Yes, there are. But it can be a bit of a search. You could try searching for specific tags related to Gon and Killua in addition to 'dom sub' on fanfiction archives. Keep in mind that different writers will have different interpretations of their relationship within the context of this kind of dynamic, so you may need to read a few to find ones that really resonate with you.
To write a Gon x Killua dom sub fanfiction, begin by researching the concepts of 'dom sub' relationships if you're not already familiar. Then, look closely at Gon and Killua's traits. Gon is often very determined and straightforward, while Killua has a more complex and guarded side. You can use these traits to build a story where one takes on a more dominant role and the other a submissive one. For example, a situation where Gon's single - mindedness in achieving a goal makes him seem dominant over Killua, who might be more submissive in that moment because of his admiration or respect for Gon. Also, make sure to write in a way that stays true to the overall tone of the Hunter x Hunter universe.
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.
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.
Yes, there are likely some fanfictions out there with such a concept. Fanfiction writers often come up with creative crossovers. You can try searching on popular fanfiction websites like Archive of Our Own or Fanfiction.net.
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.
I think Midoriya could be his best friend. Midoriya is kind - hearted and always looking to learn, which would appeal to Killua. They could bond over their shared desire to become stronger and protect others.
Often, they show a deeper level of commitment. The mpreg forces them to rely on each other more. For example, Gon might become more protective of Killua during the pregnancy.