He could meet an old hermit who has some unique knowledge about chakra control. This hermit might be living deep in the forest where Naruto is training. The hermit could give Naruto some tips on how to better manage his chakra during his intense training sessions.
Maybe Naruto would encounter a strange animal spirit. This spirit could be attracted by Naruto's strong will and determination during his solo training. It could offer Naruto a new way of looking at his abilities and give him a special power boost or just some words of wisdom to help him in his training.
Well, in such a fanfic, Naruto might focus on mastering a new jutsu. He could be in a secluded area, like the forest near the village. He would practice over and over, facing challenges like controlling his chakra better. Maybe he'd also be thinking about how to become stronger to protect his friends and the village.
He might meet an old sage who has been living in seclusion near the village. The sage could see Naruto's loneliness on his birthday and offer him some ancient ninja knowledge.
He could meet an old enemy who has also changed after the war. This enemy might now be in a similar situation of being alone and they could form an unexpected bond as they understand each other's isolation.
He could meet other sannin. Maybe he stumbles upon Orochimaru who is on some secret mission. This encounter would be full of danger and Naruto would have to use all his skills and wits to survive.
He could meet some old enemies who have changed their ways. For instance, some of Orochimaru's former minions might have decided to start anew and cross paths with Naruto. Or perhaps he meets a hermit ninja who has been living in isolation for years and imparts some valuable wisdom to him.
In the fanfiction's training trip, Naruto may encounter some spiritual beings. These beings could be related to the origin of chakra or some long - forgotten ninja legends. Interacting with them would be a very different experience for Naruto. He would have to use not only his physical skills but also his wits and understanding of the ninja world's deeper mysteries to communicate with them. This could lead to a major transformation in his ninja journey, as he delves deeper into the spiritual side of the ninja arts.
There's a chance he'll meet other lost souls, people who are also on a journey of self - discovery. They could be from different villages and have their own reasons for being in the area. Naruto's positive attitude and determination might inspire them, and they could end up traveling together towards Uzu, sharing their stories and skills along the way.
He might meet an old acquaintance who is also alone. They could share their stories and perhaps find some comfort in each other's company.
He could meet an old hermit ninja who imparts his wisdom and knowledge to Naruto. This hermit might have been living in seclusion for years, but seeing Naruto's potential, decides to teach him things not found in normal ninja training.
Naruto might meet some foreign ninjas from far - off lands that have completely different fighting styles. These ninjas could teach him new ways to use his chakra and improve his combat abilities. He may also encounter some mysterious hermits living in the mountains or forests who possess great wisdom and unique jutsu. They could guide him on his journey of self - improvement and give him valuable advice on how to become stronger as a ninja.