Perhaps Kurenai first shows Naruto the real danger that lurks in the shadows of the village. She makes him understand that ANBU is the front line in dealing with these hidden threats. Then she tells him about how his growth as a ninja has led him to a point where he can handle such dangerous and secretive missions. She might also mention that by joining ANBU, he can gain more knowledge and power to protect not just the village but also the world from greater evils. Naruto, being the hero - type, would be swayed by such a grand vision presented by Kurenai.
She might convince him by showing him the long - term benefits for the village. For example, she could tell Naruto that in ANBU, he can prevent threats before they become major problems.
One possible plot could be that Kurenai has some sort of influence on Naruto's decision. Maybe she sees his potential in a different way than others. She could encourage him to join ANBU to better protect the village and its people. Naruto, being influenced by her words and perhaps having a sense of admiration for her, decides to take on the challenge of joining ANBU.
The Anbu sister could be a powerful and mysterious character. In the fanfiction, she might have unique abilities that Naruto is curious about. Their meetings could be filled with tension at first, as the Anbu are often secretive. But as Naruto's friendly nature breaks through, they start to share their stories.
One possible fanfiction could be about Naruto forming an unexpected bond with Kurenai's sister who is in the Anbu. Maybe Naruto stumbles upon her during a mission and they start to work together, gradually learning about each other's pasts and dreams.
For Kurenai, her character could be developed by exploring her relationships with other members of the village more deeply. For example, showing how she mentors the younger generation in addition to her regular duties. In the context of ANBU, she could be given a role where she has to train some of the ANBU recruits. As for Naruto, if he is involved, his time in the ANBU could show his growth in stealth and strategy, which are different from his usual combat style.
In some fanfictions, Naruto might join Anbu because of Sakura to prove himself worthy of her. Maybe he thinks that by becoming an elite Anbu member, he can show her that he's strong and reliable.
Another idea is a story where Naruto joins the ANBU and is paired with Kurenai for a special undercover operation. They have to infiltrate an enemy organization that is suspected of planning an attack on Konoha. Along the way, they learn more about each other's pasts and develop a strong bond as comrades.
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.
In this fanfic, Naruto might face tougher and more secretive missions. He could be trained in new and deadly ninja techniques specific to ANBU. Also, his relationships with other characters might change. For example, he might become more distant from his old friends as ANBU work often requires secrecy.
Well, in fanfic scenarios, the Anbu could protect Naruto by first gathering intelligence on all those who might pose a danger to him. This includes rogue ninjas or enemy villages. They'd then set up a perimeter around Naruto, using their various jutsu and combat skills to fend off any harm. For example, they might use their genjutsu to mislead attackers or their taijutsu to directly engage in combat if necessary.
Maybe in the fanfic, Kurenai has some actions that conflict with Naruto's beliefs. For example, she might oppose Naruto's way of handling certain village matters.