Obviously Naruto himself is extremely popular. Since the fanfiction is about his intense training, he is the central focus. Sasuke is also popular. His rivalry with Naruto often means he is included in training scenarios, either as a partner sparring with Naruto or as someone Naruto is trying to outdo. Kakashi is another popular character. As Naruto's teacher, he is often involved in guiding Naruto through his intense training.
One common theme is self - improvement. Naruto is always striving to get stronger in the original series, and in fanfiction, this is often amplified during intense training arcs. Another theme could be friendship. His friends might join him in training, and their relationships are deepened through shared hardships. Also, the theme of surpassing limits is popular. Writers like to show Naruto breaking through what was thought to be his maximum potential during these intense training scenarios.
In this fanfiction, Hokage Naruto might take Naruto to a special training ground. There, he could teach Naruto some of his own unique jutsu combinations. For example, he could show Naruto how to combine the Rasengan with his Sage Mode more effectively. This would give Naruto a huge power boost and also make him more confident in battles against tougher opponents.
Perhaps he's been influenced by someone who gives him bad advice. For example, if someone tells him that natural talent is enough and training is overrated. Also, he could be dealing with some personal problems, like a conflict within his family or among his friends that takes up all his time and mental energy, causing him to neglect training.
It could be due to the current situation in the village. There might be threats that required Naruto to stay. Tsunade, as the Hokage, had to consider the overall safety and stability of the village. So, she denied Naruto's request for the training trip to ensure he was available in case of any emergency.
In a Naruto Hinata training fanfiction, the author could explore Hinata's inner strength. Maybe she's training to overcome her shyness as well as improve her combat skills. Naruto, being the supportive friend, helps her break out of her shell. This could lead to some really interesting character development for both of them, and perhaps even a budding romance in the future.
In this type of fanfiction, the training could be a way for Hinata to prove herself worthy of being on Naruto's team for a special mission. She could be training day and night, with Naruto as her occasional sparring partner. As they train, they start to understand each other's motives and dreams better. This could be a really heart - warming story of friendship and mutual respect.
One common scenario is Naruto training with a new or unexpected mentor. For example, he might train with a powerful and reclusive shinobi from a far - off village who has unique techniques to teach. Another is training in a special environment like a pocket dimension filled with dangerous beasts that force him to quickly level up his skills. Sometimes he'll train in a team with other characters who also have something new to offer, like a combination of taijutsu and ninjutsu training that he hasn't experienced before.
Training in fanfictions often makes Naruto more confident. As he masters new skills, he becomes surer of himself in battles and in his interactions with others. For example, if he learns a powerful new jutsu, he'll carry himself with more pride and authority.
Well, it could make him more desperate to catch up. He might become more self - doubting at first. But then, as he realizes his mistake, he could develop a stronger sense of determination to overcome his lack of training. For example, he might start training in more unorthodox ways to make up for lost time.