One idea could be that Broly somehow ends up in the world of Black Lagoon. He might initially be seen as a huge threat by the Lagoon Company. But as the story progresses, they realize his power can be useful against their common enemies. For example, when facing powerful crime syndicates or military forces that are too much for them to handle alone.
Well, Broly is extremely powerful and has a short temper. The characters in Black Lagoon are tough but not on Broly's level. So, there would be a lot of tension at first. For instance, Revy from Black Lagoon is used to being in control in a fight, but Broly would completely overpower her. This would create a power struggle within the group.
In a crossover with One Piece, Luffy could be an ally. Luffy is known for his open - mindedness and ability to befriend almost anyone. He would see Broly's power and might try to get him to join his crew or at least fight alongside him against common enemies. They could have some really fun interactions, like Luffy trying to make Broly laugh or share his love for food with him.
One idea could be that Naruto and his team are sent on a mission to the world of Black Lagoon. They team up with Rock to take on a powerful crime syndicate that is after a powerful jutsu Naruto has. Another could be that Revy gets transported to the Naruto universe and has to deal with the shinobi world's politics while also teaching some of the younger ninjas her combat skills.
In a crossover with the Naruto universe, Naruto himself could be an ally. Naruto has a way of seeing the good in people, and he might try to reach out to Broly and convince him to use his power for good. His ability to befriend and understand others could be key.
I think Hinata and Balalaika would make for a really interesting pairing in a Naruto Black Lagoon crossover fanfiction. Hinata is shy and gentle, while Balalaika is a powerful and intimidating crime boss. Their interactions could be really fascinating as Hinata tries to understand Balalaika's world and Balalaika might be a bit bemused by Hinata's innocence. Also, Kakashi and Dutch could be a great pair. Kakashi's calm and strategic mind would work well with Dutch's leadership skills in the Lagoon Company.
Trunks would also be a great choice. Trunks is from the future and has a different set of skills and experiences. He could introduce Broly to some new technology or fighting techniques from his own timeline. And together, they could face threats that neither could handle alone, like a time - traveling villain.
Vegeta could also be an interesting choice. Vegeta has his own pride and issues with power, much like Broly. In a crossover fanfiction, they could start off as rivals, constantly trying to outdo each other in terms of strength. But as the story progresses, they might find common ground and have to work together against a common enemy. This would be a great way to explore both of their characters in more depth.
A third common theme could be the exploration of different universes. The fanfictions might delve into how the Dragon Ball universe, where Broly comes from, and the RWBY universe coexist or affect each other. This can include things like different laws of physics, magic systems, and cultural differences between the two universes.
There is a fanfiction called 'Garcia and the Lost Treasure'. In this story, Garcia embarks on a quest for a long - lost treasure. It's full of action and adventure, and it shows Garcia's skills and determination in a whole new light.