In a fanfic about Hermione turning into a baby, it could be a part of a time - travel plot. The time - travel magic somehow affects Hermione and reverts her to a baby. Her intelligence as an adult might still be somewhat present in her baby form, leading to some comical or interesting situations. For example, she might try to communicate complex ideas using baby sounds and gestures, and her friends would be left trying to decipher what she means.
Perhaps in the fanfic, a mysterious artifact in the wizarding world is misused which turns Hermione into a 'baby factory'. The narrative could then explore how Hermione, despite her altered state, uses her intelligence in a different way. For example, she might be able to communicate in a unique way to help those around her understand what happened and how to fix it. And also, her friends like Harry and Ron would be in a race against time to figure out the solution before it's too late.
Harry would be extremely protective. He'd probably be the first to jump in and try to shield Hermione from any harm or unwanted attention. Ron, on the other hand, would be a bit more flustered at first but would quickly get his act together and use his loyalty to support Hermione.
It could be a jealous student who wants to undermine Hermione's intelligence. They might have cast the spell to turn her into a baby thinking it would be a great way to get her out of the way. This student could be someone who is always overshadowed by Hermione in class and exams.
Well, one possible plot could be that her friends have to take care of her as a baby. Harry and Ron might struggle to figure out how to keep her safe and fed. They could search for a way to reverse the spell that turned her into a baby.
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.
A great plotline could be the mystery behind who turned Hermione into a baby. It could be a dark wizard trying to stop her from achieving something in the future. As a baby, Hermione might start showing some unusual magical abilities that she didn't have before, which could attract the attention of both good and bad forces in the wizarding world. And her friends would be in a race against time to protect her and find a way to turn her back.
In a 'sakura turned into a baby fanfic', it could start with Sakura getting too close to a mysterious portal. The portal's energy zaps her and she is transformed into a baby. Her closest companion might notice some strange behavior before the full transformation. Once she's a baby, they need to protect her from those who might take advantage of her vulnerable state. They also have to deal with the challenges of taking care of a baby, like feeding, changing diapers, all while desperately looking for a solution to return her to normal.
Sakura herself would obviously be a main character, just in her baby form. Her best friend could also be a main character. For example, if she has a friend like Tomoyo, Tomoyo would likely be very involved. She would be trying to figure out how to help Sakura and also taking care of her, making sure she has cute clothes even as a baby.
Yes, there are some fanfictions out there that might explore such a concept. Writers like to play with different ideas in fanfic, and gender - swapping Harry Potter to create new storylines with Hermione could be one of them.