What are some interesting plot ideas in 'undertale meets underfell fanfiction'?

One interesting plotline could be the clash of different character personalities. For example, the more aggressive characters from Underfell interacting with the kinder ones from Undertale. They might start off not getting along but gradually learn from each other.

One idea could be that the characters from Undertale find themselves in the Deltarune world and have to adapt to its different rules and characters. For example, Sans could meet Ralsei and they could have a humorous exchange about the nature of their respective universes.

Maybe in the fanfiction, the Dark Fountains from Deltarune start appearing in the Undertale world. This causes chaos as the monsters in Undertale don't understand what these strange fountains are. Frisk, along with the Deltarune trio, has to figure out how to stop the fountains from spreading darkness. They could learn from each other's powers and strategies. For example, Frisk could teach Kris about determination in a more in - depth way, and Kris could show Frisk how to navigate the strange new areas created by the Dark Fountains.

Well, a cool plot for 'Undertale meets Underswap fanfiction' might involve a character exchange program of sorts. Papyrus from Undertale goes to Underswap and tries to teach his Underswap counterpart how to be more confident in his cooking skills. At the same time, the Underswap Sans could come to the normal Undertale world and introduce new ways of having fun to the rather serious Sans there. This could lead to a series of comical and heartwarming interactions between the characters from both universes.

One interesting plot idea could be that characters from Undertale end up in the Overtale universe and have to adapt to its different rules and power systems. For example, Sans might find it strange that magic works in a more complex way in Overtale. Another could be a character from Overtale getting lost in the Undertale world and having to deal with the moral choices that the Undertale characters face, like whether to kill or spare enemies.

In such a fanfiction, there could be a lot of conflict. Underfell Sans is from a more hostile AU than Undertale. He might initially be distrustful when meeting the characters from Undertale. For example, he could misunderstand their kindness as weakness or a trick.

Well, in 'mlp meets undertale fanfiction', there could be crossovers of characters. Picture Fluttershy befriending a shy monster in Undertale. Her kind nature could help the monster come out of its shell. Also, the magic system in MLP could blend with the combat or determination - based mechanics in Undertale. It might create new ways for the characters to overcome challenges. For instance, Twilight Sparkle's magic could be used to solve some of the puzzles in the Underground in a different way than the normal Undertale characters would.

Sans is often a very popular character in these fanfictions. In both Undertale and Underfell, he has a distinct personality. In Underfell, his more edgy and somewhat darker side can create interesting interactions when combined with the regular Undertale Sans.

Frisk would be a likely candidate. Since Frisk is the main character in Undertale and has a very adaptable personality. They could approach Underfell Sans with an open mind and try to understand him.

Frisk is also quite popular. Their role as the main character in Undertale and how they would interact with the darker or different versions of characters in Underfell and the swapped - up world of Underswap makes for great fanfiction material. They can be the mediator or the catalyst for change in the crossover story.