Ichigo would develop a more patient side. Halibel's different way of thinking and her more reserved nature would force Ichigo to slow down and really think about his actions. He would also become more protective, not just of Halibel but also of the new relationship they are building. Halibel would start to open up more. She was always a bit of an enigma in the original story. But in this fanfiction, being married to Ichigo would make her more expressive. She would start to share her thoughts and feelings more freely, and her character would become more complex as she tries to balance her old self with the new self that is influenced by Ichigo and his world.
One possible plot could be that Ichigo and Halibel initially struggle to understand each other's worlds. Since Ichigo is from Karakura Town and Halibel is from Hueco Mundo. But as they spend more time together, they start to learn about each other's values and dreams. They might face opposition from their respective groups, like Ichigo's friends might be skeptical about his relationship with a former Arrancar. However, through their love, they gradually break down those barriers and build a new life together, perhaps even uniting the two worlds in some small way.
For Ichigo, he could develop a more nuanced view of the Arrancars. Through his interactions with Halibel, he might realize that not all Arrancars are pure evil. This could make him more open - minded in his future encounters with other Hollows. As for Halibel, she could start to see the value in the Shinigami way, especially Ichigo's sense of justice. It might make her question her own loyalties and purpose.
In a post - war scenario, their relationship could develop into a mutual respect kind of thing. They've both seen the horrors of war, and they understand each other's strength. They might start to meet occasionally to exchange stories and advice on how to keep their respective groups safe.
In fanfiction, the idea of Ichigo and Halibel having a baby can lead to very interesting stories. It would combine the unique powers and personalities of both characters. For example, the baby could inherit Ichigo's Shinigami powers and Halibel's Arrancar abilities, creating a truly powerful and unique being. This concept could also explore how the two different worlds they come from, the Soul Society and Hueco Mundo, would react to such a union.
Well, it depends on what you consider 'good'. There are many out there, but the quality varies. Some might focus more on the action and power dynamics between Hollow Ichigo and Halibel, while others could explore a more emotional or romantic side of their relationship. It's best to read the summaries and reviews to find one that suits your taste.
Romance is also a common theme. Writers like to imagine a relationship between Ichigo and Halibel, which can be a really interesting take considering their different personalities and allegiances in the original story. It can range from a slow - burn relationship to a more sudden and passionate one.
Their powers could be combined in a way where Ichigo's Zanpakuto spirit, Zangetsu, and Halibel's water - based powers merge. For example, Ichigo could gain the ability to use water - enhanced slashes that have the cutting power of his normal attacks along with the fluidity of Halibel's water attacks.
To develop their relationship, start with small interactions. For example, the OC could save Halibel from a surprise attack by other Hollows. This would make Halibel curious about the OC. Then, have them exchange stories about their lives. Halibel could talk about her rise to become an Espada and the OC could share their origin story. Another way is to give them a common goal, like protecting a group of innocent Hollows from a cruel Arrancar. Working together towards this goal would bring them closer.
I really liked 'Vasto Lorde Ichigo's Encounter with Halibel'. It's a shorter fanfic but it packs a punch. It focuses on a brief but intense encounter between the two. The dialogue is sharp and the action scenes are well - written. It gives a sense of the mystery and power that surrounds both characters. You should definitely check it out if you want a quick and exciting read about them.
One common theme is power struggle. Given that both characters are quite powerful in their own rights, fanfictions often explore how they deal with each other in terms of strength. Another theme could be the exploration of the dark side of their personalities, as Hollow Ichigo is, well, hollow, and Halibel has her own complex nature.