His relationship with Midoriya might change. Midoriya could become more protective of Todoroki as a girl, seeing her as more vulnerable. With Bakugo, there could be a different dynamic. Bakugo might initially tease Todoroki more, but as he sees Todoroki still being strong in her new form, he might develop a new respect for her.
In a fanfiction where Todoroki turns into a girl, his friendships at school would be transformed. His female friends like Uraraka might be more open and friendly, inviting him to do girl - only activities. The male classmates, on the other hand, might be a bit more awkward around him at first. Some might develop crushes on him, which would make things really complicated. And Todoroki himself would have to re - evaluate his relationships, learning to navigate the new social cues and expectations that come with being a girl in a hero - training environment.
His relationship with Kagome would change significantly. Kagome might see Inuyasha in a new light, perhaps more as a sister - like figure at first, but then as she gets used to the new form, there could be a shift in their romantic undertones. With Miroku, Miroku would be more respectful in a different way. He might be less likely to tease Inuyasha in the same way he did before. Sesshomaru, on the other hand, might initially be disgusted or confused by his half - brother's new form, but it could also lead to some interesting developments in their rivalry as Sesshomaru tries to figure out if this new Inuyasha is still a worthy opponent.
For Naruto, he might become more protective of Sasuke as a girl. Their friendship could take on a different dynamic, with Naruto being more chivalrous perhaps. Sakura might initially be jealous but then they could form a stronger bond as girls sharing common experiences. Kakashi would probably have to adjust his mentoring style to account for Sasuke's new situation.
Aang's relationship with the Air Nomads' spirits could also be affected. As a girl, she might be seen as a new form of the Avatar by the spirits. They could communicate with her in different ways, guiding her on a different path. This could lead to new alliances and ways of using air - bending that were not available to Aang when he was male. Also, her relationship with other female characters in different tribes could become more sisterly, with them sharing secrets and knowledge specific to women.
His relationship with Annabeth would be really interesting. At first, Annabeth might be shocked and a bit unsure how to act. But they could also develop a deeper understanding of each other as Percy now experiences things as a girl. With his male friends, like Grover, there could be some awkwardness, but also a chance for them to see Percy in a new light and strengthen their bond in different ways.
Well, in a Todoroki turns into a girl fanfiction, perhaps there's a villain who has a transformation quirk and uses it on Todoroki as a form of psychological warfare. Todoroki, now a girl, has to find a way to reverse the effect. In the process, he/she realizes that society treats female heroes differently and has to fight against those prejudices too. Maybe he/she even uses this new form to her advantage in some battles, by using the element of surprise.
His relationship with his parents would likely change. His mom might start treating him more like a daughter, perhaps with different rules or expectations. His dad might be a bit more protective. With his friends, the boys might be a bit more shy or awkward around him at first. And the girls might be more accepting and include him in their girl - only activities.
Well, Natsu's relationship with Gajeel could be really different. Gajeel might be more respectful towards Natsu as a girl, or he could be more competitive in a different way, like trying to prove that he's the better dragon slayer in a more gentlemanly manner. Natsu's relationship with the guild master, Makarov, would also change. Makarov might be more protective of Natsu as a girl, and Natsu might have to fight harder to be taken seriously in guild matters. In general, all of Natsu's relationships would be reshaped, with new levels of complexity and humor added to the story.
Well, with Kakashi, he might be more cautious in how he trains Sasuke. As a girl, Kakashi might have to consider different aspects of training, like physical limitations that might come with the female form. His relationship with his clan members, if they were still around, could also be different. They might have different expectations of a female Sasuke. And when it comes to the other male ninja in the village, some might be attracted to him, which would create some awkward or interesting situations.
His relationship with Sasuke would definitely change. Sasuke might be initially shocked and confused. He might see Naruto in a new light, not just as a rival but also as someone he needs to protect. Their dynamic could shift from pure rivalry to a more complex relationship with new emotions involved.
His relationships with his sisters would likely change. For instance, his older sisters might become more motherly or more competitive in different ways. His younger sisters could look up to him even more or be jealous of the new attention he gets. With his friends, some might be more hesitant to be around him, especially if they were only used to the male Lincoln. But some friends could also be very accepting and curious about his new experience.