Jugo himself is obviously a very important character. His struggle with his own powers and his connection to Orochimaru are key aspects. Then there's Kimimaro, another Jugo Clan member who was very loyal to Orochimaru. His backstory and his unique bone - related abilities are interesting to explore in fanfiction.
In addition to Jugo and Kimimaro, a fanfiction could focus on an older, wiser member of the Jugo Clan who has been in hiding for years. This character could hold the secrets of the clan's past and be a mentor figure for a younger Jugo Clan member. There could also be a character who is a hybrid, part Jugo Clan and part another clan, and their journey to understand and reconcile their two heritages.
Hiruzen Sarutobi is definitely one of the most important. As the Third Hokage, he has a wealth of knowledge and power. His actions and decisions have a huge impact on the clan and the village. Another important character could be Asuma Sarutobi. He is a skilled ninja and his relationships with other characters, like Shikamaru, add depth to the fanfiction.
A possible plot could be a Jugo Clan member going on a journey to find a way to control their clan's berserk state without relying on Orochimaru's methods. They could encounter various other clans and learn different techniques that help them in their quest. For example, they might study with the Nara Clan to gain better mental control.
Sasuke could also be an important character in this type of fanfiction. His relationship with Karin, whether it's a friendship, a rivalry or something more complex, can add depth to the story. Also, his own goals and powers might interact with Karin's Uzumaki - related activities. For instance, if Karin is trying to revive the Uzumaki clan's power, Sasuke might be interested in that power for his own reasons, like using it to fight against the enemies of the Hidden Leaf Village.
Obviously Naruto himself is a very important character as he is part of the Namikaze Clan. His father Minato is also crucial as he represents the previous generation of the clan. Kushina, Naruto's mother, could also be important as she was closely related to the Namikaze Clan through her marriage to Minato.
Hagoromo Otsutsuki is often a popular character. Since he is related to the Kaguya Clan, fanfiction writers like to explore his backstory and his connection to the clan's powers in more depth. His role in the creation of ninjutsu also makes him a fascinating character to include in Kaguya Clan - related fanfictions.
Often, characters who are hybrids of samurai and ninja traits are popular. For instance, a character who was born into a samurai clan but has an affinity for ninja techniques. They can bring a unique perspective to the story. Another popular type could be the wise old samurai master who imparts valuable knowledge to the younger generation, much like some of the respected ninja senseis in Naruto.
Shino Aburame is often a very popular character in Aburame Clan fanfiction. His quiet and mysterious nature makes him an interesting subject. Writers can explore his relationships with other characters, like Naruto, in more depth. He also has a lot of potential for character development, especially in terms of his bug - related abilities.
Well, Obito Uchiha can also be considered an iconic character in Rinnegan - related fanfictions. His connection to the Sharingan and his later acquisition of the Rinnegan through various means is a rich area for exploration. And, there could be an ancient ancestor of the Rinnegan Clan, a character only mentioned in the fanfiction, but whose legend looms large over the clan and its members.
Naruto himself is often a popular character in these fanfictions. Since he is the main character in the original series, he usually plays a significant role in stories related to secret clans. He might be the one to discover the secrets of a clan or help them in their struggles.
Often, the clan leader in Naruto Oda Clan fanfiction is a popular character. They are usually depicted as strong, wise, and having a great sense of responsibility towards the clan.