She might be more empathetic. In the original, Orochimaru is quite cold and calculating. As a girl, she could still be intelligent and ambitious but also show more understanding towards others. For example, she might hesitate more before harming someone if she can sense their good intentions.
As a girl, Orochimaru could be more socially conscious. She might be acutely aware of the gender disparities in the ninja world. This could lead to her having a more rebellious streak against the traditional ninja hierarchy. She would not just be content with personal power but also strive to change the system that discriminates against female ninjas, all while maintaining her core traits of being highly intelligent and resourceful.
Her personality could become more nurturing. Maybe she would be more likely to take in and train young ninjas, especially female ones. She could see it as a way to empower them in a world that often undermines women. At the same time, she would still retain her slyness and ability to manipulate situations to her advantage.
Her personality might not change drastically. Sirius was always rebellious and brave, and as a girl, she would likely still be those things. However, she might become more empathetic as she experiences the world from a different perspective. Maybe she would be more in tune with the emotions of others around her.
Her personality might not change drastically at first. England is known for being reserved and proud. As a girl, she could still be those things, but perhaps be more in touch with her emotions. For example, she might be more likely to show when she's hurt or offended instead of bottling it up like she might have as a male.
Her personality might become more innocent. As a Kyuubi, she was powerful and perhaps a bit menacing. But as a little girl, she could be curious about the world around her, constantly asking questions. She might also be more vulnerable and seek protection from those she trusts.
Her personality might become more empathetic. As a girl, Percy could be more in tune with the emotions of others around her. For example, she might be quicker to notice when someone is sad or in need of help. In her previous life, she might have been more focused on her own goals and adventures, but now she could be more nurturing.
Her personality change could be influenced by the new experiences she has as a girl. For instance, she could be more fashion - conscious, which might seem superficial at first but could actually lead to a deeper exploration of self - expression. This newfound interest could make her more open - minded to different forms of art and creativity. Additionally, she might develop a more collaborative personality. Instead of always being the lone hero type as a boy, she could start to work more closely with others, especially other female characters, sharing ideas and building stronger relationships.
If Orochimaru were to turn Naruto into a girl in a fanfic, Naruto's personality could change in several ways. His boldness might be tempered a bit as he adjusts to his new form. He might become more cautious in some situations because he's now in a more vulnerable - looking body. However, his core values of loyalty and friendship would remain the same. He might also develop a new sense of femininity, which could add a new aspect to his personality. For example, he could be more nurturing towards his friends, something that was perhaps less emphasized when he was male.
She could become more assertive in a different way. Instead of the brash assertiveness Spike sometimes showed as a male, as a girl she might use her charm and diplomacy to get what she wants. For instance, when trying to convince Twilight to let her go on an adventure, she might sweet - talk her instead of just being pushy.
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.
She might be more nurturing while still maintaining her pride. For example, instead of just being boastful about military might, she could also boast about the cultural achievements of her nation, like art and literature, in a more motherly way.
She might become more assertive. In the Twilight series, Bella is often rather passive, but in the Mikaelson family, she would need to be more forceful to hold her own. She'd have to learn to be more cunning and strategic, like the Mikaelsons are.