One possible plot could be that Draco is turned into a kid by a misfired spell. His friends, who are used to his haughty self, now have to deal with a cute, innocent, and sometimes clueless kid - Draco. They might start to see a different side of him and form new bonds as they try to figure out how to turn him back.
In a Giyuu x Shinobu fanfic, the setting and plot can vary widely. Some might be set during the main events of the Demon Slayer universe, with them facing demons together. Others could be more of an alternate universe story, where they meet under different circumstances, like in a modern - day high school AU. The fanfic could also delve into their backstories and how those experiences shape their relationship. For instance, Shinobu's past with her sister could play a role in how she opens up to Giyuu, and vice versa for Giyuu's own traumas.
I would recommend 'Whispers of the Heart' for Giyuu x Shinobu fans. This fanfic focuses on their unspoken understanding. It's full of small moments that build up their relationship, like when Shinobu leaves a small flower on Giyuu's doorstep as a sign of her care. Also, 'Shadows and Sunlight' is worth checking out. It has a great plot that involves them having to go on a secret mission together and how that journey changes their relationship from colleagues to something more intimate.
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 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.