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.
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.
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.
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.
Another possibility is that Naruto travels to a time when the Uzumaki clan was facing a great threat. He could use his skills and knowledge from the future to help them. Maybe he teams up with young versions of his parents or other Uzumaki members to fight off the enemy. This could lead to a whole new understanding of his heritage and his own powers.
Gaara could be an important ally. He has always been Naruto's friend and as the Kazekage, he could provide resources and support for Naruto's plan to revive the Uzumaki clan. Maybe he could offer building materials to help rebuild Uzumaki settlements or send some of his shinobi to help with security during the revival process. Another possible ally is Tsunade. She is a Sannin and has a lot of knowledge and influence. She could help with medical research related to the Uzumaki clan, like finding ways to preserve their unique genetic traits or heal any potential genetic diseases within the clan. Also, she could use her political influence to get other villages to support Naruto's plan.