There's a possibility that Naruto turns to the dark side. After being banished unjustly, he could become angry and vengeful. He might start using his powers in ways that are not so heroic. However, his friends from the Hidden Leaf, like Sakura or Kakashi, could try to reach out to him and bring him back to the light. This would create a lot of internal conflict for Naruto as he struggles between his anger and his true nature.
Naruto might start to question his own identity. Being banished makes him feel like he doesn't belong anywhere. He could then start to explore his Namikaze heritage more deeply. He might discover secrets about his father that were hidden from him, and this knowledge could give him new strength and purpose. He could also use this newfound understanding to try and redeem himself in the eyes of the Hidden Leaf.
Maybe Naruto's connection to Pein through the Nine - Tails is misinterpreted. Since Pein was after the Nine - Tails, the village believes Naruto is a liability. Banished, Naruto wanders into a hidden land where he learns ancient ninja techniques that are far more powerful than what he knew. He could then return to the village as a changed and more powerful ninja, but with a sense of bitterness towards those who banished him.
One possible plot could be that Naruto is wrongly accused of something after the Pein attack. Maybe the village leaders believe false rumors that Naruto was in cahoots with Pein somehow. As a result, he is banished. He then goes on a journey to prove his innocence and in the process, he discovers new powers and allies. He might also encounter some of Pein's former followers who have their own motives and secrets related to what really happened during the attack.
One possibility is that Naruto's new 'godlike' powers after the Pain arc are seen as a threat by the village elders. They fear he might become uncontrollable, so they banish him. This could lead to Naruto exploring new lands, meeting new allies or enemies, and potentially finding a way to prove his worth and return.
It could be Danzo. He has always been suspicious of Naruto and might see this as an opportunity to get rid of him for good. He could spread false information to make the village turn against Naruto after the Pein attack.
It could be due to a curse. Maybe there is a long - forgotten curse placed on the Uzumaki clan, and Naruto accidentally triggers it. This curse slowly changes his nature and makes him more like Pein. His friends notice the changes but are initially powerless to stop it.
It could be the village elders. Since they banish Naruto, they could continue to be the main obstacle in his path. They might try to prevent him from coming back or try to eliminate him if they think he's a threat to their power and the village's stability.
One possible aspect of 'Naruto Namikaze Banished' fanfiction could be exploring Naruto's character development in this new and difficult situation. He would likely face many challenges being banished from his home. He might have to learn to survive on his own, find new allies, and perhaps even discover new powers or abilities.
One interesting plotline could be Naruto's struggle with PTSD after the Pein attack. He might have nightmares and flashbacks during his training or even in the middle of conversations, which could add a new layer of depth to his character.
One of the themes that often pops up is the search for identity. Without the framework of Konoha, Naruto has to figure out who he really is. He might question his loyalties, his goals, and his values. Friendship is also a big theme. We might see how his true friends react to his banishment and if new friendships are formed on his journey.
He could discover a new power within himself. Maybe during a particularly intense battle in the Chunin Exams, Naruto Namikaze realizes he has a latent ability that he didn't know about before. This new power could turn the tide of the battle and surprise both his opponents and allies.