A crossover with One Piece would also be cool. Luffy and Gon could form an alliance on the Grand Line. Gon could be intrigued by Luffy's Devil Fruit powers and they could go on adventures together, facing the challenges of both the One Piece world and the Hunter x Hunter world.
Another possibility is a crossover with Fullmetal Alchemist. Edward and Gon could meet and share their quests. Edward's knowledge of alchemy and Gon's nen abilities could create some interesting interactions. For example, they might try to find a way to combine their powers to solve a common problem.
One idea could be a crossover with Naruto. Gon and Naruto could team up and learn from each other's unique ninja and hunter skills. They might compete in a friendly way to see who's stronger in different aspects like physical strength or strategy.
In a 'Hunter x Hunter crossover RWBY fanfiction', it could be that the Nen abilities in Hunter x Hunter are seen as a form of magic in the RWBY world. Some of the RWBY characters are fascinated by this new power source and want to learn about it. So, they make a deal with the Hunters to exchange knowledge about their respective powers. This leads to some really interesting training sessions and battles where they combine Nen and Semblance powers.
One idea could be that Naruto and Gon meet during a strange interdimensional rift. They initially misunderstand each other but soon realize they have a common goal of protecting their friends and worlds. Another could be that the Akatsuki and the Phantom Troupe somehow cross paths and form an uneasy alliance to achieve their own ends, which involves stealing powerful artifacts from both Naruto's world and the Hunter x Hunter world. And a third idea might be that Naruto and Killua swap places for a short time, experiencing the different power systems and cultures of each other's worlds.
One idea could be exploring the next generation of Hunters. Maybe Gon and Killua have kids who inherit their unique abilities and embark on their own adventures. They could face new threats and discover hidden secrets in the Hunter world.
One idea could be a crossover where Kagome's spiritual powers are needed in the Hunter x Hunter world to deal with some powerful Nen - using villains. Maybe she teams up with Gon and Killua to fight a common enemy that has a connection to both her world and theirs.
One idea could be exploring a new type of nen ability that a character discovers. For example, a nen ability that allows the user to manipulate time in a very limited way, like slowing down time for a few seconds during a battle. This could add a whole new dimension to the combat in the fanfiction.
One idea could be exploring an uncharted area of the Dark Continent that has unique and deadly creatures not yet seen in the main series. Another could be a story about a group of hunters from different families teaming up specifically for a Dark Continent expedition, facing internal conflicts as well as external threats.
A fanfiction could focus on a character from Harry Potter who is a secret Hunter x Hunter fan. They could be constantly comparing the two worlds in their mind. Like how the Sorting Hat in Harry Potter is similar to the way Hunters are selected in Hunter x Hunter. Or how the Forbidden Forest in Harry Potter has some similarities to the Dark Continent in Hunter x Hunter.
One idea could be exploring the backstories of the members of Genei Ryodan in more detail. For example, how they joined the group and what their lives were like before.
A fanfiction could focus on an alternate universe where Meruem doesn't die and he and Komugi explore different parts of the Hunter x Hunter world together. They could encounter new species and cultures, all while Meruem continues to learn from Komugi's innocence and wisdom.
A plot could revolve around Menchi's past. Maybe she has a hidden connection to a powerful group or a long - lost family member. This could lead to a story of self - discovery as she uncovers secrets from her past while still maintaining her role as a hunter and a food expert. She might have to face old enemies or make difficult choices regarding her new - found knowledge.