I think Yamato could be a good choice too. His ability to control wood style could be really useful in the past. Maybe he could time - travel to help with the growth of the first trees in the ninja world or something like that. And his calm and collected nature would help him adapt to the new situation in the past.
Naruto's adaptation to the Anbu in this fanfiction could be a complex process. At first, he'd probably struggle with the strict discipline and the need for secrecy. But his previous experiences in tough situations would come in handy. He'd gradually understand the importance of stealth and how to use his skills in a more covert way. He might also learn from the more experienced Anbu members, and his own determination would drive him to become a valuable part of the Anbu.
Self - discovery is a significant theme. When Naruto travels back in time as an ANBU, he sees himself and the world around him in a new light. He discovers new aspects of his abilities and his personality. Additionally, the theme of secrecy and trust is common. As an ANBU, he has to keep his identity and mission a secret, but he also has to figure out who he can trust in this new timeline. This adds a layer of mystery and tension to the fanfictions.
A common theme is redemption. Naruto often goes back in time to correct his past mistakes or the mistakes of others. For example, he might try to save a character who died in the original timeline. Another theme is power - growth. Since he has knowledge from the future, he can train more effectively in the past and become even stronger.
I really liked 'Anbu Naruto's Time - Twisted Adventure'. In this fanfic, Naruto goes back in time and joins the Anbu much earlier. It's full of action and there are some really cool fight scenes. The author also does a great job of exploring how Naruto's time travel affects the relationships he has with other characters.
One possible scenario in such a fanfiction could be that the Anbu Commander travels back in time to prevent a major tragedy in the Naruto world. Maybe he goes back to stop the Uchiha massacre. He could use his knowledge of future events and his Anbu skills to change the course of history.
One interesting concept could be how Ichigo's character might change in the reincarnation and time travel scenario. Maybe he has memories of his past life that influence his actions in the new timeline.
Perhaps a new character created specifically for this fanfiction. This new antagonist could be someone who wants to use the power of reincarnation and time travel for their own evil purposes, like trying to rewrite the world to their liking and is opposed by Ichigo and Kaien.
Some of the more hot - headed ANBU members might overreact and assume Naruto is a threat to the village. They could try to use force to get the stolen item back. However, the more level - headed ones might try to figure out Naruto's motives first. They might consider that Naruto could have a good reason for what he did, like if he thought the item was being misused by the ANBU.
One interesting storyline could be Sakura joining the Anbu and having to prove herself among the male - dominated group. She might face challenges like secrecy requirements and intense training, all while Naruto is on his own journey, and their paths cross in unexpected ways during missions.