Well, perhaps Naruto is constantly overlooked in his regular ninja training and tasks. So, he becomes intrigued by the secrecy and elite nature of the Anbu. In the fanfiction, he could befriend an Anbu member who secretly trains him. This leads to Naruto developing a dual identity, his regular self and his Anbu - inspired self, and he uses the skills he's learned to gain recognition in the village in a very unexpected way.
One possible plot could be that Naruto, feeling neglected by the village in some way, starts to idolize the Anbu. He might secretly train in the ways of the Anbu, observing them from afar. Maybe he discovers a conspiracy within the Anbu and has to decide whether to expose it or help fix it on his own while still being an outsider to the group.
In this fanfiction, Naruto's neglect might cause him to look for a sense of purpose elsewhere, like in the Anbu. He could start to study Anbu techniques on his own. As he delves deeper, he uncovers a connection between the Anbu and some of the village's darkest secrets. This makes him question the village's leadership. He might then try to reform the Anbu from the inside, using his new - found knowledge and his own sense of justice that has been shaped by his feelings of being neglected.
His relationship with his friends like Sasuke and Sakura would become more strained. Since he's focused on his secret Anbu - inspired activities, he might not have as much time for them. They might start to feel left out or worried about him. His relationship with the Hokage, whether it's Tsunade or someone else, would also be affected. The Hokage might view him as a bit of a renegade for his secret actions.
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.
One possible plot could be Naruto retiring from the ANBU due to the toll it has taken on his mental and physical health. He might then focus on mentoring the next generation of ninja in Konoha, sharing his unique skills and experiences.
One possibility could be that Naruto has been poisoned by a new and unknown enemy. This poison is slowly eating away at his life force, and he's trying to hide it from his friends and family so as not to worry them. He might be secretly seeking a cure while still fulfilling his duties as Hokage.
Maybe Naruto has always idolized the Hokage in secret. He could be studying the ways of past Hokages on his own, trying to learn their leadership skills and jutsu. For example, he might be secretly practicing Minato's Flying Thunder God Technique because he admires his father so much.
One possible plot could be that Naruto faked his death to go undercover in a powerful and evil organization. He pretends to be a new recruit while secretly gathering information to take the organization down from the inside.
One possibility is that Naruto is sent on a top - secret mission by ANBU. Maybe he has to infiltrate a powerful enemy organization. His disappearance could be part of a long - term undercover operation where he has to cut off all ties with his friends and the village for a while to avoid suspicion.
As the ANBU commander, Naruto would surely face many challenges. He'd have to deal with the politics within the ANBU itself. There might be some members who are resistant to his new ideas or way of doing things. Also, he'd need to balance his duties as a commander with his personal relationships, like his friendship with Sasuke and others. Maybe he'd use his position to try and bring Sasuke back to the village in a more official capacity as part of the ANBU's operations.
Well, in such a fanfiction, perhaps Naruto has just lost Sasuke again and is deeply depressed. The ANBU, seeing his skills and his need for a distraction, recruit him. He starts off being a bit of a misfit in ANBU, not following all the rules because of his independent nature. But as he continues, he starts to understand the importance of their work. He might even form new bonds with his ANBU comrades, which slowly help him come out of his depression.
One possible plot could be Naruto and Kurama having to work together on a top - secret ANBU mission. Naruto might have to rely on Kurama's power in a more covert way compared to his usual battles. Maybe they are sent to infiltrate an enemy stronghold where Naruto uses his ninja skills and Kurama's chakra to remain undetected.