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.
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.
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.
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.
Hinata is often included. Her long - standing crush on Naruto makes her a natural fit in the harem. Sakura could also be part of it. Even though she had feelings for Sasuke initially, in the harem fanfiction context, her relationship with Naruto could develop in a different way. And then there's Ino, who is strong - willed and could add an interesting dynamic to Naruto's harem due to her competitive nature.
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.
The Akatsuki could also be antagonists in this fanfiction. They might see the Uzumaki bloodline as a threat or as a valuable asset to their goals. So they would target Naruto not just as a jinchuriki but also as the heir of the Uzumaki clan.
Naruto Uzumaki himself is often a very popular character in Uzumaki fanfiction. Since he is the main character in the original series and has Uzumaki blood, many fanfictions expand on his story, giving him new adventures or exploring different aspects of his powers.
Naruto himself is often a very popular character in these fanfictions. His connection to the Uzumaki clan and his growth as a ninja provide a lot of material for writers to explore. Hinata is also popular as she has a relationship with Naruto and her own unique abilities.
Well, surely there would be a main Uzumaki clan member, perhaps a young and determined one. They would be the driving force behind the revenge plot. There might also be a mentor figure, an older ninja who has some knowledge about the Uzumaki clan's past and can guide the main character in their journey.
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.