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.
Itadori did indeed die in the manga. His death had a significant impact on the story and the other characters. It was a turning point that led to many new developments in the plot.
Itadori is quite powerful in the manga. His strength lies not only in his physical abilities but also in his determination and the unique powers he acquires along the way. He's able to face off against formidable opponents and come out on top more often than not.
Well, Itadori's journey in the manga has been full of surprises. He's had to deal with curses, make difficult choices, and his relationships with other characters have evolved in complex ways. There have also been moments of great personal sacrifice and growth for him.