It could also be a new character created specifically for the fanfiction. This character might be an old hermit who has been living in Konoha in secret and is now passing on his knowledge of Fuinjutsu to Naruto or other characters. Maybe he has a special connection to the founding of Konoha and the original development of Fuinjutsu.
Well, they might have the ability to create extremely powerful sealing jutsus. For instance, they could seal away powerful demons or enemies with ease. Just like how the Fourth Hokage sealed the Nine - Tails in Naruto, the Fuinjutsu master could do similar things but perhaps on an even grander scale.
Well, perhaps the story starts with the fuinjutsu master being sent on a special mission. Along the way, he meets various female characters from different clans. As they see his amazing fuinjutsu abilities, they start to develop feelings for him. The harem aspect then kicks in as he tries to understand his own feelings towards them, all while using his fuinjutsu to solve mysteries and fend off enemies.
In Naruto fanfiction, the combination of Fuinjutsu and blacksmithing can be really interesting. Fuinjutsu is all about sealing techniques, and when combined with blacksmithing, one can imagine creating weapons with sealed powers. For example, a sword that has a sealing jutsu inscribed on it to trap the opponent's chakra when it strikes. It adds a whole new layer of creativity to the Naruto universe.
In such fanfiction, the blacksmith could be a master of both metal and seals. They might create a chain with Fuinjutsu that can bind an opponent's chakra. This would be a great addition to a ninja's arsenal. They could also work on larger items like gates with Fuinjutsu seals to protect a village or a secret location.
Sakura could be one of the main female characters. She's strong - willed and her medical ninjutsu skills could complement the fuinjutsu master's abilities. Another could be Hinata, with her gentle nature and Byakugan abilities. And maybe Ino, as she is also quite competitive and could add an interesting dynamic to the harem.
Well, Naruto is the central figure in these fanfics. But sometimes characters like Kakashi can play a significant role. He might be Naruto's mentor in the art of fuinjutsu, guiding him through the complex techniques and the history behind the seals. Jiraiya could also be a main character in some, as he was Naruto's teacher and had some knowledge of fuinjutsu himself.
One great 'fuinjutsu master naruto fanfic' is 'The Seal Master'. It shows Naruto's journey in mastering fuinjutsu in a really unique way, with exciting battles against new villains. Another one could be 'Naruto: Fuinjutsu Prodigy' which focuses on his training with an ancient master of seals.
One interesting aspect in Naruto fanfiction about Fuinjutsu in the Chunin Exams could be a character using unique Fuinjutsu techniques that were not shown in the original series during the exams. For example, a genin might create a sealing jutsu to temporarily disable an opponent's chakra flow in a creative way that surprises everyone.
Well, Naruto is an obvious choice. His connection to the Nine - Tails and his determination to master different techniques make him a central figure in many 'naruto fuinjutsu bloodline fanfiction'. Sakura might also be popular as she evolves in her skills and could be part of a story where she discovers a bloodline - related to fuinjutsu. Then there's Gaara. His unique sand abilities which could be related to a hidden bloodline in fanfiction and his connection to sealing jutsu in some storylines make him a popular character as well. There are also original characters created by fanfiction authors that can gain popularity within the specific context of this type of fanfiction.