In a Naruto in diapers fanfic, the author has the freedom to create new settings and scenarios. They can introduce new characters who are involved in taking care of baby Naruto or create new challenges that are specific to his baby - like situation. This can lead to a lot of creative and unexpected plot twists.
One possible plotline could be a comical take where Naruto, perhaps as a baby or in a situation where he's regressed to a younger state in diapers, accidentally uses his newfound baby - like clumsiness to his advantage in a prank - like way against his friends. For example, he might 'accidentally' spill something on someone while being carried, leading to a series of funny events.
A 'back to diapers fanfic' might be centered around a specific fandom. Say, if it's related to a superhero fandom, a hero might be cursed or affected by some magic that makes them regress to a state where they need to wear diapers. This could then explore how the other characters in the story react to this change, how the affected character copes with this new and embarrassing situation, and how it impacts the overall dynamic of the fictional world within the fanfic.
There might be such a fanfic out there, but it's not a common or mainstream type of fanfic. Some niche or more experimental fanfic writers may have explored this idea, but it could also be that it doesn't exist at all. You could try searching with specific keywords related to 'ciel' and 'diapers' in the fanfic search engines of different websites.
There could be. The world of fanfiction is extremely diverse, with writers exploring all kinds of unusual scenarios for their favorite characters. 'Harry Potter Wears Diapers' might be a humorous or alternative take on the character by a creative fan writer. But it may not be easy to find as it's not a common or typical fanfic theme.
One key element is the diaper itself. It often becomes a central part of the story, whether it's about the pony getting used to wearing it or the reactions of others to it.
It's difficult to say if there are truly 'popular' 'back to diapers fanfic' stories in the traditional sense. Since this is a rather specific and often unusual theme, it's more likely to be something that exists within small, dedicated fan groups. These groups might have their own favorites, but they may not have reached a level of popularity that extends far beyond their own circles. Maybe in some very specific fandoms with a particular taste for this kind of regression - themed fanfic, there could be some stories that are more talked about among those fans.
It might be used to illustrate a particular character's situation. For instance, if there is a character who is shy about wearing diapers at school because of peer pressure. The story could be about how they overcome this shyness and gain confidence.
I'm not sure specifically as it's a very strange and likely non - canon fanfic concept. It might be some sort of very out - there, perhaps dark - humor or extremely alternate - universe take on the Harry Potter world where Nagini, Voldemort's snake, has this rather odd and inappropriate interaction with Harry. But without reading it, it's hard to say exactly.