There's also 'A Blazing Bond'. In this fanfic, the OC has a unique power that ties into the existing powers in the Fire Force world. It delves deep into the relationships between the OC and the canon characters, exploring how they grow and change together. It's really engaging as it combines action and character - driven plotlines.
First, know the Fire Force universe well. Understand the rules about Infernals, the different Companies, and the powers of the characters. Then, create an OC with a unique backstory and personality that can fit into this world. For example, if your OC has a fire - related power, make it different from what already exists in the show.
Well, you could create an OC fanfiction where the OC is a scientist who discovers a new way to combat Infernals that doesn't involve burning them. This OC might be initially rejected by the Fire Force but then proves their method's worth. Also, an OC with a special connection to the Adolla Burst could be interesting. Maybe they can communicate with the spirits of the Infernals or have visions related to the Adolla realm, which would lead to new adventures and revelations within the Fire Force world.
First, you need to create your OC. Decide on their appearance, personality, and backstory. For example, if your OC is a tough - as - nails firefighter, think about what made them that way. Then, think about how they fit into the Fire Force world. Are they joining a new company? Next, come up with a basic plot. It could be as simple as your OC trying to solve a mystery within the Fire Force. Just start writing and let the story unfold.
Another way is through their relationships. In the case of a Tamaki x OC fanfiction, their interactions with Tamaki are crucial. If the OC is initially shy around Tamaki due to her confident and outgoing nature, but gradually opens up, it shows character growth. Also, their relationships with other members of the Fire Force can contribute. Maybe they have a rivalry with one member that forces them to improve their skills, which in turn affects their overall character development.