One possible reason could be that he has become jaded after facing so many hardships in his life. He might have seen too much pain and loss, which has made him numb and less caring in the fictional scenarios of fanfiction.
Perhaps he has simply become too busy with other aspects of his life. If he has a new job, is studying intensively, or has more social obligations, he may not have the time or mental energy to engage with fanfiction like he used to. Fanfiction often requires a certain amount of time to read and get into, and if his schedule is packed, it's easy to let it go.
It might have a minor impact. If Harry was an active member of the community, his departure could mean one less reader and commentator. But overall, the community is large and diverse, so it may not be a huge deal.
It could be a result of a deal with a powerful and mysterious being. Naruto, in his quest to protect the village, makes a deal where he sacrifices part of his own essence. In return, he is given the power of the Hoshigaki, which slowly transforms him. He then has to figure out how to use this new power without losing his true self.
One possible reason could be a major ideological difference that has grown over time. Maybe Sasuke has adopted a more extreme view on protecting the village or avenging his clan that Naruto can't support. Another reason might be a misunderstanding that has festered. For example, if Sasuke was misinformed about Naruto's actions and intentions and has cut off ties because of it.
Well, while there might be some out - of - character fanfictions out there, the general perception of Naruto is that he is a very selfless character. His whole journey in the original story is about protecting others and achieving peace for everyone. So, in fanfiction, it's not very common for him to be portrayed as only caring for himself. Usually, the essence of his character is maintained, which is his altruism.
Perhaps it's a homage. Naruto respects the past Hokages a great deal, and Tobirama is an important figure in the village's history. Dressing like him could be Naruto's way of showing his respect and also inspiring the younger generation. He might want to show that the values and styles of the past are still relevant today, and by dressing like Tobirama, he can carry on that legacy in a more visual way. Also, it could be for a special event in the village where they are celebrating Tobirama's contributions and Naruto decides to dress the part to be part of the celebration.
One possible reason could be for protection. Maybe Naruto is hiding his true identity from an enemy who is specifically targeting him. He might be using the mask as a disguise to blend in and gather information without being recognized.
Perhaps Kabuto wants to use Naruto as a pawn in his own schemes. He might think that by reviving Naruto, he can control the situation in the shinobi world to his advantage.
It could be that Tora is attracted to the unique characters in Naruto fanfiction. There are so many different personalities and powers that might be appealing to a cat's curious nature.
Another reason could be related to Kakashi's past actions. If there are some secrets or things Kakashi did in the past that come to light and Naruto doesn't like them, he could snap at Kakashi. Naruto has a strong sense of justice and loyalty, so if he feels betrayed or misled by Kakashi, his reaction could be to snap.