Another possibility is that she uses her intelligence as a human to find a way to reverse the vampire transformation. She could start researching in secret vampire libraries or seek out old vampires who might know a cure. Since she was turned, she might have a unique perspective that could help her in this quest, and along the way, she could make new friends or enemies in the vampire community.
Well, she might struggle with her newfound vampire nature. Maybe she has a hard time controlling her thirst for blood and accidentally attacks someone she cares about.
Well, she might struggle with her newfound vampiric nature. Maybe she would try to resist the urge to feed on humans, like Angel did. She could also find herself at odds with Buffy, who would be torn between protecting her sister and fighting the vampire she has become.
Well, he might struggle with his newfound thirst for blood. He'd have to deal with the wizarding world's reaction, which would probably be a mix of fear and fascination. His friends might be torn between helping him and being scared of him.
He could start to notice things from a different perspective. As a girl, Bakugou might become more aware of the way others perceive her appearance. She might also start to develop different interests, like taking more interest in fashion or something that she previously didn't care about. This could lead to some really interesting character development, especially if she still tries to hold on to her tough - guy (or now tough - girl) attitude.
He could find that his relationship with his Pokemon changes. Some Pokemon might be more protective of him now that he's in a more vulnerable form. Others might see him as less of a trainer and more of an equal. Ash would also have to deal with how the Pokemon world views hedgehogs. Are they seen as pests or something more interesting? This could lead to different reactions from different Pokemon species. And as he travels, he might discover new places that are more suitable for a hedgehog - like small burrows or areas with lots of bushes where he can hide and rest.
Well, one possibility is that he'd have to deal with all the social norms and expectations for girls in the wizarding world. Maybe she'd form different friendships, like getting closer to Hermione in a new way since they'd now share the experience of being female. And she might have a whole new perspective on the boys around her too.
Well, he might start having a different perspective on the magical world. Since sphinxes are known for their wisdom, Harry could use this new form to gain deeper insights into magic. He could also have a hard time communicating with his friends at first, as sphinxes have their own way of expressing things.
Perhaps Kaname would discover her disappearance and go on a quest to find her. Given his deep connection to Yuki, he would stop at nothing to get her back. He could use his pureblood vampire powers to intimidate those who kidnapped her into revealing her location.
Her relationships with her human friends will surely be affected. They might be scared of her at first, or she might be afraid of hurting them. So she may start to distance herself from them.
In the fanfiction, Kagome's enemies could underestimate her. They think that because she's a child, she's not a threat. But in reality, even as a child, Kagome still has her strong will and some of her powers. She could surprise them by using her wits and the little bit of spiritual power she has left to outsmart them. For instance, she could lead them into a trap that her friends set up.
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.