What are some interesting ideas for Undertale crossover fanfiction?

One idea could be that the ponies from MLP end up in the Underground world of Undertale. Maybe Twilight Sparkle could use her magic to interact with the magical elements in Undertale, like the SOULs. Another idea is to have Sans and Papyrus meet Fluttershy. Papyrus would be all excited to show off his 'coolness' while Fluttershy might be a bit shy at first but then they could become friends over their love for cooking (Papyrus loves making spaghetti).

One idea could be that the characters from Undertale find themselves in the FNAF pizzeria. Sans could use his shortcuts to avoid the animatronics' attacks. Another idea is that the FNAF animatronics end up in the Underground. Freddy might befriend Toriel, and she could try to 'fix' them. Maybe Papyrus would be terrified of the animatronics at first but then try to befriend them with his overly friendly nature.

The concept of power dynamics is also fascinating. In a 'Undertale Gaster Crossover Fanfiction', Gaster's power, which is not fully understood in the original game, could be compared or combined with the powers of other characters. This might result in epic battles or the need for characters to cooperate in ways they never had to before in their respective stories.

One idea could be that the characters from Undertale end up in the FNAF world. For example, Frisk could be trying to find a way to escape the haunted animatronics while also befriending some of them in a similar way they befriend monsters in Undertale. Sans could use his shortcuts to outwit the animatronics' movements. Another idea is to have the FNAF animatronics transported to the Underground. They might be seen as strange new 'monsters' and the Underground residents would have to figure out how to deal with them.

One idea could be that Naruto characters end up in the Underground world of Undertale. For example, Naruto with his determination could be seen as similar to the determination trait in Undertale. He might interact with Sans and Papyrus. Naruto could use his shadow clones to confuse the enemies in the Underground. Another idea is that the ninjutsu in Naruto could be combined with the magic system in Undertale. Maybe Sasuke's Sharingan could have an interesting interaction with the soul mechanics in Undertale.

One idea could be that the characters from Undertale find themselves in the world of Deltarune. For example, Frisk could end up in the Dark World and have to figure out how to get back home while interacting with the Deltarune characters. They might team up with Kris to fight against new threats that are a combination of both universes' villains.

Character interactions are also great. Imagine Frisk from undertale meeting Pikachu. Their personalities are so different. Frisk is this kind and empathetic character, while Pikachu is energetic and curious. Their meeting could lead to all sorts of comical or heart - warming situations. Maybe Frisk tries to communicate with Pikachu in the undertale way, and Pikachu responds in its own pokemon - like way.

One idea could be that Percy ends up in the Underground world of Undertale. He might use his water powers in unique ways against the monsters there. For example, he could create water shields to block attacks from the more aggressive monsters like Undertale's Flowey. Another idea is that Sans could somehow end up in the Camp Half - Blood from Percy Jackson. Sans' laid - back attitude would be a contrast to the usually intense and heroic demigods at the camp.

One idea could be Sans from Undertale ending up in the Marvel universe. He could use his shortcuts and bone attacks to fight alongside the Avengers against a common enemy like Thanos. His laid - back attitude would contrast with the more serious heroes in Marvel.

One idea could be that the Turtles end up in the Underground world of Undertale. They might have to navigate through the various regions, like Snowdin or Hotland, using their ninja skills. For example, they could use their stealth to avoid some of the more dangerous monsters. Another plot could involve the characters from Undertale being brought to the Turtles' New York. They would then have to deal with the Foot Clan and other threats in this new, strange environment.