Obviously Naruto himself is the main character as he is the one who turns into a baby fox. His friends like Sasuke and Sakura would also be involved. Sasuke might be initially confused but then determined to help Naruto. Sakura would probably be more nurturing and try to take care of the baby fox Naruto. Kakashi Sensei could also play an important role, using his wisdom to figure out what happened to Naruto and how to reverse it.
Obviously, Naruto himself is the main character in this situation. His friends like Sasuke and Sakura are very likely to be involved. They would be the ones taking care of him, trying to figure out how to turn him back to normal. Kakashi Sensei would also probably be there, guiding them and trying to keep Naruto safe.
Obviously Naruto himself, as he is the one turning into the Nine - Tailed Fox. Sasuke would also likely be involved. He might be the one to try and reach Naruto when he is in his fox - form, either to fight him or to bring him back. Sakura too, she could use her medical ninjutsu to try and help Naruto if he gets injured during the transformation.
Well, Naruto is obviously the main character as he has the nine - tailed fox within him. Then there's the fox god itself, which is a central figure in these fanfictions. Sometimes, other characters like Sasuke might be involved. Sasuke could be curious about Naruto's new powers related to the fox god or even be in conflict with Naruto when the fox god's influence changes Naruto's behavior.
The fox goddess is, of course, a main character in these fanfictions. Her powers and her nature are usually explored in great detail.
Definitely his friends from U.A. High. Bakugo would be an interesting character in this scenario. He might initially be annoyed but then develop a soft spot for baby Izuku. Ochaco would also be there, using her quirk in creative ways to take care of him, like floating toys to keep him entertained.
Well, one interesting plot could be Naruto having to rely on his friends in a whole new way as a baby fox. Since he can't communicate as he used to, his friends have to figure out his needs through his actions. Another plot might be that Naruto discovers new abilities or powers in his baby fox form that he didn't know he had before.
Obviously, Naruto is the central character. His relationship with the Nine - Tailed Fox is the core of this kind of fanfiction. The Fox itself, which is a powerful and mysterious entity within Naruto's body, is also a key character.
The villains in the Naruto universe could also play a role. Maybe the one who turned Naruto into a fox was an enemy seeking revenge or trying to gain some advantage. Orochimaru, for example, could be behind it, hoping to use Naruto's new form for his own evil experiments. And then Naruto, in his fox form, would have to fight against Orochimaru's minions to protect himself and his friends.
Maybe the main antagonist is an ancient spirit that has been awakened by Naruto's experiments with transformation. The spirit doesn't like Naruto's interference with nature's balance and decides to punish him by making him turn into a fox with the strange 'lemon' aspect. This spirit then tries to keep Naruto in this form permanently and drive him mad, so that Naruto can no longer be a threat to the spirit's plans of ruling over the ninja world.
Klaus Mikaelson is usually a central figure. His complex character and his role as a father in the fanfiction can lead to many interesting story developments. His relationship with the baby can range from over - protective to conflicted, depending on the plot.