With Sakura, she might be initially scared of Naruto. However, as she realizes that he's still the same Naruto deep down, she could become more protective of him. She might also study more about the Kyuubi's transformation to try and help Naruto adjust.
His relationship with Sasuke would likely be very different. Sasuke might be more suspicious of Naruto at first, seeing him as an unknown entity. But as they learn more about Naruto's new situation, they could develop a deeper bond based on Naruto's unique perspective.
With Sakura, she might be initially scared but then come to see Naruto as someone she needs to protect even more. She could develop new medical techniques specifically to help Naruto in case the Kyuubi's power ever goes out of control. And she would probably be more in awe of his strength and try to learn from him how to be stronger herself.
Naruto's relationship with Sasuke might be different. Instead of the rivalry based on power and recognition, Sasuke could be more jealous of Naruto's unique bond with the female Kyuubi. Naruto's friends like Sakura might also view him with a bit of awe and fear initially, since he is being raised by such a powerful and feared being. The village elders would likely be more distrustful of Naruto, thinking that the female Kyuubi is influencing him in a negative way.
The relationship between Naruto and Sasuke might become more of a cat - like rivalry. They could be chasing each other around, or competing for the best spot in the sun. And Sakura might have to be the one to break up their little cat fights.
If Naruto were not human, his relationships would likely be very different. For example, his relationship with Sasuke might be more strained. Sasuke, who is very focused on power and revenge, might see Naruto as a greater threat if he's not human. He could view Naruto's non - human abilities as something to envy or fear. With Sakura, she might be more hesitant around Naruto. Instead of her initial crush, she could be more cautious, not knowing what Naruto is truly capable of.
Maybe in this fanfiction, Naruto has to hide his true nature from his friends at first. As he was once the Kyuubi, he might be afraid of being rejected. This could lead to some really tense and emotional moments when his friends start to suspect something is different about him.
Naruto's core personality might not change much. He'd still be the determined and enthusiastic ninja. However, as a girl, she might become a bit more sensitive to others' feelings. For example, she could be more empathetic towards Sakura's insecurities. Also, she might be more cautious in some situations, as society in the ninja world might have different expectations of girls. But overall, she'd still have that Naruto - like spirit of never giving up.
His relationship with Sasuke would be very different. With the Sharingan, Naruto would have a new connection to Sasuke's clan. Sasuke might see Naruto in a new light, perhaps as a rival in a different sense. They could have more complex interactions as Naruto tries to understand the Uchiha side of things.
Naruto's relationship with his mentor, like Kakashi, would face a big challenge. Kakashi would have to figure out how to train Naruto in this new form. Maybe he'd have to develop new jutsu specifically for Naruto as a fox. Also, Naruto's friends from the village, like Shikamaru and Choji, might treat him more like a pet at first, which Naruto would not be happy about, and this could cause some comical but also tense situations in their relationships.
If Naruto was turned into a monster in fanfiction, his relationship with the village would change drastically. The villagers who have finally started to accept him as a hero would once again be fearful. His friends would be divided in their reactions. Some, like Shikamaru, would immediately start thinking of ways to solve the problem. Naruto's relationship with his mentor, Kakashi, would be put to the test. Kakashi would have to balance his duty to the village and his loyalty to Naruto. And Naruto himself would feel isolated, which could further impact his relationships as he might become more withdrawn in his monster form.
His relationship with Sasuke would likely be affected. Sasuke might initially be suspicious of Naruto's new form, thinking it could be a trick by an enemy. But as time goes on, they could find new ways to work together. Naruto's new Kitsune powers could complement Sasuke's skills. For example, Naruto could use his enhanced speed as a Kitsune to keep up with Sasuke in combat.