I don't agree that they're "not thinking of the consequences of what they're proposing" -- especially since they ACTUALLY START DOING IT very soon thereafter.
That's the action, not the consequences. I don't think it *really* dawns on Mrs. Lovett what they're really getting away with until it's clear that Toby has figured it out. (Obviously she knows, but she isn't really taking it seriously until then,) And of course Todd doesn't get his "epiphany" (so to speak) until he finds his wife dead, and it's too late to revive her. And of course, that Lovett was hiding Lucy's identity from him. For Todd, especially, the consequences aren't that people will die, it's that someone he loves will die. |