Fanfiction about Killua's friendship with Gon and how it evolves over time is also very appropriate. We could see them face new challenges together, and how their bond deepens or is tested in different situations. It would be a heartwarming and positive way to explore the characters.
No, it's not appropriate. Fanfiction should focus on positive aspects such as character development, new adventures, or exploring relationships in a non - explicit way. Sexualizing a character in fanfiction goes against the spirit of most fandoms which are often family - friendly or at least should be respectful of all ages.
One common theme is power - up. When Killua crosses over into another universe, he often gains new abilities or finds ways to enhance his existing ones. For example, in a crossover with a superhero universe, he might learn to control a new type of energy. Another theme is friendship. He forms new bonds with characters from the other universe.
Another theme could be the relationship between Killua and the people around him, like his friends or family. For example, how Gon reacts to Killua's pregnancy and how they support each other. It could also touch on themes of love and sacrifice as Killua navigates this new situation.
Friendship or brotherhood is also a big theme. Despite their differences, many fanfictions show how they support each other in their own ways, like Killua relying on Illumi's skills in certain dangerous situations and Illumi having a soft spot for Killua deep down.
Adventure is also a common theme. The characters from Killua's world and RWBY's world going on quests together. They might be on a mission to stop a powerful enemy that threatens both their universes. This usually involves a lot of action scenes, battles against unique and powerful foes. And of course, there's often some element of mystery, like trying to figure out the secrets of the other world or the true motives of certain characters in the crossover.
Another theme is friendship. Killua is used to a certain type of friendship from his own story, and when he meets RWBY characters, new bonds are formed. It's about how he adapts to their group dynamic and vice versa. For example, his relationship with Ruby, who is very different from his friends back home.
Adventure is also very common. The OC usually gets involved in Killua's dangerous and exciting world of being a Hunter. They might be on a mission to find a rare item or defeat a powerful enemy. And there's often a theme of trust - building. Killua has to learn to trust the OC and vice versa.
Some popular themes could be friendship. In many fanfictions, Gon and Fem Killua might have adventures together that strengthen their bond. Another theme could be self - discovery. As they face different challenges, they learn more about themselves. Also, there could be themes of family, especially considering Killua's complex family situation in the original story.
One common theme is adventure. Since Killua is from the Hunter x Hunter world which is full of dangerous quests and exploration, many fanfictions involve the reader joining him on his adventures. For example, they might go on a journey to find a rare treasure or explore a mysterious and dangerous place.
Friendship is a very common theme. Since Gon and Killua have such a strong bond in the original work, fanfictions often explore different aspects of their friendship, like loyalty and mutual understanding.