If Deku had a quirk in fanfiction, it would likely impact his character development. He might have become more powerful quicker or taken on different enemies. The story could become much more action-packed or focus on different themes.
It could make for a really exciting and unique story. Deku's growth and challenges would be measured in a more structured way, adding a new layer of excitement to his journey.
This was a very common scene in the entertainment industry where a male star would perform well on stage and be serious, but would often display all kinds of idiotic behavior offstage. This kind of persona could not only increase the popularity of the celebrity but also attract more fans. For example, in the entertainment industry, some male stars would play a serious leader on stage, but in private, they would be very humorous and funny. There were also some male stars who would take this persona to the extreme, such as being very formal in public but often posting silly content on social media. No matter what kind of persona it was, it could make the male stars in the entertainment industry more popular and attract more people's love.
In 'Persona 4 Visual Novel', the gay persona might represent the diversity of the game's character creation and the exploration of different sexual orientations within the game's fictional world. It could add more depth to the relationships and storylines.
Perhaps the fanfiction focuses on the cultural clash between the two groups. The Persona 4 characters are from a small town, while the Persona 5 crew is from the big city. Their different ways of handling things and their unique Personas could lead to some interesting interactions. For example, Yu and Joker might have different leadership styles that they have to reconcile in order to succeed against the shadows.
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.
In 'deku meets future deku fanfiction', perhaps the future Deku warns the present one about upcoming threats. He could tell him about villains he'll face in the future and how to defeat them. This would give the present Deku an edge in his battles and also in his growth as a hero.
One idea could be the characters from Persona 4 and Persona 5 swapping their worlds. So the Phantom Thieves end up in Inaba and have to deal with the Midnight Channel mystery. And the Investigation Team finds themselves in Tokyo and gets involved in the Metaverse. It would be really cool to see how they interact with the different environments and characters.