killing off central characters -- but what if they die first?

My stories always go in directions i did not expect or plan sometimes, and i get to decide if that's where they were supposed to go or not. This is the excitement and burden of writing off a minimal outline. I have a friend who is a writer who was saying that his friend who is also a writer had a central character who stepped out of car in the middle of the book and got run over on the freeway. His character just offed himself without his permission! The author apparently was really upset he lost his protagonist, but he went on with the story because he believed that's what had to happen. Now isn't that bizarre? It floored me! I mean, I don't see how i could have Ame (my star in 'Grand Theft Life' and 'Maze') just fall in a hole one day, against my wishes, and force me to write the story around her? that seems ludicrous! but its funny to think about anyway.  -K