The protagonist is surely one of the most interesting characters. As an extra reborn, they have a unique perspective on the world. They might have memories of their previous life which makes their actions and decisions different from the regular extras in the story. Also, any character who helps or hinders the protagonist's journey can be interesting. For example, a mentor - like figure who guides the protagonist in this new world, or an antagonist who tries to keep the protagonist in the 'extra' status.
In 'Reborn as an Extra Novel', I find the side characters with hidden motives quite interesting. They seem unassuming at first but as the story unfolds, their true intentions are revealed. Another interesting character could be the one who has a special power or ability that is not common in the story's world. This character's power can either be a source of envy or inspiration for the protagonist. And of course, the character who is the most different from the social norms of the fictional world is also very interesting.
The antagonist is often very interesting. In Assassin Reborn, the antagonist might be someone from the assassin's past who has also changed or someone who is threatened by the assassin's new - found power. Their motives and methods of trying to stop the protagonist can be full of twists and turns, making them a character to watch out for.
The slime protagonist is quite interesting. His transformation from a human to a slime and his unique growth process make him stand out.
The titular greatest demon lord is definitely one of the most interesting. His journey from being a powerful and feared figure to being reborn and having to adapt is captivating.
Perhaps the people who interact with the reborn demon lord are interesting too. They might be ordinary folks who are unaware of his past. Their reactions to him and how they influence his new life could be very engaging. For example, a kind - hearted neighbor who befriends him without knowing his true origin.
Octavia is one of the most interesting characters. She grows from a girl living in the shadows to a strong and independent fighter. And Jaha, his journey of faith and how it affects his actions and decisions in the post - apocalyptic world makes him a very engaging character.
The 'extra man' is surely a main character. Additionally, there might be characters representing the society he is in. For instance, there could be a group of people who conform to the norms of the community. Their reactions and interactions with the 'extra man' would be important. There may also be a character who is in a similar situation as the 'extra man' but has chosen a different path, which could create an interesting dynamic and comparison within the story.
One of the main themes could be self - discovery. The protagonist, being reborn as an extra, has to figure out their new place in the world. Another theme might be the idea of changing one's fate. Since they are in a new life, they can try to avoid the mistakes or misfortunes of their previous existence. Also, it could touch on the concept of relationships, as they interact with other characters in this new life and form new bonds.
Harry Potter himself is often a popular reborn character. Writers like to explore what would happen if he had a second chance at life and could change things. It allows for a lot of creative interpretations of his character growth and how he would handle the challenges differently.
Sheldon himself is often a popular choice. Writers like to explore what would happen if he was reborn with some changes, like being more socially adept from the start. It adds a new dimension to his character.
Mary Jane is an interesting character. She has a complex relationship with Peter. On one hand, she loves him, but on the other hand, she has to deal with his secret life as Spiderman. Also, Aunt May is interesting. She is a kind of moral support for Peter, and her innocence about his double life adds an interesting layer to the story.