One possibility is that Naruto is on a quest for self - discovery. Leaving the village to find the Sage gives him a chance to be away from the familiar and face new challenges alone. He might encounter different types of enemies and allies during this journey. This could also be a way for him to prove himself not just to the village but also to himself. He wants to show that he can grow and become stronger without always relying on the village's resources.
The title 'When leaves fall' in a Naruto fanfic could suggest a time of transition or reflection for the characters. It might involve a plot twist or a character's growth during this season.
Naruto might initially be in denial. He's so used to having Sakura around and believing that they have a future together. So when she leaves for Sasuke, he might think it's just a temporary thing or that she's been influenced by something or someone. But as time passes and he realizes it's real, he would be deeply hurt. He might also start to question his own self - worth, thinking that he wasn't good enough for Sakura. And he might even try to win her back at first, but then slowly come to accept the situation and focus on his other responsibilities like being a ninja and protecting the village.
In some fanfictions, Naruto might leave the Anbu due to internal conflicts within the organization. There could be corruption or power struggles. Naruto, being the idealistic character he is, would not want to be part of such a messed - up system. He might have discovered some dark secrets about the Anbu that made him decide it was not the place for him.
Naruto could encounter wandering ninjas who have their own stories and reasons for not being part of a village. Some might be outcasts due to their beliefs or powers, and Naruto's interaction with them could lead to either conflict or new friendships. He may also come across some of the shinobi who fought on the opposite side during the war but now have different outlooks on life. Through these meetings, Naruto gets a broader perspective on the ninja world.
In this fanfiction, perhaps Naruto's hidden jutsu legacy could be revealed. Maybe it shows some secret techniques that he developed but never got to show during the original series.
In this fanfiction, Naruto might leave the underworld because he has a mission to fulfill in the real world. Maybe he has to stop a new threat that endangers both the living and the underworld.
This type of fanfiction concept is really out of the ordinary. Naruto's character is built on his values of friendship, loyalty, and his dream of becoming Hokage. Killing Sasuke would mean betraying all of that. However, in a fanfiction, the author might be exploring the 'what - if' scenario. For example, what if Sasuke's actions against Konoha were so heinous that Naruto felt he had no choice? But still, it's a far - fetched and very different view from the original Naruto we know.
Often, Naruto starts off feeling sad and angry due to the neglect. He may become more withdrawn at first. Then, as he leaves, he gradually becomes more self - reliant. He has to fend for himself, which forces him to grow up quickly.
Naruto might meet another lost ninja. This ninja could be from a destroyed village. They would understand each other's pain and loneliness. Together, they decide to start a family, building a new life far away from the memories of their past tragedies.