Naruto himself is often a popular character in such fanfictions. Since he has a strong connection with the bijuus, especially Kurama, his time - traveling adventures can create really interesting stories. Another popular character is Sasuke. His power and his complex relationship with Naruto can add depth to time travel plots.
In some popular 'naruto female bijuu fanfiction', characters like Hinata can often be reimagined as a female jinchuriki. Another common main character is an original female character created specifically for the fanfiction. Sometimes, Sakura is also given the role of a jinchuriki in certain fanfictions.
One interesting plot could be the main character traveling back in time and preventing the initial capture of the bijuus. This would completely change the power dynamics in the Naruto world. Another could be a character using time travel to team up with past jinchuriki to fight a new, greater threat.
A plot twist could be that the bijuu themselves have a collective consciousness that Naruto doesn't expect when he absorbs them. This consciousness could start to influence Naruto's actions during his time travels. For instance, they might guide him towards certain events or people that they believe are important for their own reasons. Maybe they want to correct some past wrongs in the ninja world that were related to their existence. This would add an interesting layer to the story as Naruto has to deal with not only the power of the bijuu but also their will.
Obviously Naruto is one of the main characters as the title implies his role as the master of bijuu. Other characters could include his friends like Sasuke and Sakura. Since it's related to bijuu, the jinchuriki of other bijuu might also be important characters, like Killer Bee who was the host of the Eight - Tails.
Well, Naruto is the obvious main character. However, depending on the plot, characters like Kakashi could be involved as well. He could be guiding Naruto in handling his godlike powers. And the villains in the fanfiction could also be main characters in a sense, as they would be the ones creating challenges for Naruto in his new state with the godlike bijuu powers.
In fanfiction, if Naruto is half - bijuu, it could mean he has enhanced physical abilities. For example, he might have greater strength and speed like a full - bijuu. His chakra reserves could also be much larger, allowing him to perform more powerful jutsu for longer periods.
It could have a huge impact. With Naruto absorbing all the bijuu through time travel, the power balance among the ninja villages is completely disrupted. Some villages that relied on their own bijuu for protection or status might lose their advantage. This could lead to political unrest as they try to find new ways to assert themselves. Also, the overall perception of power in the ninja world would change. Naruto would become an extremely powerful and perhaps feared figure, which could either inspire others to follow him or try to bring him down.
Sasuke is also popular. His brooding nature and his own complex journey make him a great character to include in time - travel plots. Fans like to see how he might be influenced by a time - traveler, especially if it affects his path towards revenge or redemption.
Sasuke is also a popular character in these fanfictions. In time travel scenarios, he might either be an ally or an antagonist to Naruto depending on the plot. For example, if Naruto's time travel changes Sasuke's past in a way he doesn't like, Sasuke could oppose Naruto.
Naruto himself is often a central and popular character. Since it's a time - travel story about him, his antics in the past are what drive a lot of the humor. His naivete in the past combined with his future knowledge can lead to some really funny situations.