One common theme is growth. Biscuit often serves as a mentor to Killua, so a lot of fanfics focus on his growth in strength and character under her guidance.
One popular fanfiction is 'The Adventures of Killua and Biscuit'. It takes them on a journey through a new and mysterious part of the Hunter x Hunter world. The author does a great job of portraying their unique personalities and how they interact.
One interesting fanfiction could be about Killua and Illumi's relationship evolving. Maybe Killua is trying to break free from Illumi's over - protective and controlling ways. They could end up having a heart - to - heart conversation where Killua makes Illumi understand that he needs to grow on his own terms.
One common theme in fanfics about Killua's sister is her growth and development. Writers may show her learning more about the world, becoming more independent, and perhaps even using her powers for good. She might go on adventures, similar to the main characters in Hunter x Hunter, and meet new and exciting people along the way.
A common theme is the conflict between their different paths. Killua wants freedom and to make his own choices, while Illumi is bound by the family's rules and expectations. Fanfictions often explore how they deal with this divide.
The themes usually revolve around family as well. His complex relationship with the Zoldyck family is often explored. Some fanfictions show him trying to reconcile with his family or completely break away. Adventure is another common theme. Since he's a Hunter, fanfictions often send him on exciting adventures, facing new monsters and challenges, which is in line with the spirit of the original 'Hunter x Hunter' series.
One common theme is growth. The reader often starts off as a relatively inexperienced character, and through their interactions with Killua, they grow both in terms of their skills as a hunter and in their personal relationships. For example, they might learn how to better control their nen abilities with Killua's help.
Many of these fanfictions also play with the idea of their growth as individuals within the context of their relationship. As Gon and Killua grow in power and experience in the 'Hunter x Hunter' world, their relationship also evolves in these fan - created stories. This can include how they deal with their own insecurities and how they support each other during difficult times.
Friendship is a very common theme. Gon and Killua have a strong bond, and many fanfictions explore how this friendship grows and endures different trials. For example, they might face a powerful enemy together and their friendship is what helps them get through it.
One great Killua's sister fanfiction is 'The Sister's Bond'. It delves deep into the relationship between Killua and his sister, exploring her character in new and interesting ways. It has some really engaging plot twists.