Well, one way could be in their physical abilities. Maybe in the fanfic, Naruto is shown to have some of Zetsu's stealthy movement skills, like being able to blend into the environment in a similar way. Another similarity could be in their connection to nature. Zetsu has a strong link to the plant - like aspects of nature, and Naruto's chakra might be shown to have a similar kind of connection in the fanfic.
There could be internal antagonists within Naruto's own village. Some of the more conservative ninja in the village might not trust Naruto's new - found skills and powers obtained from Zetsu. They could try to undermine Naruto or even attempt to exile him, fearing that he has been corrupted by Zetsu's teachings.
Obviously, Naruto and fem Zetsu are the main characters. Naruto, with his determination and dream of becoming Hokage, is the protagonist we all know. Fem Zetsu, on the other hand, brings her own unique set of abilities and a different perspective, being a part of the Zetsu race which has its own mysteries in the Naruto universe.
Naruto himself is a great choice. Their personalities are so different that it can create a lot of interesting interactions. Naruto's positive and determined attitude can contrast with fem Zetsu's more mysterious nature.
Sasuke would be a likely character to interact. Given their complex relationship throughout the Naruto series, Sasuke might be suspicious or intrigued by Naruto's control over Zetsu. Their interactions could range from confrontations to reluctant teamwork.
I'm not sure specifically as there could be many different interpretations in fanfiction. But it might involve Zetsu using his unique abilities to rescue Naruto from a dangerous situation, like a powerful enemy attack or a life - threatening trap.
In a fanfic where Naruto is trained by Zetsu, the story could take an interesting turn. Zetsu has knowledge of the Akatsuki and their secrets. Naruto could learn about the organization from the inside out. This knowledge could help him in his quest to bring peace. He might also gain some physical enhancements. Zetsu is quite durable in his own way, and Naruto could inherit some of that sturdiness. This would make him an even more formidable opponent in battles against strong foes like Pain or Madara.
The fanfic might explore new aspects of Naruto's character by comparing him to Zetsu. It could show different sides of Naruto that we haven't seen before, like his more devious or strategic side if he takes on some of Zetsu's traits. This exploration of character depth can be really engaging for readers.