A fanfic could focus on Rize teaching Kaneki how to fully embrace his ghoul side. She could show him how to use his powers more effectively and how to hunt without attracting too much attention. In return, Kaneki could teach Rize about human emotions and values, which she might have lost touch with over the years of being a ghoul. This exchange could lead to a deep bond between them.
One possible fanfic could be about how Rize and Kaneki's relationship evolves in a world where they manage to overcome their differences. Maybe they start to understand each other's pain and loneliness, which were deeply rooted in their ghoul and half - ghoul existences respectively.
A fanfic could focus on the backstory of the Kamishiro brothers. Explore their childhood, how they discovered their powers, and what led them to become who they are. Maybe there was a tragic event in their past that shaped their personalities and made them so close to each other.
First, know the characters well. Study their personalities, motives, and relationships in the original work. This will help you write them in a way that is consistent. For example, if one brother is more impulsive, show that in your fanfic.
Well, you can try searching on fanfic platforms like Archive of Our Own. Look for tags related to 'kaneki x kaneki' and exclude any tags that might indicate lemon or adult content. There might be some great platonic or friendship - centered fanfics about these two characters.
A common theme is the exploration of their dual identities. Given that they are the same character in different states, fanfics might delve into how they interact with this shared yet distinct self - awareness. Another theme could be self - discovery, as they come to terms with who they are both individually and in relation to each other.
Unfortunately, Kaneki did die in the manga. This event was a turning point that brought about many changes in the storyline and the dynamics among the characters.