Well, one possible plot could be that some sort of magic spell backfires on Grell. Maybe an experiment by a not - so - skilled wizard was meant to do something else but instead turns Grell into a baby. Then, the other characters would have to take care of baby Grell. They might struggle with things like changing diapers and feeding, all while trying to figure out how to turn Grell back to normal.
Mey - Rin could be a main character. Since she is a kind - hearted person, she would probably be very excited to take care of baby Grell. She might make little outfits for him and sing lullabies. And then there's Bardroy. He could be the one who is constantly worried about feeding baby Grell the wrong thing, like his cooking which is usually a disaster. But in the end, he manages to find some suitable baby food.
One idea could be that in this fanfiction, Wolverine turns into a baby due to a powerful mutant's accidental spell. The X - Men then have to take care of him while also trying to find a way to reverse the transformation. They might discover new aspects of Wolverine's personality as a baby, like his unwavering determination is now shown through his attempts to crawl towards danger.
One idea could be that a villain's new invention accidentally zaps Kim and turns her into a baby. Her sidekick Ron has to take care of her while also trying to find a way to reverse the effect. He might struggle with basic baby - care tasks like changing diapers and feeding her, all while keeping her safe from the villain who might want to take advantage of her weakened state.
One possibility could be that an akuma's power goes wrong and instead of attacking Chat Noir in a normal way, it turns him into a baby. Ladybug is then left to protect this baby Chat Noir while also trying to find a way to reverse the transformation. She might have to take him to Master Fu for help, all while hiding him from Hawk Moth who could potentially use this situation to his advantage.
One great fanfiction with this concept is 'Baby Dean's Adventures'. It has a really cute take on how the other characters deal with a baby Dean. They struggle at first but then it becomes a heartwarming story of protection and family.
One possible plot could be that the magic backfires on Voldemort during a powerful dark spell. As a baby, he has no memory of his previous self. The wizarding world is in chaos as they don't know what to do with this baby - voldemort. Some might want to kill him immediately, while others think he could be redeemed. Harry Potter, having defeated him once, feels a strange sense of responsibility and wants to make sure he doesn't grow up to be evil again.
Well, one possible plot could be that his friends have to take care of him. They might struggle at first, not knowing how to handle a baby Izuku. For example, Bakugo could be really frustrated but gradually learn to be gentle. Ochaco might be really good at soothing baby Izuku when he cries.
The plot could be that Deku is doing some sort of experiment in the school lab when something goes wrong. A chemical reaction or a malfunctioning device causes him to turn into a baby. All Might hears about it and comes to visit. He feels a sense of responsibility as Deku is his successor. The other students are both amused and worried. They start to learn about taking care of a baby, like feeding, changing diapers, and making sure he sleeps well. Meanwhile, the teachers are researching how to reverse the transformation, and they suspect that it might be related to some ancient quirk theory that they need to dig deeper into.
One possible plot could be that a magic spell gone wrong in Berk turns Hiccup into a baby. Toothless, being his loyal friend, tries to protect the baby Hiccup from the chaos that ensues. The other Vikings are confused at first but then start to take care of the baby Hiccup in their own clumsy ways, leading to some comical situations.