First, you need a clear idea of why the character is deaged and what impact it'll have on the plot. Then, focus on showing the character's adaptation and growth in this new age. Also, don't forget to build interesting conflicts and resolutions related to the deaging.
First, think about the reason for the deaging. Is it a magic spell? A science experiment gone wrong? Then, focus on the characters' personalities as kids. For example, Tony Stark might be a super - smart but also a bit of a troublemaker as a child. Next, create a plot that involves them dealing with threats or challenges in their deaged state. You can also add some cute or funny elements like how they struggle to reach things or how they misunderstand adult concepts.
At first, Batman would be shocked and a bit confused. But quickly, his detective instincts would kick in. He would view the deaged Joker as a new and unexpected threat. He'd start gathering information about how the deaging occurred, in case it was part of a larger, more sinister plan. Batman would also be very careful not to underestimate the deaged Joker. He might try to isolate the Joker in a secure location to prevent him from causing chaos in Gotham. And he'd be constantly on the lookout for any signs of the Joker's old, devious self emerging from this new, younger form.
Weiss would probably be very protective at first. She has always had a bit of a mother - hen side to her, and seeing Ruby in a more vulnerable, deaged state would bring that out. She would likely try to keep Ruby out of trouble and make sure she was taking care of herself.
Well, it could be really interesting. The Avengers, being deaged, would enter Hogwarts as students. Tony Stark, even as a kid, would probably be a whiz at potions and charms that are somewhat similar to his technological inventions. Thor might struggle a bit with the more academic aspects but would be great at Defense Against the Dark Arts with his natural fighting skills. And Steve Rogers would be the model student, following all the rules and being a great leader among the young Avengers at Hogwarts. The interaction with the Harry Potter characters would also be fascinating. Harry could learn a lot from the Avengers' experiences outside the wizarding world, and Hermione would be eager to study the Avengers' advanced technology if it was possible in the magical setting.
They also change the relationships. His friends may treat him differently. Instead of being equals, they become more like protectors. And his enemies might underestimate him, thinking he's just a harmless child. This can lead to situations where Harry uses their false assumptions to his advantage, which is a big change from the original story. Also, the way the adults in the wizarding world interact with him changes. They may be more lenient or overly cautious, which alters the overall feel of the story.
One character that would be really interesting to pair with deaged Loki is Doctor Strange. Strange could be the one to help Loki figure out how to reverse the deaging process or use his new situation to his advantage. Also, if we consider the Avengers, Natasha Romanoff could be paired with deaged Loki. She could teach him some skills that he might not have learned in his original upbringing, like stealth and espionage. And Steve Rogers could also be a good match. Rogers' sense of honor and justice could have an impact on deaged Loki and maybe even inspire him to be a better person.
In fanfics, a deaged Harry Potter changes the plot in multiple ways. His deaged form means that his magical abilities are likely not as developed. So, in a fight against dark wizards, he can't rely on the same powerful spells he could as an older Harry. This forces other characters to step up and protect him. His relationships with the older characters become more of a mentorship or a protective one. For example, Snape might have a different attitude towards a deaged Harry, perhaps feeling a bit more sympathetic. Also, the plot may focus more on his growth and development as a younger wizard. There could be new storylines about him learning magic in a different way or exploring parts of Hogwarts he didn't pay much attention to when he was older. His deaged state can also introduce new mysteries, like why he was deaged and what it means for the future of the wizarding world.
In 'deaged Naruto fanfiction', usually Naruto is somehow magically or through some strange jutsu deaged. For example, he could be turned into a baby or a young child. Then the story explores how he copes with this new state.
In a well - known anime series, there is a character who is deaged into a baby girl due to a cursed artifact. Her friends have to deal with her new baby - like behavior while also trying to find a solution. They face challenges like feeding her, putting her to sleep, and at the same time, preventing her from getting into dangerous situations because she still has her adventurous spirit, just in a baby's body. This creates a lot of humorous and touching moments throughout the series.
When Draco is deaged in fanfiction, his character undergoes significant changes. His confidence, which was often a mask for his insecurities in his normal age, is replaced with a more genuine sense of self - discovery. He starts to question the beliefs that were drilled into him by his family. He becomes more reliant on others, which is a big change from his independent and aloof older self. He also becomes more adaptable as he has to quickly learn to live as a younger version of himself in a world that doesn't quite expect this new Draco.