Leorio and Yang would be quite a combination. Leorio's medical knowledge could be useful when Yang gets injured in battle. And Yang's brash and energetic personality could pull Leorio out of his more serious and studious mode. They could also have some funny exchanges about money and values, as Leorio is often concerned about finances while Yang is more about the thrill of the fight.
I think Killua and Ziva would make a great pair. Killua has his assassin background and lightning - fast reflexes, and Ziva is a former Mossad agent with her own set of combat and investigative skills. They could have some great action scenes together and also share their experiences of growing up in a world of danger and secrecy.
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.
I think Blake would also be a great focus. Her stealth and agility would translate well in the Monster Hunter world. Plus, her cat - like Faunus traits could give her an edge in certain situations, like tracking or sneaking up on monsters.
Maybe the monsters from the Monster Hunter world start appearing in Remnant, the RWBY world. The RWBY teams then have to adapt their fighting styles to take on these new and powerful foes. They might study Monster Hunter strategies to gain an edge.
There's a 'hunter hunter crossover fanfiction' that involves a crossover with 'Naruto'. In this story, the ninjas from Naruto and the hunters from Hunter Hunter form an alliance to fight a common enemy. The fanfic does a great job of exploring how the two very different worlds would work together, like how the nen abilities would compare to chakra techniques.
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.
The Doom Slayer and Ruby would be an interesting pairing. Ruby is young and full of energy and hope, while the Doom Slayer is a silent, stoic force of destruction against evil. Their interactions could be really cool, like Ruby trying to understand the Doom Slayer's lack of words but seeing his determination and being inspired by it. And the Doom Slayer might see Ruby's potential and unwavering spirit in the face of danger as something similar to his own.
Ruby and Noel would be a great pairing. Ruby is young, energetic, and has a strong sense of justice. Noel is also a very determined and kind - hearted character. They could bond over their shared values and also learn from each other's combat styles. Ruby could show Noel some of her acrobatic moves with Crescent Rose, while Noel could teach Ruby some of the finer points of her swordsmanship.
Ruby and Frisk would be a really interesting pairing. Ruby is full of energy and determination, and Frisk has that unwavering kindness. They could learn a lot from each other, especially in terms of how they approach difficult situations and make decisions.
I think Ruby and the Dragonborn would be an interesting pairing. Ruby is young and full of energy, and the Dragonborn has a lot of power and experience. Ruby could learn a lot about different forms of combat from the Dragonborn, and the Dragonborn could be inspired by Ruby's positive attitude.