Lenina Huxley can be an interesting character to center a fanfiction around. As a citizen of the future society, she has different views from Spartan. A fanfiction could explore how she changes her views through her interactions with him.
Simon Phoenix is also a great choice. His evil and chaotic nature provides a lot of material for fanfiction. You could write about his backstory, what made him become such a dangerous criminal.
John Spartan is a very popular character to focus on. He has a complex personality, being a tough cop from the past. You can explore his struggles to adapt to the new society while still holding onto his old values.
Mike Baxter is a great character to focus on. His leadership skills and family - man values can be explored further in a fanfiction. For example, how he would adapt those values in a post - apocalyptic world. Another could be Vanessa Baxter, exploring her intelligence and how she might contribute to the survival of the group.
In the Demolition Man story, the central character is a tough police officer who was frozen in time. Another important character is the antagonist, a criminal who creates problems in the future world. There are also other characters in the future society who play roles in either helping or hindering the cop as he tries to adapt and save the day.
I don't know specifically since I haven't read the novel. But there could be a demolition expert as a main character.
Naruto himself is always a popular choice. His journey from an outcast to a hero is full of material for fanfiction. Sasuke is also very popular. His brooding nature and his search for power make for interesting stories. Kakashi is another one. His mysterious past and his cool ninja skills are great to write about.
Miles Morales is definitely a popular choice. He's the main character in the movie, and his journey of becoming Spider - Man is full of potential for further exploration. His relationship with his family, especially his father, and how he balances his normal life with his superhero duties can be delved into deeper in fanfiction.
Obviously, Spider - Man himself is a very popular character to focus on. His relatable character, with his high - school problems and superhero duties, makes for great fanfiction material.
Saitama is definitely a popular choice. His overpowered nature provides a lot of interesting angles for fanfiction. For example, you could write about a time when his nonchalant attitude gets him into trouble with the other S - Class heroes who don't understand his strength.
You could also create a fanfiction where the frozen criminals start to form an alliance within the prison. They come up with a plan to escape and take over the new 'utopian' society, and the story could be about how the hero stops them.
Hannibal is often a popular focus. His leadership skills and strategic mind make for great storylines. Writers can explore his past military experiences in more detail or create scenarios where he has to outwit an even smarter adversary.
One of the most popular characters to focus on is likely the main protagonist. His leadership skills and complex personality make for great storytelling. Another could be the tech - savvy character. Their ability to get the team out of tough situations using technology is always exciting to write about.