For a more out - of - the - box choice, Sonic the Hedgehog could be a unique character for a Ryuki crossover. His speed could be an interesting element to play with in the context of a fight with the Ryuki riders. And from a different anime, Lelouch from Code Geass. His strategic mind could lead to some really complex and interesting storylines when involved in a Ryuki crossover.
Well, from the Kamen Rider universe itself, characters from Kamen Rider Blade could be great for a crossover. Their different powers and personalities would create interesting interactions with the Ryuki characters. Another suitable character could be Kiva. His vampire - like nature and unique fighting style would add a new flavor to the Ryuki crossover.
Ryuki is often very popular. He's the main character in the original series, so he's a natural focus in fanfiction. His journey and his growth as a rider make him an interesting character to write about.
One idea could be a crossover with other Kamen Rider series. For example, Ryuki characters interacting with those from Kamen Rider Decade. They could team up to fight a common enemy that has the ability to travel between different Rider worlds. Another idea is a crossover with a popular anime. Maybe Ryuki riders in the world of Naruto, where they have to adapt their fighting styles to the ninja world.
Ryuki himself is a popular choice. His complex backstory and his quest for justice in his own universe make him an interesting character to explore in a crossover. He has a strong sense of right and wrong and his fighting style is cool.
Kamen Rider Decade is often a popular choice. His ability to transform into other Riders makes him a natural for crossovers. He can bring in elements from different series and connect various storylines together.
Characters from Kamen Rider Decade are also frequently included. Decade has the ability to travel between different Kamen Rider worlds, so it makes sense for him to be in a 555 crossover. His presence can introduce new story elements and bring different Kamen Rider series together in a single fanfiction.
Well, other Kamen Riders are very likely. For instance, Kamen Rider Chalice, as he has a connection with Blade in the original series. Their interactions in a crossover could explore more of their relationship and how they work together against new threats.
Definitely Kamen Rider Decade is a very popular character to include. His ability to transform into various Kamen Riders gives endless possibilities for crossovers. And then there's Kamen Rider Zi - O, as the time - traveling Rider, he can bring a whole new dimension to the kamen rider w crossover fanfiction. Additionally, Akiko Narumi from the Kamen Rider W series herself is often included, as she can add a touch of normal - human - in - a - Rider - world perspective to the story.
Ruby Rose is often a popular choice. Her energetic and determined personality makes her a great candidate to interact with the Kamen Rider characters. She could be curious about their transformation abilities and might try to incorporate some of their techniques into her own combat style.
A more complex idea could involve the Mirror World from Ryuki. In the fanfiction, the RWBY characters could be accidentally pulled into the Mirror World. There, they meet the Riders from Ryuki and have to figure out a way to escape. Along the way, they learn about the rules and dangers of the Mirror World, and also discover some secrets about their own powers.
Tsukuyomi is also quite popular. She has her own set of abilities and a connection to Zi - O. In crossovers, she can interact with other female characters from different Kamen Rider series in unique ways. Also, Kamen Rider Decade is often included. Since he has the ability to travel through different Rider worlds, he can bring a lot of chaos and new story opportunities to a Zi - O crossover fanfiction.