In some fanfictions, Naruto's life in Anbu could lead to a significant change in his character. He may become more withdrawn and brooding as he deals with the darker side of the ninja world that Anbu often encounters. His relationships with his friends might also be strained as he has to keep parts of his Anbu life a secret. This could create a lot of drama and tension in the story.
In ANBU fanfictions about Naruto and Iruka, their relationship often takes on new and exciting dimensions. Naruto, with his usual exuberance and determination, might be guided in the more secretive and dangerous ANBU world by Iruka. Iruka, being a caring figure in Naruto's life, could be a source of stability for Naruto as he faces the harsher aspects of ANBU missions.
In fanfiction, Naruto and Kakashi in ANBU could have super intense and covert missions. Maybe they are sent to infiltrate a powerful enemy base. Naruto with his unpredictable ninja skills and Kakashi's experience would make a great team. They might face enemies with unique jutsus and have to rely on each other to survive and complete the mission.
If Naruto's friends or loved ones are threatened by the ANBU, either directly or indirectly. For instance, if the ANBU's actions put Sakura or Kakashi in danger without just cause, Naruto would be likely to turn against them. He's very loyal to his friends, and any threat to them would be a strong motivation for him to take action against the ANBU.
One possible plot could be her facing a mysterious enemy within the village who is trying to undermine the ANBU. She has to use her unique skills and knowledge of the village to uncover the traitor. Since she's female in this fanfic, she might also face discrimination from some of the more traditional ANBU members at first, but she proves herself with her combat and leadership abilities.
His character could become more jaded. In the ANBU, Naruto would have seen a lot of the darker side of the ninja world. He might be less naive and more calculating. For example, he would be more hesitant to trust people immediately like he used to.
In this fanfiction, Naruto as an ANBU Captain Kitsune could be faced with a powerful and mysterious enemy. He has to draw on his inner Kitsune strength and his knowledge of the ninja world. He might also have to make tough decisions that test his loyalty to the village and his comrades. His Kitsune heritage could give him an edge in battles, with abilities like enhanced speed and the power to manipulate chakra in new ways.
It could be Itachi. Even though Itachi has his own complex past, he is highly skilled in Anbu - like operations. He could show Naruto the ropes of the Anbu world, teaching him how to analyze situations quickly and make tough decisions that are often required in Anbu missions.
One scenario could be that Naruto and Sakura are on an undercover mission in ANBU. They have to pretend to be a couple to get closer to the target. As they act out this role, they start to feel real emotions for each other. Naruto's warm personality makes Sakura feel safe, and Sakura's intelligence helps Naruto in the mission. Eventually, they find it hard to distinguish between the act and their true feelings.
One possibility is that Naruto joins the Anbu to prove himself even more. He might face challenges like learning the stealthy ways of the Anbu which are very different from his usual open - combat style. He could also be sent on dangerous solo missions that test his limits both physically and mentally.
In fanfiction, Naruto and Anko Anbu could have a mentor - mentee relationship. Anko, being an experienced Anbu, could teach Naruto some of the more stealthy and darker aspects of the ninja world that he might not learn otherwise. Maybe she'd show him some unique jutsu or how to better handle dangerous missions.