Well, he might lose all his skills and knowledge at first. For example, he probably wouldn't be able to handle his sword as well as before. He could be really confused about his new small body and the world around him that now seems so much bigger. His friends would have to take care of him like a real little kid, feeding him, dressing him, and making sure he doesn't get into too much trouble. Maybe he would also start to see things from a completely different perspective, like being more innocent and curious about simple things that he used to take for granted.
If Deadpool is turned into a kid in fanfiction, it would be a total shift in his character dynamic. His relationship with other characters would change drastically. For example, his friends might have to take on a more parental role. And his enemies might not take him as seriously at first, but he could still surprise them with his child - like cunning. Also, his origin story would be interesting to re - imagine from a kid's perspective, how he discovers his powers and all that.
Well, in such a fanfiction, Sonic might lose his usual speed and confidence at first. He'd probably be more naive and rely on his friends more. Maybe he'd have to learn basic things all over again, like how to properly control his powers in his new, smaller form.
Well, he might have a whole new perspective on things. For example, his relationships with other characters would change. He'd probably have different interactions with Annabeth. Maybe she'd see him in a new light and they'd have to re - evaluate their friendship or more - than - friendship feelings. Also, his battles would be different as a girl. He might use his new - found femininity to his advantage, like using opponents' underestimation of a girl to surprise them in combat.
Well, he might lose all his evil cunning at first. Since he's a kid, he could start to see the world in a more innocent way. Maybe he'll make friends with people he used to terrorize, not realizing who they are. And he could be easily influenced by good-hearted characters, starting to develop a sense of right and wrong that's completely different from his adult, villainous self.
Well, in such a fanfiction, Naruto would be super cute as a chibi. He might have trouble being taken seriously by his friends at first. His powerful jutsu could look really funny in a smaller form, like the Rasengan might be like a tiny spinning ball in his little hands.
Well, he might have to rely on others for basic things like getting food. Since he's a cat, he can't open cupboards or cook. He'd probably be really frustrated at first, hissing at anyone who tries to touch him out of pride. But eventually, he might warm up to some people, especially if they give him fish.
Well, with his friends, they would have to adjust to his new state. Percy would rely on them a lot more. Grover might feel an even stronger need to protect him. And with other demigods, some might tease him while others would feel sorry for him. His relationship with the gods could also change. Some gods might find it amusing and not take him as seriously, while others might see it as an opportunity to manipulate him in his vulnerable state. His romantic relationship, if he had one, would be put on hold. His partner would have to wait until he's back to normal or might develop a different kind of affection, more like towards a little brother or something.
In the 'deku gets turned into a child fanfiction', it could lead to some really interesting storylines. Maybe he would see the world in a whole new way, with the innocence of a child. His interactions with his mentors could become more like a child - adult relationship where they have to guide him more. Also, his enemies might underestimate him at first, which could create some unique battle scenarios.
In this kind of fanfiction, Naruto might have to deal with a whole new set of powers and instincts. He would likely struggle with the urge to consume human flesh, which is a huge contrast to his usual values. Maybe he'd try to find an alternative way to survive, like the vegetarian ghouls in Tokyo Ghoul. His ninja skills could also be combined with his new ghoul abilities in interesting ways, for example, using his enhanced strength and speed from being a ghoul in combat while still relying on his ninja techniques like shadow clones.
Well, in such a fanfiction, probably Batman's sidekicks would have to take care of him. They'd be in a really strange situation, having to protect a baby Batman from the villains who might see this as a great opportunity to get rid of him once and for all.