The writers who create the best characters tend to know them really well--not just the bits that are revealed in the novel or screenplay.
Prime example: the late advertising master, John Webster. In the current issue of Creative Review Patrick Collister shares a story about the time Webster created a Sony ad featuring a robot whose wife was a vaccuum cleaner.
In one scene the robot and the vaccuum cleaner were sitting together on a sofa. Collister said, "Before the shot, I watched John taking out chocolates from a box and unwrapping them and then dropping the wrappers around where the feet of the vaccuum cleaner would be.
I said to him, 'John, it's not going to be in shot.'
'It doesn't matter,' he said, 'this is what she does when she watches telly, she eats chocolate.'
I thought that was so revealing."
Webster also created the Smash Martians, Monkey, the Honey Monster, and Hofmeister Bear. Probably he knew what they did when they watched television, too.
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