One idea could be the Persona characters getting sucked into the JJBA universe. For example, the Phantom Thieves could end up in Morioh and have to deal with Stand users while trying to find a way back home. They might team up with Josuke and his friends to fight a common enemy that's causing chaos in both their worlds in a strange way.
Akira and Giorno would make an interesting pairing. Akira has his leadership skills and the ability to use Personas, while Giorno has his determination and powerful Stand, Gold Experience. They could learn from each other's sense of justice and different ways of achieving their goals. Akira could teach Giorno about the power of the collective, as the Phantom Thieves work as a team, and Giorno could show Akira how to be more assertive and decisive in his actions.
A crossover with One Piece might also work well. Joseph Joestar could find himself on the Grand Line, interacting with the Straw Hat Pirates. His hamon abilities could be a strange and new power for the pirates to encounter, and he could help them out in battles against the likes of the World Government or other powerful foes, while also learning about the Devil Fruits and Haki.
Maybe the Velvet Room attendants from both games somehow get their worlds mixed up. Igor from Persona 5 and Margaret from Persona 4 have to work together to set things right. This leads to the characters from both games interacting. The Phantom Thieves might learn some new combat techniques from the Investigation Team and vice versa. They could then use these new skills to face a common threat that emerges from the merging of their two realities.
Maybe there's a strange distortion that merges parts of Inaba and Tokyo. The characters from both Persona 4 and Persona 5 find themselves in this strange new place. They start to notice that the Shadows in this merged world are more powerful and have new abilities. The Investigation Team and the Phantom Thieves must figure out how to adapt their Personas and strategies to fight these new threats while also dealing with the cultural differences between their two groups.
Well, first, the fanfic should respect the lore of both SCP and JJBA. If it starts messing up the basic rules of either franchise, it can be a turn - off. The pacing is also crucial. A good crossover will have a well - paced story that doesn't rush through the interactions and developments. And finally, the world - building. How the two universes are merged should be creative and believable, like how the locations from JJBA fit into the SCP facilities or vice versa.
Well, Persona Crossover Archive Fanfiction is really interesting. It's basically fanfiction where the world of Persona meets other worlds. For example, you might see Persona characters interacting with characters from other popular games or even from different anime series. Fans write these stories to have fun and express their creativity, often coming up with unique plot twists and character relationships that add a whole new dimension to the Persona experience.
One idea could be that Kirby swallows a Persona and gains its powers. This would lead to some really interesting battles and interactions. Kirby could then use the Persona's skills in the Dream Land setting, creating a whole new dynamic.
I really like Yu Narukami from Persona 4 in the crossover. He brings his calm and collected leadership from his own game. His ability to analyze situations and keep the group together is really cool when he's interacting with the Persona 5 characters.
A great moment is when they combine their Personas' powers. Imagine the unique abilities of Persona 4's personas merging with those of Persona 5 in a battle against a common enemy. It's like a display of a whole new level of combat strategy that makes the crossover fanfiction exciting.