One popular pairing could be Blossom from Powerpuff Girls Z and Ruby from RWBY. Their leadership qualities might draw them together, and they could be seen as a powerful duo in combat situations, with Blossom's intelligence and Ruby's speed and scythe - wielding skills complementing each other.
Buttercup from Powerpuff Girls Z and Yang from RWBY might also be a popular pairing. They both have a bit of a tough - girl attitude. Yang's strength and Buttercup's superhuman strength and combativeness could make for an exciting relationship in fanfiction, whether it's a friendship or something more.
One popular pairing could be Ruby and Noble 6. Ruby's innocence and determination combined with Noble 6's stoic and experienced nature can create an interesting dynamic. Their relationship could be based on mutual respect for each other's combat abilities and a shared goal of protecting the innocent.
In some fanfictions, there could be a plot where the powers of the Powerpuff Girls Z combine in a new way when they are in the RWBY world. For example, their chemical X - like powers could interact with the Dust in RWBY to create unique abilities. This could lead to them training the RWBY characters in this new form of power usage.
In RWBY and Team Fortress 2 fanfiction, Ruby and the Engineer could be a popular pairing. Ruby's fascination with weapons and the Engineer's talent for building and inventing could lead to some great stories. Weiss and the Medic might also be a popular choice. Weiss' need for perfection and the Medic's scientific approach could be an interesting combination. And Blake and the Sniper could be a pairing that fans like. Blake's stealthy nature and the Sniper's long - range precision could create some exciting scenarios.
Sasuke and Weiss might also be a popular pairing. Sasuke's brooding nature could contrast with Weiss's more refined and sometimes cold exterior. Their interactions could involve Sasuke teaching Weiss some of his ninja skills, and Weiss helping Sasuke understand the more sophisticated aspects of RWBY's world.
In RWBY Kamen Rider fanfiction, Pyrrha Nikos and Kamen Rider OOO are a popular pairing. Pyrrha's selfless and noble personality goes well with OOO's ability to combine different forms. Additionally, Nora Valkyrie and Kamen Rider Fourze are also favored. Nora's exuberant and strong - willed nature along with Fourze's space - themed powers make for some fun and unique storylines.
Another one could be Weiss and Zelda. Weiss, with her noble upbringing, might find common ground with Zelda, who is also a princess. They could bond over their leadership skills and the need to protect their respective worlds. In fanfiction, they might team up to face a great threat that endangers both Remnant and Hyrule.
A pairing that has gained popularity is Rukia and Pyrrha. Rukia's cool - headedness and Pyrrha's kind - hearted and strong - willed nature work together well. Their friendship or potential romantic relationship can be a central point in many 'bleach rwby crossover fanfiction'. Additionally, some fans also like the idea of Byakuya and Glynda. Their no - nonsense attitudes and leadership qualities can be an interesting combination to explore.
Obviously, Blossom, Bubbles, and Buttercup are the most popular. They are the main characters after all. But villains like Mojo Jojo are also often included as they provide great conflict. Also, the Professor who created the Powerpuff Girls can be an important character in fanfiction, especially if it involves the origin story or some kind of scientific experiment gone wrong.
Professor Utonium is a popular character to include. He is the creator of the Powerpuff Girls and his relationship with them can be explored in different ways in fanfiction. Maybe he creates a new experiment that has unexpected consequences for the girls. Another popular character could be the Rowdyruff Boys as they can create interesting rivalries and storylines with the Powerpuff Girls.
The Professor is another character that often appears in fanfiction. Writers might explore his backstory more, or they could create scenarios where the Professor has to make difficult decisions regarding the girls' powers or safety. His role as the girls' creator gives a lot of room for interesting plot developments.