Vash doesn't flinch at the snap. Instead, he is visibly relieved.

"From where I'm standing..." softly, "you have been trying to get him to kill everyone since..." His right hand rubs the left shoulder, above the cut. "For a very long time. Sorry."

A small nod.

"Then I'll stay out of reach of any groups of people - humans - until I know if they are Terrans or not, and even if not, I'll only approach with caution." This part he knows he needs to specify, because if Knives put this much energy in explaining to him, it matters, and he had better pay attention. "And... would you be willing to tell me? How... you see the world now."

Because Knives is still his brother. And he wants to know, and cares. And loves.