Little Nightmares and Undertale Crossover Fanfiction: What Are Some Interesting Plot Ideas?

One idea could be exploring the backstory of the Thin Man. Maybe he was once a normal child in the world of Little Nightmares but something happened to turn him into that terrifying figure.

One idea could be a crossover with Hollow Knight. The protagonist of Little Nightmares could find themselves in the Hallownest, facing the strange and often menacing bugs there. The dark and eerie atmosphere of both worlds would blend well.

Well, another plot could involve Sans and Papyrus coming to the RWBY world. Papyrus might be fascinated by the Grimm and try to befriend them, while Sans could use his powers to help the RWBY team in their battles against Salem. He could also share his knowledge of timelines with Ozpin.

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.

Well, it could be that there is a glitch in the multiverse that causes a fusion of the two worlds. So we have characters like Frisk interacting with Freddy Fazbear. Frisk might try to show the animatronics a different way of living, more like the pacifist way in Undertale. And in the process, they all have to deal with the threats that exist in both worlds, like the purple guy from FNAF and the more malevolent monsters from Undertale.

A possible plot could involve the souls in Undertale having some connection to the spirits that are rumored to be in the FNAF animatronics. The main character from Undertale, perhaps Frisk, could enter the FNAF world and try to free the trapped souls. In return, the animatronics could help Frisk in the Undertale world against some powerful foes.

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.

An Undertale and My Hero Academia crossover is also a great concept. The heroes and villains in MHA could find themselves in the Underground. Characters like All Might could have interesting interactions with Asgore. And the idea of quirks in MHA and the unique abilities of the Undertale characters could be a really cool aspect to explore, like how Bakugo's explosive quirk might compare to Sans' bone attacks.

One idea could be that Harry Potter accidentally finds a portal to the Undertale universe while exploring the Forbidden Forest. He has to learn the rules of this new world, like dealing with the concept of LOVE and EXP. Maybe he teams up with Sans to fight off Voldemort who has also found his way into the Undertale world and is causing chaos by using dark magic on the monsters.

One idea could be that Dipper and Mabel end up in the Undertale universe. They might meet Sans and Papyrus. Dipper could be intrigued by the magic system in Undertale and try to study it, while Mabel would probably befriend the friendly monsters right away. Maybe they get involved in the conflict between humans and monsters in the Undertale world and use their Gravity Falls knowledge to find a new solution.