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.
Another option is to ask in relevant social media groups dedicated to Hunter x Hunter. Fans in those groups might know of some well - written pregnant Killua fanfiction. However, keep in mind that not all fanfictions are of high quality, so you may need to read a few to find ones that you really like.
In a Naruto world fanfic, Killua would bring a whole new dynamic. He has a dark past as an assassin which could either make him a feared or respected figure. His family's training has made him physically and mentally tough. In battles, he could use his electricity - based attacks in creative ways against ninjas. But he would have to learn about things like jutsus and the ninja villages. Also, his relationship with Gon in the HxH world was important for his character development, and in the Naruto world, he might find a similar bond with a fellow shinobi, which could change his perspective on things.
As I mentioned before, 'lemon' implies adult content which is not suitable for discussion. So, I can't really talk about the characteristics of such fanfics.
He could form a rival - like relationship with Sasuke. Both are highly skilled and have a bit of a dark side. They might constantly compete to prove who's better in combat.
Gon in fanfiction can be very single - minded in his pursuit of goals, just like in the original. He might be a bit more naive at times, which can lead to interesting plot twists. Killua is often portrayed as having a complex emotional side. He struggles with his past as an assassin and his loyalty to Gon. His cool exterior may crack in some fanfictions, showing his true feelings.
I'm not sure specifically about a fanfic with that exact title. There are a lot of 'Killua x Gon' fanfics out there in the Hunter x Hunter fandom, but to find one with such a strange title would require some in - depth searching through fanfic platforms.
In 'killua x gon fanfic', the theme of sacrifice often appears. Killua or Gon might sacrifice something for the other's well - being. Another common theme is the power of their bond. It's often shown as something that can overcome great obstacles. And there's also the theme of shared dreams. They both have goals as hunters, and fanfics may explore how they pursue these dreams together or support each other in achieving them.
Adventure is also a popular theme. They go on quests together, facing powerful enemies and exploring new places. This allows for a lot of action and character development.
I'm sorry, but 'lemon' often implies adult or inappropriate content in fanfic terms. I can't recommend such works. However, you can look for regular Killua - related fanfictions on popular fanfic platforms like Archive of Our Own and filter them by positive reviews and appropriate ratings.