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.
There could be a character from another clan who initially opposes the Uzumaki but later realizes the wrongdoings against them and joins the revenge cause. This character could bring in a different perspective and set of skills. And of course, there would be the antagonists, probably those who were involved in the downfall of the Uzumaki clan in the first place.
In addition to the Uzumaki protagonist, there may be some side characters who are friends or comrades. They could be from different backgrounds, like a common - born ninja who has a strong sense of justice and is inspired by the Uzumaki's cause. These characters would add depth and variety to the story as they support the main character in different ways during the revenge mission.
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.
Obviously Naruto Uzumaki himself. He is the central figure of the Naruto series and with the focus on the Uzumaki clan wars, he would be right in the middle of it all, using his skills and the power of the Uzumaki bloodline.
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.
One interesting plotline could be the discovery of long - lost Uzumaki clan jutsu. The protagonist might find ancient scrolls that contain powerful techniques that were thought to be lost with the decline of the clan. This could give them an edge in battles and also help in the revival of the Uzumaki's reputation.
One common plot is that Naruto discovers some long - hidden secrets about the Uzumaki clan's downfall. For example, he might find out that a certain group or individual was behind a massacre of his clan. Then he sets out on a journey to avenge them. He might train hard, learn new jutsus specifically related to the Uzumaki heritage to gain power. Another plot could involve Naruto teaming up with other characters who have a connection to the Uzumaki clan, like Karin. Together, they would face off against the enemies of the clan.
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 a group of rogue ninja who are after the Uzumaki's powerful sealing jutsu. They see it as a way to gain unlimited power and rule the ninja world, so they target the Uzumaki clan, which makes Naruto their main enemy as he stands in their way.
Perhaps an old enemy of the Uzumaki clan, long thought to be defeated, resurfaces. They see Naruto as a threat because of his position as the heir and aim to eliminate him before he can fully embrace his Uzumaki heritage and power. This could be someone with a vendetta against the Uzumaki for past events, like a clan that was defeated by the Uzumaki in the past and now wants revenge.