One possibility is that his relationships with other characters would change drastically. For example, his interactions with Saber might become more complex, perhaps evolving from a more traditional male - female dynamic to a more nuanced friendship or rivalry. His friends like Rin might also be very surprised at first but then gradually accept this new version of him. And in battles, his fighting style might be affected as well, since his physical form is different now.
In a fanfiction where Shirou Emiya turns into a girl, his appearance might lead to new character developments. He could attract new admirers or face new forms of jealousy. His new - found femininity might also give him new insights into the female characters around him. Maybe he would understand Saber's struggles as a female king better. And his clothing style would surely change, from the more masculine outfits he used to wear to something more feminine, which could also be a symbol of his new identity.
A plot possibility could be that Shirou has to keep his transformation a secret at first. He's afraid of how others will react, especially those he cares about. So he tries to act as normal as possible while dealing with the physical and emotional changes privately. Another could be that some sort of magic gone wrong caused the transformation, and he has to find a way to reverse it while also using his new form to his advantage in battles or other situations.
Well, one possibility is that he'd have to deal with all the social norms and expectations that come with being a girl in his world. Maybe he'd be shocked by how differently people treat him. For example, his male friends might be more protective or act differently around him. Also, he could discover new things about himself, like a different sense of fashion or a newfound interest in activities typically associated with girls.
In terms of the story's development, it could lead to a whole new arc. Naruto's transformation into a baby girl could be a sign of a greater threat to the ninja world. It might be related to some ancient curse or a new enemy's plot. And as he tries to figure out how to turn back, he would have to rely on his friends and his own inner strength in a different way than before.
Well, they could end up in a parallel universe. In this universe, the rules of magic are different. Shirou, Saber, and Archer have to figure out how to use their powers effectively. Saber might struggle at first because her usual combat style doesn't work as well. Archer could use his knowledge of different situations to help them adapt. And Shirou, being the main character, might have some sort of special connection to this new world that helps them survive.
Well, one thing that could happen is that Drake would have to deal with all the new social expectations. For example, he might be expected to act more demure or ladylike. His relationships with his friends, especially Josh, would also change. Josh might feel protective in a different way. Maybe Drake would start to notice how differently people treat him as a girl, like getting different reactions when trying to join in on all - boy activities. And he could use this new perspective to understand the girls around him better, leading to some really interesting and comical situations in the story.
Well, if Levi turns into a girl in the fanfiction, his fashion sense could be an interesting aspect. Maybe he would start wearing different types of gear. Instead of his usual plain style, he could end up with something more stylish yet practical. Also, his interactions with female characters would take on a whole new dimension. He might be able to better understand the struggles that female soldiers face in the Survey Corps. This could lead to him advocating for more equality within the military ranks.
In a fanfiction where Luffy turns into a girl, the story could take an interesting turn. Luffy's dreams of becoming the Pirate King wouldn't change, but the way he approaches it might. As a girl, he could use his charm to get out of some tricky situations. For example, when dealing with some of the more traditional pirates or marines who might underestimate a girl. Also, the Straw Hat crew's dynamic would shift. Zoro might be more protective, not that he isn't already, but in a different way. And Chopper would be super curious about the sudden change and would constantly be checking if there are any medical reasons for it, even though it's a magical fanfiction change.
Well, one possibility is that he would have to deal with the different social expectations for girls. He might start noticing how girls are treated differently in school, like in gym class where the activities for girls could be very different from what he was used to as a boy. Also, his relationships with his sisters would change in new and interesting ways. For example, his sisters might start including him in more of their 'girl - only' activities, like having a spa day or sharing fashion tips.
Well, Shirou might start by being in awe of the nature spirit. Maybe the spirit shows him some hidden parts of the natural world, like a secret glade filled with glowing flowers. They could form a bond where Shirou protects the spirit's territory from those who would harm it.
Well, if Sasuke turns into a baby in a fanfiction, one thing that could happen is that his friends would have to take care of him. Naruto, for example, might be really confused at first but then would become super protective. He'd probably try to feed Sasuke all kinds of strange foods that he likes, like ramen, not realizing that babies can't eat that yet. And Sakura would be all motherly, trying to keep Sasuke clean and making sure he's warm.