In addition to his friends, characters like Jiraiya might be involved. Jiraiya has a special connection with Naruto, and he would surely be worried about Naruto's situation. Tsunade could also be part of the story. She has the medical knowledge and authority to maybe find a solution to Naruto's transformation. And then there are the villagers. Some might be sympathetic, while others might see it as a chance to get rid of Naruto for good.
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.
The Akatsuki members could also play a role. They might be interested in baby Naruto either for his power or to use him as a bargaining chip. Also, Naruto's summons like the toads could be involved. They might sense something is wrong with Naruto and come to his aid. There are also the other ninja clans in the village. They could either offer help or be suspicious of Naruto's new form.
Obviously Naruto himself is the central character. Sasuke would also likely be involved. Given their history and Sasuke's own complex relationship with Konoha, he might side with Naruto or at least be a key figure in the events. Kakashi too, as he has been Naruto's teacher and is an important figure in Konoha. He could be caught in the middle, trying to understand Naruto's motives and also trying to uphold Konoha's stability.
In the 'yugi turns into a girl fanfiction', apart from Yugi's main group of friends, there could be some new characters introduced. Maybe a mysterious figure who knows the secret behind the transformation and can either help or hinder Yugi. Also, Yugi's grandfather might play an important role. He could be worried about his grandson/granddaughter and try to find a solution to reverse the transformation. And of course, the spirit of the Millennium Puzzle, Yami Yugi, would also be involved, perhaps having a different kind of connection with Yugi in this new form.
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, 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.
Obviously, Deku himself would be a main character even though he's turned into a baby. His friends like Uraraka, Iida, and Bakugo would also be main characters as they would be involved in taking care of him and trying to solve the problem.
Obviously, Itachi as a baby would be a main character. Sasuke would also be a key character as Itachi's brother. Their relationship would be very different now that Itachi is a baby. Naruto could also be involved, perhaps being curious about this strange transformation and wanting to help out in some way.
Obviously, Shikadai's parents would be central characters. His mother would be going through the process of pregnancy and childbirth, and his father would be there for support. Also, the medical staff or midwives in their world would be involved, taking care of the mother and baby during the birth.
There could be new characters specific to the village where he becomes Kamikage. For example, some powerful shinobi clans within that village. Their leaders would be important as they could be Naruto's allies or opponents. Also, the previous Kamikage's advisors might still be around and play a role in guiding or challenging Naruto. Maybe an old sage - like figure who has deep knowledge of the village's secrets and helps Naruto understand and respect the village's heritage.
Obviously, Harry and Ron would be highly involved. They are Hermione's closest friends. Harry would likely be the one leading the effort to find a solution, given his heroic nature. Ron, on the other hand, would probably be more involved in the day - to - day care of baby Hermione, with his big, caring heart.
In Naruto fanfiction, characters like Jiraiya could also be a 'baby daddy'. He was known for his womanizing ways in the series, so it's not hard to fathom a situation where he has a child. Then there's Itachi. Although his life was full of tragedy and secrecy, a fanfiction could explore a scenario where he has a child before his untimely death. And Kiba could be a character as well. His close bond with his dog Akamaru and his brash personality could lead to a situation where he becomes a 'baby daddy' in a creative fanfiction.