In the fanfiction, Naruto's return from training could also lead to a change in his relationships. His friends might be in awe of his new strength and some might even feel a bit of distance as he has become so much more powerful. Also, he could use his new abilities to protect the village in a more effective way and gain more respect from the villagers.
The 'narusaku naruto returns from training fanfiction' could have Naruto coming back with a newfound confidence. Since he has been away for training, he might have a different perspective on things. Regarding his relationship with Sakura, he could start to see her in a new light. He may also bring back knowledge of new ninja techniques and strategies that could potentially change the way the village approaches combat and defense.
Naruto's character development in this fanfiction might involve him becoming more of a leader. With his new skills from training, he can inspire others and lead by example. He may also be more patient, having learned the value of hard work and perseverance during his training.
Naruto could become more mature. His time in training might have taught him patience and better control over his emotions. Sakura might also develop in response to Naruto's return. She could become more confident in their relationship, whatever it may be. And there could be changes in how other characters in the village view Naruto, seeing him as a more reliable and powerful ninja.
One possibility is that Naruto comes back much stronger and more confident. He might show off some new jutsu to his friends like a more powerful Rasengan. His return could also stir up the village as they see his growth and start to have new hopes for the future.
Naruto might also try to find alternative ways to gain strength. He could explore the forest around the village to find new training areas or discover new chakra - related phenomena. He has a curious nature, and this could lead him to stumble upon something that gives him an edge in his training, like a hidden hot spring that has special chakra - enhancing properties.
Definitely Gai. His whole shtick is about speed and he has amazing techniques like the Eight Gates. He can teach a lot about physical speed and the willpower needed to push one's limits. Also, Minato is a great choice. His Flying Thunder God Technique requires incredible speed and reaction time, so he could offer valuable insights.
In canon training scenarios, the training is often limited by the plot's pacing and the overall story arc of the Naruto series. But in serious training fanfictions, the training can be much more extreme. For example, in canon, Naruto's training with Jiraiya had a set structure and time limit. In fanfiction, that training could be extended indefinitely, with Naruto facing more and more difficult challenges. Also, fanfictions can introduce elements that are not part of the Naruto universe's canon. New types of ninjutsu or training tools can be added to make the training more unique.
One challenge could be readjusting to the village life. After intense training in a different environment, the daily routines and social norms of Konoha might seem strange. Also, he may face jealousy from some of his peers who haven't advanced as much in their skills during his absence. Another challenge could be dealing with the new threats that Konoha might be facing, and having to prove himself all over again to the village elders that his new skills are useful for the village's protection.
In fanfiction, Naruto's training might be more extreme or unique. For example, he could be trained by characters not present in the original. In the original, his training was mainly under Jiraiya and Kakashi, following a set path in the Naruto universe. But in fanfiction, he could be trained by an ancient sage from a hidden land, leading to different skills and power-ups.