Ha ha...I don't even know myself when I start a story how it's going to turn out - I don't plot out stories - never have - sometimes people suggest ideas if I serialize a novel and I honestly take their ideas into account, but I do have a feel for the characters and the plot grows out of them. It's called organic development of plot - first you have a character and then you ask yourself, 'What would this person do?" Even back in high school my English Lit teacher used to admonish us about the soap opera preoccupation about getting hung up on plot and wondering what happens next. He'd tell us we'd have to get beyond that, and for better or worse, I've tried to do that. As for the reverse, I know Dickens was influenced by Wilkie Colins who wrote The Moonstone, and he wanted to plot a novel similar to that, so he used that method to write Great Expectations. I guess it's whatever works for you and the characters.