Naruto Uzumaki is an obvious choice. Since he is a member of the Uzumaki clan, many fanfictions focus on his growth and development, often exploring his Uzumaki heritage in more depth. For example, some fanfictions might show how his Uzumaki blood gives him an edge in learning certain jutsus or in dealing with the Nine - Tailed Fox.
Well, he could start a family with Hinata and have lots of kids, passing on his Uzumaki bloodline. Then, he could encourage his friends who have some Uzumaki connection, like Karin, to also have families and pass on their Uzumaki genes. He could also set up a school or training center in the Uzumaki land, teaching the Uzumaki ways of life and ninjutsu, which would attract orphans or those who want to be part of 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.
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.
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.
The Akatsuki could also be antagonists in Uzumaki clan revenge fanfiction. They were after powerful ninja and the Uzumaki clan was full of power. They could have been the ones who initiated the attack on the Uzumaki clan to get their hands on things like the Uzumaki's powerful chakra or their sealing techniques. And then there might be a secret group within the Leaf Village itself that was involved in the Uzumaki clan's downfall, perhaps out of fear of their growing influence.
Naruto could also offer incentives for Uzumaki to have children. For example, providing better living conditions, education, and protection. He might also use his influence to find suitable partners for the remaining Uzumaki members, both within the village and from other allied villages. This way, they can start new Uzumaki families and gradually increase the clan's numbers.