Finding the heartbeat

When does life begin? For a novel, not at conception. It's when a character steps in and says, I'll take it from here. When that happens it's like an engine starting up, and sometimes the car starts driving itself. I don't know exactly what makes this happen -- different things drive fictional characters, just like people. A bit of freewriting, some forced dialogue, a change of scenery (akin to a change in perspective) can sometimes do it. A question mulled during a long walk -- what would she do now? How would she react? Ask her long enough and she'll start talking to you.