The saying, "Butter wouldn't melt in your mouth" refers to someone being insincere or overly coy. It can mean that a person appears so cool that butter would not melt in that persons mouth if out there. It is quite a common saying down our way.
Maybe Laura was more pleased about the deal than Ben Kilpatrick was......but as you say. who knows? That wild bunch were great at making up their own rules. 😊
Howdy again Trudee! Ok, I get that saying about the melting butter now. I couldn't tell if it was a compliment to the way he looked in that photo or not. But yes, he was very unfeeling and enjoyed shooting people as demonstrated in that last train robbery that they blamed on Butch. But he had a long history of killing and murdering people before he got with the Wild Bunch.
I think Ben Kilpatrick, the Tall Texan, like Laura, or at least it was convenient for them, because they were still together a couple years later when they were arrested together for money laundering. She looks rough in that mug shot but probably looked pretty nice when she smiled but I think that's the only photo we have of her.
Anyway I'm babbling! lol...thanks for the explanation.