Maybe Naruto would meet some young Uzumaki clan members who look up to him. They would be inspired by his strength and his will to protect the village. Naruto could then take on the role of a mentor, teaching them the values he learned in Konoha and also some of his own ninja techniques.
Obviously Naruto Uzumaki himself is a key character. Then there's Kushina Uzumaki, Naruto's mother. She could be included through flashbacks or even some sort of spiritual guidance for Naruto. Another important character could be Nagato, who was also an Uzumaki. His story and powers could be explored further in relation to the clan. Also, any remaining Uzumaki clan members that are hidden or in exile could be introduced as new and important characters in the fanfic.
Perhaps Naruto would find ancient Uzumaki artifacts in the fanfic. These artifacts could have powerful abilities. He might have to face off against enemies who also want these artifacts for their own evil purposes. And through his interactions with the Uzumaki clan, he could gain new friends and allies who would stand by him in future battles.
The Uzumaki clan elders, even if they are not named in the original series. They could be important in a fanfiction. They could hold the keys to the clan's most guarded secrets. For example, they might know about a special Uzumaki training ground or a prophecy that involves Naruto and the future of the Uzumaki clan.
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 Uzumaki himself is the central character. His wife, Hinata, is also very important as she is part of his family and would play a major role in family - related storylines, like raising their children.
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.
Karui could be one of the characters. Since she is from the Hidden Cloud Village and has a connection to the Uzumaki clan through her son's relation to Naruto. Another could be Hinata. Although she is from the Hyuga clan, her love for Naruto and the Uzumaki influence on Naruto's life could bring her into the story. Also, Tsunade, as she has a connection to the Senju clan which is related to the Uzumaki clan.
It could be an unknown relative of Naruto. Maybe someone who has been living in a far - off place and just discovers their Uzumaki heritage.
His friends from Konoha like Sakura and Shikamaru might support him. Sakura could offer her medical skills to help any ailing Uzumaki members, and Shikamaru could use his intelligence to strategize for the clan's growth.
One possible plot could be a story of friendship. Karin, with her unique abilities, could team up with Naruto in some mission. They might start off not getting along well, but as they face challenges together, they develop a deep bond. For example, they could be on a mission to rescue some kidnapped villagers. Karin's sensory skills and Naruto's combat power would complement each other.