Tsunenaga Tamaki can be an interesting character to focus on. He is the director of Deadman Wonderland and is full of secrets. A fanfiction could explore his motives, his past, and how he came to be in charge of such a cruel and corrupt place. You could also write about his interactions with other characters from a different perspective.
Shiro is also a fan - favorite. Her mysterious past and her connection to Ganta make her a great character to write about. You could write a story that reveals more about her origin, or a story where she has to make difficult choices that put her relationship with Ganta at risk.
The Mad Hatter is also popular. You could write about his tea parties in more detail, or create a story where he loses his 'madness' and has to find it again. Maybe Alice has to help him in this journey of self - discovery.
The Cheshire Cat is a very popular choice. It's that mysterious character that can disappear and reappear at will, and its sly and sometimes helpful nature makes it really interesting to write about. Writers can explore its motives and what it really knows about Wonderland.
In Peter Pan fanfiction, Peter himself is often a central focus. His eternal youth and adventurous spirit make him an appealing character. Also, Tinker Bell is popular. In Alice in Wonderland fanfiction, Alice is the obvious choice. Her journey through Wonderland is full of mystery. The Cheshire Cat is also a favorite as it is so enigmatic.
Shiro is also a very interesting character. Her relationship with Ganta is complex and mysterious. She has her own secrets and powers that add a lot of depth to the story. Her loyalty and the enigma surrounding her make her stand out.
The White Rabbit is often just seen as the one who leads Alice into Wonderland, but he could be so much more in fanfiction. He could be a time - traveler, for example, and his hurry is because he's always on a tight schedule to different eras. The Tweedle brothers are also underrated. They could be the key to unlocking some ancient secrets of Wonderland. In a fanfiction, they could lead Alice on an adventure full of riddles and puzzles that reveal the true nature of Wonderland. And the Caterpillar is quite an interesting character to focus on. It could be a wise sage who holds the knowledge of the entire Wonderland universe.
I think a great Senji x Toto fanfic could involve their adventures within Deadman Wonderland. Maybe they team up to face a new and powerful enemy in the prison. Senji's tough - guy attitude and Toto's unique abilities could make for an interesting dynamic. Writers might also delve into their backstories and how they influence their relationship in the fanfic.
There are many great fanfictions out there about Senji and Toto. Some might focus on their relationship development within the harsh environment of Deadman Wonderland. Maybe they explore how they first met and gradually came to trust each other.
One idea could be a crossover with 'Attack on Titan'. The Deadman Wonderland characters could find themselves in the world of Titans and have to use their unique abilities to survive. For example, Ganta's ability to shoot his blood bullets might be useful against the Titans. Another idea is a crossover with 'Fullmetal Alchemist'. The alchemical world could interact with the prison - like setting of Deadman Wonderland, and perhaps there could be a search for a way to break the curse in Deadman Wonderland using alchemy.
One idea could be exploring the backstories of the minor characters in Deadman Wonderland. For example, you could write about how a particular inmate ended up in the prison. Another could be a what - if scenario, like what if Ganta had different powers. Maybe he could control water instead of his blood bullets.
One idea could be a crossover where Naruto characters are trapped in Deadman Wonderland. For example, Naruto could use his shadow clones to deal with the various challenges and enemies in the prison. Another idea is to explore how the powers in Deadman Wonderland would be used by Naruto characters. Maybe Sasuke could master some of the blood powers in a unique way. And a third idea could be a story where the main Naruto characters have to form alliances with the Deadman Wonderland inmates to escape the prison together.