This had to be Killua's top worry. Not so much the way he was raised as much as what his weakness was. The idea that some day he might abandon Gon, be unable to protect him when he needed to because he panicked when he found an opponent too strong. And Gon was stubborn and stupid and ran into things regardless of his likeliness to win. This was something that Killua thought about more often lately. That or that niggling fear Illumi had planted. That someday he would kill Gon. This was not as prominent because he just couldn't imagine that day. The other though...

"I'd protect them until I couldn't and then leave before my actions could hurt them." He said sounding more self assured than he felt.