[ Despite the realization dawning on his face, it only manages to get darker. She's totally right. In the heat of the moment, the other man's involvement had gone very out-of-sight-out-of-mind, but he wasn't taken care of, he was just... somewhere else. They've only helped themselves out here. And maybe ruined a couple other days down the street. ]

He's gonna run into a helpless house and kill everyone, or a house like ours and kill himself... So if we were real good people, we'd run back out and dust him too?

[ He sounds a little incredulous, probably because it actually sounds like the smartest hypothetical action to take. Smart thing and murder are two wires that just don't connect in his head. And the fact is starting to make it ache. ]

Where's that stop though? What if he was just... having a bad day like you almost did? And if someone goes on a mercy killing spree, we could find the cure tomorrow. If we sit on our hands while they keep attacking everyone, we might not find it for weeks.

[ Running his hands through his hair doesn't do much for the nonexistent cool he's about to lose. ]

We can't lock them all up, we can't let them all loose, we can't kill everyone, there's-- There's not a right answer for any of this...