Gon would probably be angry at first. He has a strong sense of justice and being kidnapped against his will would surely make him mad. He'd try to fight back immediately if he had the chance.
In some fanfictions, Gon might initially be shocked. He has seen Hisoka as a somewhat eccentric but strong ally. When he discovers Hisoka's more sinister side, like his love for fighting to the death and his disregard for normal moral boundaries in battle, Gon could be conflicted. He might feel a sense of betrayal because he thought Hisoka was more on the side of 'good' in their adventures. However, Gon's own sense of justice and his unwavering belief in his friends could lead him to confront Hisoka about his true nature.
Killua is likely to be completely devastated. He might go into a state of shock at first, not believing that Gon is really gone. Then he could become very angry, either at himself for not being able to protect Gon or at the situation that led to Gon's death.
One great Neferpitou fanfiction is 'The Redemption of Neferpitou'. It shows an alternate storyline where Neferpitou tries to understand the concept of humanity more deeply. Another interesting one is 'Neferpitou's Journey'. It explores Neferpitou's growth and development in a world post - Chimera Ant arc. There's also 'Neferpitou and the Lost Soul' which delves into Neferpitou's encounter with a mysterious being that challenges its very nature.
Redemption is also a theme that pops up sometimes. Maybe Kite has a chance to redeem Neferpitou in some fanfics, or vice versa. It adds an interesting layer to their relationship as they might be able to change each other for the better. Another theme is the discovery of a shared purpose. They could find that they both have a goal that they can achieve together, which brings them closer and creates a strong bond in the fanfic world.
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.
A great Neferpitou fanfic often has a deep understanding of the character. It should capture Neferpitou's complex personality, including their loyalty to the King and their somewhat cruel nature. For example, a fanfic that delves into Neferpitou's thoughts and emotions during a battle would be interesting.
Well, it depends on the popularity of 'gon' and 'guila' in the fan community. Some lesser - known characters may not have a large number of fanfics, but it's still possible that someone has written a 'gon x guila fanfic'. You could start by looking at general fanfic websites and using the search function to see if there are any results.
The character of Neferpitou itself is very complex and mysterious. Fanfiction allows writers to explore its untapped potential. For example, in some fanfics, they can show Neferpitou's struggle between its Chimera Ant instincts and newfound emotions. Also, the world of Hunter x Hunter is vast and full of possibilities. Writers can create unique storylines for Neferpitou within this world, like sending it on quests to different continents or making it interact with other rare species.