A look of concern crosses Billy's face at that last part. It's a very interesting tale, and he listens with rapt attention, but...born to eradicate? How intimidating.

Billy considers this. As far as he knows, Kaworu hasn't done anything to eradicate all the humans living around Exsilium. He's only known Kaworu to consider them interesting specimens, and he does spend an awful lot of time giving them advice. It could be false advice, meant to steer them on a dangerous path, or...what does his heart seem to say?

"You said you were born to kill us. You never said you were doing it, or intended to, or wanted to." There's a faint defensive edge, but his trust isn't erased here. He simply wonders.