Maybe Sasuke. Although they are rivals, they also have a deep bond. Sasuke might have come across a unique jutsu during his travels and decide to teach it to Naruto so that they can both become stronger and better protect their village.
It could be a new form of Rasengan. Maybe Naruto discovers a way to combine different elements with the Rasengan more effectively, like adding lightning to it for a more powerful and faster attack.
He might meet Iruka first. Iruka was always like a father figure to Naruto, and it would be a very heartwarming reunion. Iruka would probably be one of the first people to welcome Naruto back with open arms.
In the fanfic, Naruto could build the village by first establishing a set of rules and values that everyone can follow. Then, he'd probably use his connections. For example, he could ask his friends and allies from different villages to send resources or experts in construction. He might also use his own knowledge of the Leaf village's layout and infrastructure to create a similar but unique village. He'd ensure there are places for families to live, shops for trading, and of course, ninja training facilities. This way, the new village can thrive and be self - sufficient.
One interesting Naruto secret jutsu in fanfiction could be a time - traveling jutsu. It allows Naruto to go back in time and change certain events in the ninja world. This can lead to all kinds of new storylines and character developments.
In the fanfic, Naruto could offer a wealth of help to the Leaf. He might start by sharing his new knowledge and techniques that he has acquired during the process of making his own village. This could enhance the combat capabilities of the Leaf ninjas. He could also offer his strategic insights, which have been sharpened by his own village - building experience. Moreover, Naruto could help in terms of community building within the Leaf. He could promote unity among different clans and factions, just as he did in his own village. And of course, in times of crisis, his raw power and unwavering will would be a great shield for the Leaf.
The plot could involve Naruto coming back to the Leaf Village to fulfill a prophecy. He may have discovered something during his travels that made him realize he has a crucial role to play in the village's future. Along the way, he could face challenges from within the village, like some people being skeptical of his newfound knowledge or power. But through his determination and the bonds he has with his friends, he overcomes these obstacles and helps the village thrive.
Maybe it's to protect the village. He could discover a threat that he can only face away from the Leaf Village, to keep the danger from directly reaching his home and loved ones. He leaves as a form of self - sacrifice.
Naruto could respond with anger at first. He has given so much to the Leaf Village, and this betrayal would be like a slap in the face. However, his kind heart might also make him wonder if there is a misunderstanding. So, he could start by trying to communicate with the villagers he trusts. If that fails, he might leave the village for a while to get stronger and then come back to confront those who wronged him.
If Naruto has a new secret jutsu in fanfic, like a super - powerful healing jutsu, it could change the story by allowing him to save more lives during battles. For example, he could heal injured comrades immediately and keep them in the fight. This would boost the morale of his side and potentially change the outcome of many battles.