In a fanfiction, the fem Sage of Six Paths could be from a parallel dimension. Naruto accidentally stumbles upon a portal and meets her. She has a different understanding of chakra and its uses. Naruto is intrigued and they decide to exchange knowledge. As they do so, they face opposition from some within the shinobi world who fear the change this new knowledge might bring. They have to fight against this prejudice and also against a dark force that is trying to use the chaos to take over.
Maybe the fem Sage of Six Paths is reincarnated in the modern era of Naruto's world. Naruto is initially skeptical but soon realizes her power and knowledge. She reveals that there is a prophecy about them working together to bring about a new era of peace. So, they start training the new generation of shinobi together, combining their different styles and teachings, which also leads to some romantic undertones between them.
Well, it could be about Naruto discovering his connection to the Sage of Six Paths as a brother and using that newfound knowledge to gain stronger powers. Maybe he'd unlock some hidden jutsu passed down through their family line.
Well, it could be about Naruto coming back as the Sage of Six Paths and having to face a new, even greater threat that was hidden during his first life. Maybe an ancient evil that the Sage of Six Paths had sealed away long ago but is now starting to break free.
A good antagonist could be a rogue ninja who has somehow managed to gain some of the power of the Otsutsuki clan. He wants to use the fem Sage of Six Paths' connection to the origin of chakra to open a gateway to a world full of power that he can rule. He sees Naruto and the Sage as threats to his plan and constantly tries to sabotage their efforts to protect the world.
One interesting plot could be about Naruto exploring more of the Sage of Six Paths' untold teachings. For example, he discovers a new jutsu that was lost in time but was once known to the Sage. This could lead to him becoming even more powerful and facing new threats in the ninja world.
One idea could be exploring the training of Naruto by the Sage of the Six Paths in more detail. Maybe the Sage could teach him some long - lost jutsu. Another idea is to have Naruto travel back in time to the era of the Sage and witness the creation of ninjutsu first - hand.
One possibility could be that Naruto uses this new power to finally bring true and lasting peace to the ninja world. He might be able to use it to end all the remaining grudges and rivalries among the different ninja villages. For example, he could use his Sage of Six Paths power to create a new system where all villages share resources and knowledge equally, thus eliminating the need for competition and war.
Well, it could be about Naruto getting some super powerful training from the Sage of Six Paths. Maybe he learns some new jutsu that no one has ever seen before.
One idea could be Naruto having to face an ancient evil that threatens to disrupt the balance between the six paths and the avatar world. He might have to learn new jutsu inspired by the avatar elements. Another could be Naruto forming an alliance with avatar characters to fight a common foe, like a powerful dark spirit that can cross between their universes.
Perhaps a plot where Naruto has to teach the Sage of Six Paths Senjutsu to a new generation of ninjas. This could involve dealing with their different learning abilities and personalities, and also facing threats from those who want to misuse this powerful technique. It could also show how Naruto has grown as a teacher and a leader.
One idea could be Naruto traveling to a different universe where the Sage of Six Paths is still alive and they team up to face a new, powerful enemy. Another could be a fusion of their powers in a strange way due to a magical artifact in the crossover world. Maybe Naruto gets to learn new jutsu directly from the Sage in a more in - depth way than he did in the original story.