When Killua looks at Gons condition at the end you can feel his heart breaking😭 to see him in such a state is so sad, but he has the more mental strength to handle it & holds his own to save Gon. When in Gons case he couldn't handle seeing Kites condition & knowing of possible death. I love the contrasts between these two yet how they are best buds. They balance each other out.
not gonna lie, the way Gon treated Killua the end wasn't cool though, I loved then together and it broke my heart to see Gon treat Killua that way, That's why they split paths. Got really only saw Killua as a teammate and was in it to see Ging while Killua truly cared about Gon.