I became a writer the day my mother told me to put down on paper what was going on in my head. It has lead me to pursue one of the best jobs in the world: making stuff up. It's always a special experience when you reach into that well of ideas, though some ideas may be darker than others.
Speaking of where ideas come from, I couldn't tell you even if I wanted to. It would be like asking "where do you get your ideas for your dreams". We all have more ideas than we will ever know what to do with. They're just "there". Writers are simply people who bother putting it down on a page.
My view on what a story should do, is that it ought to provide the reader with an emotional experience, whether it be joy and pleasure, or fear and dread. The best story writers know how to make use of the full emotional spectrum.