An engaging Persona and RWBY fanfic can be created by exploring the themes of both. Persona often deals with self - discovery and facing one's inner demons, while RWBY is about teamwork and fighting for a better world. You could create a story where the characters from both universes have to work together to overcome a common threat that embodies both these themes. For instance, a powerful Grimm that can only be defeated if the RWBY characters understand their inner selves like the Persona characters do. In terms of writing, make sure to give each character their own voice. Don't make the RWBY characters sound like Persona characters and vice versa. This will make the fanfic more believable and engaging.
One idea could be that the RWBY characters enter the Metaverse from Persona. They might have to face their Shadows, which could be related to their Grimm - fighting fears or personal insecurities. For example, Ruby could face a Shadow that represents her fear of not being able to protect everyone.
It could be a blend. RWBY characters have their weapon - based combat and Semblances. Persona characters have their Personas with various elemental attacks. Maybe the Personas could enhance the RWBY characters' weapons or Semblances. For instance, a Persona with fire abilities could make Yang's punches even hotter and more powerful.
A great plot could be that a new threat emerges that has the power to erase the memories of people in both Persona 4 and Persona 5's worlds. The characters from both games must work together to find the source of this threat. The Phantom Thieves could use their infiltration skills, while the Investigation Team could use their detective - like skills to gather clues. As they progress, they discover that the root of the problem lies in an ancient evil that was once sealed away but has now been awakened due to some modern - day events.
One possible plot could be that the characters from RWBY end up in the Persona universe and have to learn how to use Personas to fight the Shadows. For example, Ruby could discover her Persona is related to her speed and scythe skills, and she uses it to quickly dispatch enemies. The team would also have to deal with the social aspects of the Persona world, like building relationships to strengthen their Personas.
The characters would likely be initially cautious. For example, Yu from Persona 4 might be a bit reserved when meeting Joker from Persona 5, but as they learn about each other's goals, they would start to trust. Yosuke might be excited to see the more high - tech Metaverse compared to the TV World, and he could bond with Ryuji over their shared love for adventure. Chie would probably challenge Ann to a fight at first, thinking she's just a pretty face, but then realize Ann's strength.
Maybe the Persona users' powers start to malfunction in the RWBY world due to the different nature of the place. So they have to figure out how to control their powers again while also helping the RWBY characters in their battles. The RWBY characters could be intrigued by the Persona powers and try to learn from them.
Another idea is a crossover with a superhero universe. Minato could find himself in a world full of superheroes and villains. He'd have to figure out how his Persona powers work in this new context. Maybe he teams up with some heroes to fight a common enemy, like an evil entity that threatens both his world and the superhero world.
Ruby and Joker could be a great pairing. Ruby's enthusiasm and determination combined with Joker's cool - headed leadership skills would make for an interesting dynamic. They could learn from each other's combat styles and ways of thinking.
Ruby and Yu Narukami. Ruby is young and full of energy, always eager to fight for what's right. Yu is a calm and collected leader. Their different personalities would make for an interesting dynamic. Ruby could learn from Yu's more methodical approach to problem - solving, while Yu could be inspired by Ruby's unwavering determination.