned to look at you and your dear still sleep in your arms, whom you quickly hid from sight with your cloak, covering him as much as you could.
"Fuck.."]
Or; After years of being responsible for making the impossible possible in a crumbling world, your people receives an unexpected but not less welcome peace. You don't plan on freeing your claws from this chance.
-
Reborn | Tân sinh. by meomoon
Fandoms: Anh Trai Vượt Ngàn Chông Gai | Call Me By Fire (Vietnam TV)
13 May 2025
Tags
Summary
Chọn lọc tự nhiên là quá trình phân hóa khả năng sống sót và mức thành đạt sinh sản của các kiểu gen khác nhau trong quần thể, từ đó dẫn đến đào thải các kiểu hình kém thích nghi, đồng thời tăng cường khả năng sống sót của các dạng thích nghi, tạo cơ hội cho các kiểu gen thích nghi này đóng góp vào vốn gen của quần thể ở thế hệ sau.
Tiến hóa là quá trình biến đổi các đặc điểm di truyền của một quần thể sinh vật qua các thế hệ liên tiếp, dẫn đến sự đa dạng hóa các sinh vật và hình thành các loài mới. Tiến hóa là một quá trình liên tục, không ngừng nghỉ và không có mục đích. Tiến hóa là một quá trình phổ biến xảy ra ở tất cả các loài sinh vật.
-
Tags
Summary
Sans did not remember his previous name, only that he had been human. Rebirth in Undertale was novel, but he adapted, until he realized that the universe he was in was not the original one.
Unfortunately, it was too late when the machine took him to another universe, into a room full of skeletons.
——————————————————————————————
Sans no recordaba su nombre anterior, solo haber sido un humano. Renacer en Undertale fue una novedad, pero se adaptó, hasta que cayó en cuenta de que el universo en el que estaba no era el original.Lamentablemente, ya era tarde cuando la máquina lo llevo a otro universo en un cuarto lleno de esqueletos.
Nota: Sé que suena como tragedia, pero en realidad es una historia bastante esponjosa de curación, o al menos eso intento. Nuestro protagonista tiene mucho trauma y lo va a sanar en una mansión llena de esqueletos incómodos
-
Tags
Summary
A year has passed since Frisk has freed the Underground, and their desire to learn more about their friends hasn't stopped there. After asking Asgore about the lack of skeleton monsters and realizing that the mystery behind Sans and Papyrus goes much further than they thought, they set out to find answers. What started as one question quickly spirals, and they and their friends stumble into something bigger than they ever could have imagined.
Summary to be redone as the story goes on.
-
Hazbin Hotel "Trailer" by AmandaGrace148
Fandoms: Undertale (Video Game), Deltarune (Video Game)
12 Apr 2025
Tags
Summary
Once upon a time, Monsters were rumored by be sealed in Underground, behind a magical barrier. Many humans believe it to be just old fairytale, meant to keep kids safe and not wander off...
But one human was determined to find out : Chara, an unlucky child, but a dreamer at heart, was the first human of Underground, coming hand-in-hand with Asriel, prince of Monsterkind. Wishing to unite their worlds, the two children combined their souls, which only lead to their premature damnetion.
Chara, broken by their misery, broke down and lost the will to dream... but Asriel thrived, with power of human determination, he learned to control time, helping Monsterkind to free themselves from their prison...
But upon reaching the surface, humans showed their heartless nature. That every year, army of humans would attack monsters, to prevent them and their kind leaving their prison of time in Underground...
And yet, Asriel's hope remained, as his dream was passed down to the precious child, Chara was blessed with. Kris Dreemurr, the royal child of Monsterkind.
Series
- Part 5 of Trailers
- Language:
- English
- Words:
- 1,524
- Chapters:
- 1/1
- Hits:
- 106
-
Tags
Summary
An imagining of the story before, slightly during, and maybe after the war. Relations between humans and monsters are beginning to sour, and now Gaster must navigate life in his new, unfamiliar home. Unfortunately for him, himself and everything he knows could end up changed forever...
-
Tags
Summary
The child awakes underground to traverse the world of monsters and find a pathway out as they learn more of the residents and a way to maybe save more then just their self. But as they do, another friend appears to aide them, as an ancient corruption revives along with the child to reclaim their vengeance. How will the child and their friend deal with such a demon... or demons...?
Enjoy a twist on the tale.
Series
- Part 1 of Origins (Undertale)
-
Tags
Summary
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.)
-
Memories in the Void: Enter The Skeleton District by Kuma_In_Pink
Fandoms: Undertale (Video Game)
29 Mar 2025
Tags
Summary
A year and four months. That's how long it's been since the Final Reset. Everyone has been living their best lives on the Surface. Sans, for one, couldn't be happier. The silly old woman he used to pun with is now his girlfriend. He's an awesome Dunkle and Not Dad Guy to Frisk, Chara and Asriel. Papyrus is finally living his best life and everyone is moving forward.
There's just one little caveat. One teensy little flaw in an otherwise happy ending.
Sans is dying. On the evening of his 27th birthday, no less.
Fortunately, a certain skeleton outside of space and time knows what to do.
"If you want to save Sans, all of you must be willing to pay the mental and emotional cost."
In order to bring Sans back to life, those closest to him will have to view his important memories. Along the way, the group will unearth all the skeletons in his closet...
...As well as their own.
LAST UPDATED: 03/29/2025!
Artwork by Nightmare Estudios!
Note: To anyone who has read this before the name change, the story is still the same. I've just updated the title. :)
Series
- Part 1 of Bondtale
-
Tags
Summary
Deimos, the God of Fear, revealed in mortal's fear and misery on Earth. Monsters wreaked havoc, allowing Deimos to grow powerful overtime. It was so chaotic that Ananta, the God of Creation, took notice. It seems that Deimos has forgotten his role as a God.
Series
- Part 1 of FEAR Inc.
- Language:
- English
- Words:
- 8,024
- Chapters:
- 3/?
- Hits:
- 9
-
Tags
Summary
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.
-
A short story about W.D. Gaster prior to falling into his creation.
Series
- Part 1 of Undertale/Deltarune Fanfics
-
Tags
Summary
Unfinished (occasionally dubiously-canon) snippets, deleted scenes, alt povs, pre- and post-canon junk, and some AUs within the universe of Gossip Merchant.
Series
- Part 3 of Gossip Merchant