She could start by listening. Just being there to let Naruto vent out all the reasons for his hatred. Then, she might share her own wisdom. If she has some sort of special power or knowledge, she could use it to show Naruto that there's more to life than his hatred. For instance, if she can show him different futures or possibilities that don't involve him being consumed by hatred, it could be a start.
Well, if Naruto is consumed by hatred and there's a female Kyuu in the picture, their relationship could be really complex. Kyuu might try to reach out to the Naruto within the hatred. Maybe she'd use her own experiences to relate to him. For example, if she has had her own share of hardships that led to feelings similar to hatred in the past, she could share those stories with Naruto. It could be a bumpy start, but gradually they might find common ground and start to heal each other.
The plot could involve Naruto's hatred leading him to make some bad decisions. He might start to target his former friends and allies, believing they have betrayed him. The Fem Kyuu in this fanfiction could be an outcast herself. She sees something in Naruto that she can relate to and decides to help him, even at great risk to herself. They could go on a journey together where she slowly helps him understand the error of his ways.
The relationship could be a slow - burn type. Given Naruto's state of giving into hatred, he would be very guarded. The Fem Kyuu, on the other hand, would be the one making the first moves to connect. As they spend more time together, they might discover that they have complementary personalities. She could be calm and patient, which would balance out Naruto's now - angry and impulsive self. Eventually, their relationship could develop into a deep friendship or even something more romantic if the story takes that turn.
One possibility is that Naruto, filled with hatred, forms an unexpected bond with the female Kyuubi. Maybe the story could explore how they deal with Naruto's inner demons together. The fem Kyuubi might offer a different perspective on Naruto's struggle and help him find a way to overcome his hatred.
Naruto, being consumed by hatred, would likely become more brooding and intense. The fem Kyuubi could start off as a mysterious figure but gradually develop into a more empathetic character as she gets closer to Naruto. She might help him grow out of his hatred by showing him different ways of looking at his past and the world around him.
Power is a common theme. The demon lord usually has great power, and the fem kyuu in the harem may be drawn to that power or gain power through their association with him.
I'm not sure about a very specific one, but generally in these types of fanfictions, the relationship dynamics between the demon lord and the fem kyuu in the harem are complex. They often involve elements of love, loyalty, and sometimes rivalry. The demon lord may be seen as a powerful protector or a figure that the fem kyuu are both attracted to and a bit afraid of.
His friends would be worried and try to reach out to him. They might face rejection as Naruto, consumed by hatred, could push them away. For example, Sakura might try to talk some sense into him but be met with anger.
Naruto might also face hatred by becoming stronger. He trains harder and shows his opponents that he is not someone to be underestimated. For instance, if a group of rogue ninjas hates him because they think he's too idealistic, he proves them wrong by defeating them in combat and showing that his ideals are what make him strong.
One possible reason could be competition. Maybe in this fanfic, they are competing for something like recognition in the ninja world. Naruto, as a female, might feel that Sasuke is getting more attention or opportunities, which makes her jealous and eventually turns into hatred.