Humphrey Bogart & Lauren Bacall in To Have and Have Not (1944, dir. Howard Hawks) (via)
Q. How did the Bacall character in To Have and Have Not develop?
Howard Hawks: We discovered that she was a little girl who,  when she became insolent, became rather attractive. That was the only  way you noticed her, because she could do it with a grin. So I said to  Bogey, “We are going to try an interesting thing. You are about the most  insolent man on the screen and I’m going to make a girl a little more  insolent than you are.”
“Well,” he said, “you’re going to have a fat time doing that.” And  I said, “No, I’ve got a great advantage because I’m the director. I’ll  tell you just one thing: she’s going to walk out on you in every scene.”  So as every scene ended, she walked out on him. It was a sex  antagonism, that’s what it was, and it made the scenes easy.
-excerpted from Howard Hawks: Interviews

Humphrey Bogart & Lauren Bacall in To Have and Have Not (1944, dir. Howard Hawks) (via)

Q. How did the Bacall character in To Have and Have Not develop?

Howard Hawks: We discovered that she was a little girl who, when she became insolent, became rather attractive. That was the only way you noticed her, because she could do it with a grin. So I said to Bogey, “We are going to try an interesting thing. You are about the most insolent man on the screen and I’m going to make a girl a little more insolent than you are.”

“Well,” he said, “you’re going to have a fat time doing that.” And I said, “No, I’ve got a great advantage because I’m the director. I’ll tell you just one thing: she’s going to walk out on you in every scene.” So as every scene ended, she walked out on him. It was a sex antagonism, that’s what it was, and it made the scenes easy.

-excerpted from Howard Hawks: Interviews