1 - 20 of 651 Works in Martlet (Undertale Yellow - Master Sword)
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Noelle Becomes Brave by IllegalMeerkat
Fandoms: Deltarune (Video Game), Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
20 Oct 2025
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Summary
The world is on a collision course with the end of everything.
Noelle Holiday is attacked in Hometown while walking home, and after returning home a week later, she knows that something is wrong. Her mother isn't acting right, and there's something out in the woods around her house.
With all of her friends and family holding secrets, the Roaring looming overhead, and the knowledge that the world rests on her shoulders, Noelle forgoes her mental health to make a better tomorrow. She'll get stronger.
Whether her friends let her is another story.
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Deltarune: Red & Yellow by youraveragefanficreader1710
Fandoms: Deltarune (Video Game), Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
19 Oct 2025
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Summary
I don't have any vague summary.
But essentially, it's Deltarune with Undertale Red and Yellow sprinkled in.
Kris' SOUL is comprised of three souls, Frisk as the Red SOUL, Chara as the Black SOUL, and finally Clover as the Yellow SOUL.
This AU will also feature UT Yellow characters, integrated into Deltarune. Will they have significance? We'll just have to wait and see...
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UDY on the Surface by CommanderBullet
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game), Deltarune (Video Game)
19 Oct 2025
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It's been a few years since Monsters returned to the Surface and lots of things have changed... Accompany your favorite characters from Undertale, Undertale Yellow and Deltarune as they try to manage their everyday responsibilities and go through a few wacky adventures while at it in this slice-of-life crossover AU.
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Someone powerful is tired of the bad endings. Time to take fate into their own hands.
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Three years ago, a brother left his sister to search a mountain that no human has ever returned from.
Three years later, the sister, desperate for answers, follows her brother's footsteps.
The two meet again, but the result is likely the most hectic two weeks of their lives. And one of them has already lived an eventful life.
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Just an ordinary trip to the underground.
Oh yeah! And Frisk has the ghosts of all of the past humans in their head! What could possibly go wrong!
Frisk and the humans adventure around the underground, and help to tie loose ends and help each other with their problems.
Series
- Part 1 of Undertale: Sevenfold
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Deliverance From Self-Destruction by Agent_ArcticFox
Fandoms: Undertale Yellow (Master Sword Video Game)
18 Oct 2025
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Summary
Alexander Koskinen is not a perfect man, but he’s lived his life to what he believes is the best he could. But after falling into the underground, that belief is shattered, and the guilt that has built up over the years has come crashing down, a weight he can no longer bear alone like he has for so long. Now it’s up to Chujin Ketsukane, patriarch of the Ketsukane household, to help pick up the pieces of this lost soul’s life, lest he be consumed by the past that’s been haunting him for all these years.
Series
- Part 1 of UTY: Absolution
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Diving for Justice, Freedom and Managed Democracy by Dangeresque_On_Ice
Fandoms: Undertale (Video Game), Undertale Yellow (Video Game), Helldivers (Video Games)
17 Oct 2025
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Summary
The Monsters were dead.
They must have been, the Federation of Super Earth had said so; annihilated during the Great Galactic War along with all the other threats to Managed Democracy. So Clover was understandably confused when he set out to find the five missing Cadets only to discover a whole society of Monsters sealed underground.
What’s more, these Monsters were nothing like the tyrannical, Freedom-hating killers history had portrayed them as.
Things just weren't adding up. But why? It’s not like Super Earth would have lied, right?
Now with a TV Tropes page: https://tvtropes.org/pmwiki/pmwiki.php/Fanfic/DivingForJusticeFreedomAndManagedDemocracy
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Howdy, Hometown! by MoruMoru
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
17 Oct 2025
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Summary
A year or so has past since Monsterkind has been freed.
A little place called Hometown sits at the base of mt Ebott, a town consisting of monsters who go about their normal, daily routine. This normality is swiftly upended, as a young human teen - one who the monsters have never seen before - suddenly appears in Hometown.
Spurred at this exciting, new prospect, the bluebird monster Martlet - local carpenter and craftsmonster - excitedly takes the new human across a tour of Hometown, determined to show all the wonderous things the town has to offer.
But one can't help but wonder... is there more to this new human's visit?
Series
- Part 2 of MoruMoru's UTY collection
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Early Awakening by 3Pleatv
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
17 Oct 2025
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Summary
Well.
This was new.
Chara was not accustomed to being see-through. After all, being corporeal had been their natural state for most, if not all of their life.
Did that make this non-life or undeath?
They were doubly unaccustomed to seeing another human in the Underground.
Were they dressed as a cowboy????
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Basically: Undertale Yellow if NarraChara was still prevalent! What will change? What will stay the same? And WHY is this flower following them around so intently?! -
Justice Evolved by The_Spar1an
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game), Deltarune (Video Game), Undertale Red & Yellow (Video Game)
17 Oct 2025
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Clover remembers.
After spending quite some time dead, He finds himself with memories he'd rather not have.
Memories that tell him who he truly is.
Memories that haunt him.
edit: lowkey put me on the stuff I was on when I wrote this summary.
Anyway, basically Clover remembers resets, especially genocides. So he basically remembers how to use his powers from previous runs as well, and then la tee doo dee dum, and bam. Justice Evolved.
If you're curious enough to have questions, maybe read the fic. It'll boost my ego. (please)
(edit) Disclaimer: if you want to read for cocoapowder, cocoapowder chapters will be released at a later date. As of this edit, the relationship between Clover and Chara has yet to be explored.
------------------------------This work will contain Original characters for the sake of worldbuilding, and I fully intend to make some of them play major roles in the story.
This is an alternate universe to Undertale Red and Yellow.
This work will be from Clover's POV. (written in first person, not second person, aka "I" instead of "You") -
Parental Union by DemonicPrince23
Fandoms: The Owl House (Cartoon), 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), Murder Drones (Web Series), Phineas and Ferb, Undertale (Video Game), Deltarune (Video Game), Five Nights at Freddy's, Harry Potter - J. K. Rowling, Bendy and the Ink Machine, Star Wars - All Media Types, Undertale Yellow (Video Game), & More - Fandom
16 Oct 2025
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Summary
To my sister, assuming she finds this: PLEASE DON'T KILL ME! I saw the ship listed in the list of ships and was intrigued. I'm sorry.
To anyone confused: She and I know what I'm talking about. If she doesn't... Well, I'll survive for sure, unless I do something dumb and show her it. If she does... Well, I'll need to pray.
Credit for the idea goes to a Discord friend of mine, Voltage, who isn't a fanfic writer, but came up with the idea.
Credit for each individual fandom goes to their creators. I am none of them.
Credit for the story itself, however, is mine.
I kept forgetting, but since I remember right now, allow me to announce that...
This work has a TV Tropes page! -
Open the Light by SomeoneNotReallyNoteworthy
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
16 Oct 2025
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Happiness was rare for Clover in their life, something he now never expected with his sacrifice.
Kanako thought her happiness was over with her grave mistake.
Yet here they were, meeting each-other outside the bounds of reality. The puzzle, however, is far greater than anyone realized. Not everything will stay forgotten.
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Quartet Rune by Kittany_the_Fox
Fandoms: Deltarune (Video Game), Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
16 Oct 2025
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Summary
In Deltarune's world, Chara and Frisk both run away from their 'homes' the same night. Unbeknownst from each other, they still arrive at the same little town.
Wounded, Chara has to be taken in. With nowhere else to go, Frisk is sent with them to stay with Toriel for the time being.
Kris is not too happy about this, especially since soon, everything will be set into motion. Two human kids, one acting out and the other curious to a concerning extent, will only make it harder for them. At least it can't get even more complicated.
...why is there a third one and why are they here ?? To... 'find the missing kid' ?
WHY ARE THEY STAYING OVER TOO.
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Regrowth (one step at a time) by Pillow_Fort
Fandoms: Undertale Yellow (Master Sword Video Game), Undertale (Video Game)
15 Oct 2025
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Or, Clover is revived after the true pacifist ending. Follow their journey as they reunite with old friends, discover new things, and help solve the interpersonal drama of the underground! (most of which is just them getting adopted)
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A controller's dismissal by Sirsonan
Fandoms: Undertale Yellow (Master Sword Video Game)
15 Oct 2025
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Flowey wasn't going to RESET Clover this time. Even he has his limits before his patience runs thin. Although time RESETs anyways. Flowey figures out who used HIS powers and scares them into leaving. This run faces the consequences of that action.
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Dragon Ball Yellow by zakalekk
Fandoms: Dragon Ball, Undertale Yellow (Master Sword Video Game), Undertale (Video Game)
14 Oct 2025
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What if Son Goku managed to win with Jiren alone, and then made a selfish wish? What would happen in the underground, if Son Goku appeared there shortly after Clover's sacrifice?
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Rowen cares for a sick Martlet.
- Language:
- English
- Words:
- 291
- Chapters:
- 1/1
- Kudos:
- 1
- Hits:
- 16
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Double Jeopardy by Oryans
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
14 Oct 2025
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Summary
Clover climbed Mt. Ebott to find to the children who'd gone missing there. Against all odds, their brother climbs up after them.
Series
- Part 1 of Against Better Judgement
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New Hometown by NullVol
Fandoms: Undertale (Video Game), Deltarune (Video Game), Undertale Yellow (Video Game)
14 Oct 2025
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Summary
School is about to begin for the children of Monster Town, making life all the more hectic for them. That is only reinforced by the sudden appearance of a new human who feels they have no control over their own life.
Tags are subject to change. May go on hiatus a few times as I imagine this one to be on the larger side.
Series
- Part 3 of To Resurface