The main characters would surely include Nightwing in his baby form. Then there could be other superheroes or sidekicks who might come across baby Nightwing. For example, Huntress could be one of the main characters if she stumbles upon the situation and decides to help. And of course, the villains who might have caused this transformation could also play a major role, as the heroes would be trying to stop them from causing more harm and also find a way to reverse what they've done.
Obviously, Nightwing himself, even as a baby, would be a main character. His friends in the Bat - family like Batman, Robin, and Oracle would also be main characters. They would be the ones dealing with the situation of baby Nightwing.
In this type of fanfiction, Nightwing as a baby is a central character. Additionally, any of his long - time allies in the Gotham vigilante scene could be main characters. Alfred, the butler, could be a very important character. He would be the one with the most experience in taking care of someone, so he would be crucial in looking after baby Nightwing. Also, any villains who are related to the cause of his transformation, such as a mad scientist type of villain who created the device or spell that turned him into a baby, would be main characters as well.
Batman could be a main character. Since Nightwing was trained by Batman, in a baby Nightwing fanfiction, Batman could be the one taking care of him, teaching him basic skills, and protecting him from the threats of Gotham.
Well, one possible plot could be that a villain casts a spell on Nightwing. His friends then have to take care of baby Nightwing while trying to find a way to reverse the spell. They might discover new and cute things about him, like his love for a particular toy or food.
In addition to the usual suspects, there could be some new characters introduced. For example, an old Pokémon trainer who has seen similar things before and can offer some advice on how to deal with baby Ash. Or a mysterious Pokémon that has the power to either help or hinder the process of getting Ash back to normal.
Tomoyo would also be an important character. She would be very worried about Sakura. She might use her skills in making costumes to create some special baby clothes for Sakura. And she would be constantly by Sakura's side, taking care of her and trying to comfort her.
Another possible main character could be a wise old mentor figure. This person might have knowledge about these strange transformations. They could guide Nico's friends or family in their quest to turn Nico back. Maybe this mentor has been around for a long time and has seen similar magic used in the past, so they know where to start looking for answers.
His friends Orihime and Chad would probably be main characters. Orihime could be very motherly towards baby Ichigo, always making sure he's comfortable. Chad would be the strong protector, making sure no harm comes to the baby.
A wise old wizard in the story could be a main character. He has the knowledge and power to potentially reverse the spell on Leo. He guides Leo's friends and family on their quest, providing them with clues and magical items that are needed to solve the mystery of turning Leo back.
The Akatsuki might be the main antagonists. They might think that a baby Sasuke is easier to capture and they could use him for their own purposes, like extracting his Sharingan or something else related to his power. They would be a great threat as they are powerful and cunning.
Definitely Aunt May. She would be super worried about baby Peter and would do everything she could to take care of him. She might even call in some old friends or neighbors to help out.
Sakura could be a main character. She might be the one who takes on a motherly role towards baby Naruto. She'd be very protective and try to teach him basic things. Kakashi could also be important. He'd use his wisdom to figure out how to deal with this situation and also keep an eye on Naruto's safety.