The main themes often include friendship and inspiration. Gai Sensei is such an inspiring character, and in these fanfics, his relationship with Naruto is based on mutual respect and friendship. Also, the theme of perseverance is prominent. Gai Sensei's unwavering perseverance in his own ninja way is passed on to Naruto, and we see Naruto face challenges with that same tenacity in the fanfics.
A great 'naruto gai sensei fanfic' that I know is 'Naruto and Gai Sensei: The Road to Success'. This fanfic really explores the potential of Naruto under Gai's mentorship. It details how Gai Sensei's energetic and positive attitude rubs off on Naruto. There are detailed descriptions of their training sessions, like the crazy physical exercises Gai makes Naruto do. It also shows how Naruto starts to adopt Gai's never - give - up spirit in his own ninja way.
In the fanfiction, Naruto's new sensei could be a mysterious figure who has ties to the Sage of Six Paths. This person might have been waiting for the right time to appear and train Naruto. They could possess knowledge about the origin of chakra and how to fully unlock Naruto's power. It could also be someone who was once an enemy but has now changed their ways and wants to use their skills to train Naruto for the greater good of the ninja world.
There's a chance that Naruto's new sensei could be a self - taught ninja who has developed their own unorthodox style. This person sees Naruto's ability to think outside the box and wants to refine that in him. They could introduce Naruto to a new way of looking at chakra control and combat strategies that are completely different from what he has been taught so far.
I think Orochimaru would be the most unexpected sensei. Usually, he's seen as a villain, but in a fanfiction, if he were to train Naruto, it would be extremely unexpected. He has a vast knowledge of jutsu, especially forbidden ones. He could teach Naruto some very powerful and unique abilities, but at the same time, Naruto would have to deal with Orochimaru's morally ambiguous nature.
He could have adventures in the Forest of Death. Anko has experience there, and she could take Naruto on more dangerous and secretive missions within that area. Naruto would learn how to better handle the perils of that forest.
Often, these fanfictions also incorporate elements from the Naruto universe like the use of jutsus and the presence of other characters. They might have Gai and Kakashi team up to fight a powerful enemy, and during this, their relationship deepens. This not only makes the story more engaging but also stays true to the original Naruto setting.
In a 'Naruto meets Gai' fanfiction, Naruto could learn some new and crazy ninja techniques from Gai. Gai is known for his unique and powerful combat style. Maybe Naruto would be inspired by Gai's unwavering determination and positive attitude, and it could lead to Naruto becoming even stronger both physically and mentally.
In this fanfiction concept, it could lead to a really interesting dynamic. Jiraiya is a powerful and eccentric ninja. He could teach Naruto some really unique jutsu, like more advanced forms of Rasengan. And their relationship would be filled with Jiraiya's boisterous personality clashing and also complementing Naruto's determination.
In fanfiction, Naruto as a sensei often has a very unique dynamic with his genin team. He might teach them his own unorthodox ninja techniques, like his signature Rasengan. His experiences as a former underdog also shape how he trains his students, emphasizing perseverance and the power of friendship.