He would become more confident. Having the powers of the Sage of Six Paths would give him an edge over his enemies. He would no longer be the underdog but a powerful force to be reckoned with.
His character would likely become more isolated at first. The new powers are so different from normal wizarding magic that he might have a hard time relating to his friends. But as he learns to control them, he could become more of a leader, guiding others in the use of these new powers if possible.
Naruto's relationship with the tailed beasts would transform into something truly unique. They would be more like equal partners in his journey as the Sage of Six Paths. As for his enemies, they would either be in great fear of him or would try to seek his power. But Naruto, being Naruto, would probably try to understand their motives and convert them into allies if possible. His new status would make him a central figure in the ninja world, and all relationships would revolve around his new power and the hope he represents.
In some fanfictions, the Naruto Six Paths Sage Technique can make a character more confident. Once they gain this powerful technique, they feel invincible and it shows in their attitude. For example, they might be more bold in their decision - making, not hesitating to take on powerful enemies.
In this fanfiction, perhaps the magic in the Harry Potter world is revealed to be a form of chakra. Harry discovers that he has the potential to be the Sage of Six Paths. He starts a journey to master this power. Along the way, he meets characters from both the Naruto and Harry Potter universes who either help or hinder him. This new power could also change the political and social structure of the wizarding world as it challenges the existing power dynamics.
In this fanfiction concept, the plot could be quite complex. Harry Potter, as the Sage of Six Paths, would have to balance his two very different power systems. He might discover that there are some dark forces in the wizarding world that are actually related to the ancient powers he now holds. He could start training other wizards in the ways of chakra control to create a new defense against the upcoming threats. His journey would be about not only mastering these new powers but also integrating them into the wizarding world's existing magic system without causing chaos.
It could be Voldemort still. Even with Harry having the powers of the Sage of Six Paths, Voldemort would be a formidable foe. He might be intrigued by this new power and try to steal it for himself.
Well, in the past, Naruto's ability to use Sage Mode might change significantly. In his own time, he has a certain way of gathering natural energy. But in the past, the distribution of natural energy could be different. He might have to learn a new method from the Sage of Six Paths himself. Also, his Rasengan could be improved. He could combine it with ancient jutsu knowledge from that era, creating a more powerful and unique version of the Rasengan. And his social abilities, like his knack for making friends and uniting people, would also play a big role. He could use these to gain allies in the past, which in turn could help him develop his abilities further as he would have more resources and knowledge at his disposal.
Naruto's ability to control the Nine - Tails would be enhanced. Since the Sage has a deep understanding of the tailed beasts, he could teach Naruto how to fully harness the power of the Nine - Tails without the usual struggle. This would make Naruto not only stronger but also more in tune with the beast's power, allowing him to use it more effectively in combat. He could also potentially communicate with the Nine - Tails on a much deeper level, leading to new forms of cooperation between them.
Naruto's character would likely become more mature. The Sage of Six Paths' training would expose him to greater wisdom, which would make him think more before acting.
In many fanfictions, Naruto as the Sage of Six Paths often has enhanced powers. He can use all six types of chakra natures more proficiently and on a much larger scale. For example, his fire jutsu might be as powerful as a sun's flare, and his water jutsu could create entire oceans. This portrayal gives him an almost god - like status in the fan - created stories, allowing him to face off against extremely powerful foes that he might not be able to in the original series.
Naruto could become more introspective. The power of the Sage of Six Paths is not just about physical strength but also comes with a lot of spiritual and historical baggage. He might start to question his own place in the ninja world and his destiny. He could become more withdrawn as he tries to understand the full extent of his power and how to use it for the greater good. However, his friends would still be able to pull him out of his shell when needed.