The butterfly effect is known as "a property of chaotic systems by which small changes in initial conditions can lead to large-scale and unpredictable variation in the future state of the system." The smallest of changes make the largest of impacts. So… What if when Angel and Frisk fell… they fell into different locations? Squeal "One World, Two Souls", and "One World, Many Souls".

Sans is tired of the resets. He decides to do something about it to change things for the better. Everything just sort of goes downhill from there. Created By: AveragePotato

After falling into the Underground, Frisk is found by a young Monster and taken home, where they find friendship and family, and make a new life for themself in the Kingdom of Monsters. But despite the happiness, something lingers in the back of their mind, and soon, they find a way to repay the kindness which they have been shown.

For Monsterkind, the Surface represented freedom. For Frisk, it's a return to some uncomfortable realities. It all began with a simple wish. When that wish faded, Frisk tried to move on. Except, 'moving on' was not so simple. Emerging from the Underground had put them in a worldwide spotlight. From an unknown child, they had become an icon of great value.

Sans tries to use a new strategy to save his world from the being that is trying to wipe out all of monsterkind. This backfires tremendously when a human from the real world (that doesn't even know about Undertale) gets transported into his universe. Will this result in friendship, a game of cat and mouse…or the absolute?

Daniel es un chico de 20 años con un gran apego a su cariñosa madre, pero ella contrae una peligrosa enfermedad que le costaría su vida, para poder curarla necesita un ingrediente muy especial. Flores Doradas, Daniel debe partir al Monte Ebott pero caería en un agujero que lo lleva a conocer un nuevo mundo y a una bella mujer cabra, del cual el se enamora perdidamente.

After a tragic accident, a young boy named Vance wakes up in the world of Undertale his favorite game. Reincarnated as a human with magic powers, he finds himself living alongside the monsters he once knew only from his screen. With familiar faces and unexpected adventures around every corner, Vance explores the Underground.OC Harem Fic include characters from Deltarune/ UT Yellow

Amplification. The power to amplify... anything. including itself. ... let's see how this goes. not sure on the rating so I'll just leave it on the minimum until I write something to raise it up. kind of fast paced. I hate stories that just drag on and on.

Short stories set in the VOXISTALE universe.

¿Alguna vez pensaste qué sería de este mundo si las leyendas resultaran ser ciertas? ¿Si las historias transmitidas de generación en generación sobre criaturas desconocidas fueran reales y no simples relatos ficticios? Sin duda, a cualquiera le daría intriga indagar en la veracidad de este asunto. Más aun si vives cerca de uno de los lugares más famosos del mundo.

RESETING after another True Pacifist run through the Underground, Frisk puts themselves into a situation they found too difficult to finish. After meeting with Sans, Frisk decides to RESET one more time and regain their happy ending. But they find themselves unable to continue; instead, they stay behind to SPARE the Monsters they called friends the burden of knowing them.

The power of Determination is a strength that humans have in spades. It's what let you journey through the Underground, it's what kept you going in spite of it all. It's what drove you to try and SAVE Asriel... by any and all means. But what happens when that Determination falters? What happens when Determination rots under the weight of what you've done?

This is a sequel to my old story, Integritale, which you will find in my profile. I don't know if this could be considered an AU to the Undertale Universe, since I did add a lot of stuff, but still tried to adhere to the canon as much as possible. In any case, please, enjoy! Any feedback is welcome!

It's only thanks to you that I could change from a sadistic ogre to what I am now. I feel alive for the first time. I can't thank you enough, but I can write down my story. - This story follows Frisk and Chara from a genocide run to a truly happy ending!

[Horrortale AU] After their fight against Omega Flowey, Frisk left the Underground to get help and save their friends. Unfortunately, humans are not as comprehensive as monterkind and they didn't believe them. How to change their mind ? In the Underground, the situation is getting worse. Toriel and Undyne are fighting for the throne, and chaos is taking place in the Kingdom.

Asriel is miraculously revived and is living happily with Frisk, Toriel, Asgore, and the other monsters. But Frisk has a secret, and Chara is tormenting them for it. 3 years later, they go back to Ebott and help Chara regain their compassion after having an empty soul for so long. A year after, Frisk is still the tiniest bit resentful towards Chara cuz..y'know. Fem Frisk Male Chara

In the wake of the human's devastation, Papyrus was made king, and his brother Sans was made to suffer the consequences of his own inaction. Papyrus has a lot to live up to, and as time goes on he is forced to face the past and make a grave decision for his people's future. (Speculative story about the King Papyrus neutral ending).

Just because your father is "Renowned Scientist Dr. W.D. Gaster" doesn't mean everything in life goes according to plan. Corbel H. Gaster knows this entirely too well. If trying to balance school, friends, and a life-altering disease wasn't hard enough, Corbel must also face the pressure of living up to his father's legacy. AU story for "The CORE of the Matter" CONTAINS SPOILERS!

A Multiverse Phenomenon drags Nightmare to a place that should be unreachable. Yet it changes the course of this Multiverse irrevocably.

"Long ago, two races ruled over Earth: Humans and Monsters." One race feared for their strong souls, the other for their magic, and the mages caught between them feared for both. All silently knew that war would be inevitable. The only thing that mattered was surviving it. One crimson mage understands that well, and is determined to keep herself and those she cares for alive.

"El jugador" ha muerto... Y ahora todos quieren JUGAR. En la peligrosa Ebott City, radica una constante inconformidad por habitar monstruos y humanos en un mismo lugar., desatándose conflictos delictivos que atentan con la vida de los habitantes. Sin importarle las advertencias de su madre, Frisk decide ir a la ciudad y tener su florería junto con su compañero y mejor amigo Flowey

In a reality where existence is a jigsaw puzzle of shattered worlds, a certain doctor has survived the collapse of his own universe and now embarks on a mission to build something new. Join one W.D Gaster utilizing the Observer, a creation of his own design, and navigate a realm where perfection is a mirage and every piece of a broken world holds the key to a bold new beginning.

Deltarune, but with Muffet. It's very short because I want to go to bed. Also it wouldn't let me pick Deltarune as a category. Sorry.

Gaster lost count of the days since he first entered the Void, but since that day, he had watched and analyzed each and every timeline there was. Just a few more resets, he calculated, and the timelines would start to mix. Worse, they would start to destroy each other. He had to make things right, stop the resets, and to do that, he had to leave the Void. UPDATE 2024: NEW EPILOGUE!

This takes place after the genocide run, where Chara will be fighting with Frisk. Also Chara and Frisk are both girls in my AU and As the future awaits, what choice will Frisk takes? RESET? SAVE? will they fall in the same situation again? or maybe things will be different this time. . . (also the cover is made by me!)