Sasuke is always a popular choice. His complex backstory and his journey of redemption can be explored further in fanfics. Writers can delve into his internal struggles, like his feelings towards his clan and his relationship with Naruto in more depth.
Kakashi is also a great character for 'naruto chronicles fanfic'. There's a lot that can be written about his past, his experiences during the Third Great Ninja War, and how he became the teacher to Team 7. Fanfics could show his growth as a ninja and as a person outside of what was shown in the original series.
Shikadai is quite popular. His laid - back yet intelligent nature makes for an interesting character to write about. Inojin and Cho - Cho are also good choices. You can focus on their growth as ninja, their relationships with their parents' generation, and how they contribute to the new ninja world in the 'naruto gaiden fanfic'.
Suigetsu Hozuki is a well - known character. He has a laid - back yet determined personality. A fanfic could focus on his past before joining Sasuke's team, perhaps his training and how he came to master his water - based abilities.
David is often a popular choice. His connection to the dragons and his growth throughout the original story gives a lot of material for fanfiction. Writers can explore his further adventures and how he continues to develop his relationship with the dragons.
The main dragon keeper is often a popular choice. Their relationship with the dragons and their growth throughout the story can be really interesting to write about.
Sasuke is a very popular choice. His complex backstory and brooding personality offer a lot of room for exploration. Fanfictions can delve deeper into his time with Orochimaru, his family's past, and his relationship with Naruto from a different perspective.
Cinder is often still a popular character in the fanfic. Her journey and her strong character traits make her a central figure in many fan - created stories. Kai is also quite popular as he has a lot of potential for different storylines, especially in relation to his role as a leader. Thorne is another character that many fans like to write about due to his charm and his adventurous nature.
Yuki is a very popular character to focus on. She has a complex backstory, being raised among vampires and having a special connection to both the vampire and human worlds. Her relationship with Zero and Kaname also offers a lot of material for fanfic writers to explore, such as her inner conflict between her love for both of them and her duty to maintain the peace at Cross Academy.
Nagisa Shiota is also very popular. Fanfics could focus on his growth as an assassin and how his initially meek personality evolves over time. His unique skills and his friendship with other classmates can be great elements to build a story around.
Louise is a very popular character to focus on. She has a complex personality, being proud yet often insecure. Her growth as a mage throughout the series can be further explored in a fanfic, especially her relationship with her magic and how it evolves.
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.