One idea could be creating an OC who is a powerful mage from a long - lost clan. They could join the main characters on their journey and use their unique magic to help in battles and solve problems. For example, they might have the ability to control time briefly, which could be crucial in a tough fight against a powerful daemon.
The unique perspectives. A male oc can bring a fresh view to the FFXV world. For example, he might have different values or abilities compared to the existing characters, which can lead to new and exciting storylines.
A possible plot for Harry Potter FFXV fanfiction is that the Death Eaters somehow make a pact with the empire in FFXV. This forces the heroes from both universes to join forces. Harry and Noctis could learn from each other's combat styles and magical abilities. The wizards could teach the FFXV characters about spells like Apparition, while the FFXV characters could show the wizards how to use their unique weapons and summons in combat.
Maybe there could be a story where the Keyblade wielders from Kingdom Hearts visit the world of FFXV to learn about their unique form of magic. They could then exchange knowledge, like how Noctis' warp strikes could be adapted into a new Keyblade ability.
Character team - ups are also great. Like having Prompto and Yang team up. Prompto's sharpshooting skills combined with Yang's brawler style would make for an exciting duo. They could learn from each other in combat and in terms of personality, Prompto's more light - hearted nature could balance Yang's sometimes hot - headedness.
One idea could be creating an OC who has a unique power related to time manipulation. They could be from a different dimension and end up in the Avengers' world. Another idea is an OC who is a master of ancient magic and teams up with Doctor Strange within the Avengers group. Maybe an OC that is a super - intelligent android created by a villain but has a change of heart and joins the Avengers.
You could create an OC for your Persona OC fanfiction who is an artist. This artist OC could use their art as a way to understand and even manipulate the Metaverse. For example, they might draw scenes from the Metaverse that give clues about upcoming events or hidden locations. Their art could also be a form of therapy for other characters who are struggling with their dual lives in the real world and the Metaverse.
Perhaps an OC who is a half - human, half - beast creature. This OC could struggle with acceptance in both the human and beast - kin societies. They end up meeting the main characters during their adventures and learn to embrace their unique identity with the help of the group, while also adding their own combat skills, which are a blend of human strategy and beast - like strength, to the team.
One idea could be to explore the Riddler's origin story from the perspective of your original character (OC). Maybe your OC is a detective trying to solve the mystery of the Riddler's first crime spree. Another idea is to have your OC be a sidekick of the Riddler, either willingly or by being forced into it. They could then have a complex relationship where the OC tries to influence the Riddler's actions for better or worse.
One idea could be an OC who is a brilliant scientist in the Fallout world. They could be working on a secret project to reverse the effects of radiation. Another idea is an OC who is a wandering trader, having all kinds of adventures while traveling from one settlement to another, facing raiders and mutants along the way. And a third idea could be an OC that is part of a new faction trying to bring peace and order to the wasteland.
You could also create an OC human who discovers a hidden talent for communicating with trolls through music. In the fanfiction, this character could use their musical ability to bridge the gap between the two worlds, maybe even creating a new form of harmony between trolls and humans that was previously unthinkable.