In some fanfictions, they form alliances. The RWBY team might see the potential of Kamen Rider Build's powers in their fight against the Grimm. They could train together, with the Kamen Riders teaching the RWBY characters about their unique fighting styles and the RWBY characters sharing their knowledge of Dust and Aura. This kind of cross - training can lead to really interesting character development and new combat techniques.
Often, they start off as strangers. For example, the Kamen Rider Build characters might accidentally end up in the RWBY world. They'd be confused at first, but then start to interact. Maybe the RWBY characters would be cautious at first, like Weiss might be skeptical of these new 'visitors' until she sees their combat abilities.
Ruby, with her eagerness to grow as a fighter, would study the Kamen Rider's fighting styles and abilities in the fanfiction. She'd be inspired to incorporate some of those moves into her own combat repertoire. Weiss, being the strategic one, would look at how Kamen Rider approaches different situations in the fanfiction and apply those concepts to her own planning. Blake would see the Kamen Rider's fight against darkness as similar to her own fight against the Grimm. She might draw strength from the Kamen Rider's unwavering determination. Yang, always up for a challenge, would be excited by the physical feats that Kamen Rider performs in the fanfiction and strive to match that level of power.
The characters would likely start off with some level of mistrust. For instance, the Avengers might be suspicious of Build's powers and his motives at first. However, as they face threats together, they would start to respect each other. Iron Man and Build could bond over their love for technology and inventing new gadgets. Captain America might be initially skeptical but would come to admire Build's courage in battle.
One interesting fanfic could be where the Kamen Riders from Build end up in the RWBY universe and team up with the huntsmen and huntresses to fight a common enemy. For example, they might face off against a Grimm that has been enhanced by some Evolt - like technology.
In a more complex way, they could be brought together by a common enemy. For instance, an evil force that wants to steal the power of both chakra and the magic in the Kamen Rider world. They would then need to communicate and strategize to fight this enemy. This would involve Naruto explaining his ninja world concepts like jutsu and clans, while Kamen Rider Wizard shares his knowledge about the Phantoms and magic rings.
One great 'Kamen Rider Build' fanfiction story could be about an alternate universe where Build teams up with other Kamen Riders from different series to fight a common super - powerful enemy. This kind of crossover fanfic can be really exciting as it combines different powers and personalities.
Another popular character could be Blake Belladonna. Her stealthy nature and her ability to use her shadow clones could interact well with the kamen rider powers. In fanfiction, she might team up with a kamen rider to take on enemies that are difficult to defeat using her normal RWBY abilities alone. For example, a kamen rider's ability to detect hidden threats could complement Blake's stealth skills.
One idea could be that the Avengers are transported to the world of Kamen Rider Build. They team up with Build to fight a common enemy that has the power to disrupt both universes. For example, a villain who can manipulate matter like Build's powers but on a much larger scale, threatening Earth in the Avengers' world and Build's city in his world.
Ruby would be all in. She has an open - minded and adventurous spirit, so she'd be quickly drawn into the unique storylines of the Kamen Rider fanfiction. It would be like opening a new door to a whole different fictional universe for her.
The worlds could merge through a mysterious portal. This portal could be created by some powerful jutsu in Naruto's world that goes wrong or by an experiment in Build's world. Once the worlds start to merge, the characters would be in for a shock. The ninjas in Naruto's world would see the advanced technology of Build's world, and the people in Build's world would be amazed by the use of chakra.
Naruto's ability to sense chakra could be used to detect hidden enemies in the Kamen Rider Drive world. In that world, there might be villains who can cloak themselves using technology. But Naruto's chakra - sensing ability would cut through that and allow him and Drive to be one step ahead in battles. And Drive could use his gadgets to then counter - attack these enemies.