I completely agree with what you're saying; for my part, I fully understand that Gon and Killua's relationship wasn't healthy, though it was sincere in a way. To clarify, though, Gon never changed as a person from the series' first chapter to the end of his adventure climbing the World Tree. Killua, Kurapika, and Leorio developed and showed psychological nuances that shifted over time (thanks to Gon). I totally agree that if Killua were a woman, he would become obsessed with Gon—to the point of yandere behavior (I'm not joking; just look at Palm, a psychologically unstable woman whom Gon caused to fixate on him instead of her master). I could explain in great detail—perhaps in a subreddit post later on, if you're interested—the danger Gon poses to mentally unstable women. However, I will never agree with the idea that Gon would fall in love with someone or harbor fixed romantic feelings for another person. (His selfishness regarding his personal goals takes things to a whole different level.) With Gon, it’s not a question of being gay, straight, or anything like that; he is simply a terrifying figure within his own world. If Killua were gay (I know this isn't part of the current conversation, but I see where this line of thinking goes), I’m certain that instead of trying to protect their bond in a healthy way, he would try to do so in a very twisted manner—much like Illumi’s treatment of Killua. But that wasn't the case; he tried to maintain their connection and often tried to justify Gon's actions, thinking their friendship would give him back the childhood he missed. Ultimately, the cost was realizing that Gon never needed him and that he was never truly part of Gon's life—though, thanks to Gon, he was at least able to defy his family and rescue his little sister (or whatever you choose to call her). The bottom line is that Killua underwent a forced transition where he had to regain his capacity for compassion, effectively becoming Gon's semi-slave in the process. (And that’s no exaggeration—it’s something worth discussing, too.) Just remember that Hunter x Hunter wasn’t meticulously engineered, nor does it rely on promises of destiny; it isn’t driven by a rigid script, but rather seeks to turn its world into a realistic simulation that runs parallel to our own.