My ideas, after the first idea—often situational—come out of character. So I had an idea that began my novel ALIEN INVASION & OTHER INCONVENIENCES. I wanted to write an alien invasion novel, but the situation I saw was a story about the survivors. So I made the invasion take ten seconds. A radical departure from most alien movies and stories. And then I started thinking about European countries that arrived in places where native populations were primitive. For example, Cortez landed in Mexico with something like 150 men and a couple of cannons. He conquered the Aztec empire—over a million people—because he had guns. What must it have been like to the indigenous population? At first they thought the Spaniards were gods.
So, let’s say we’re on the loosing end this time. The invasion takes ten seconds. That’s how I started my novel. “It takes less time for them to conquer the earth than it takes for me to brush my teeth.” The second line just came to me and it creates tone. “That’s pretty disappointing.” Is tone an idea? I don’t think of it that way but my tendency is to write serious humor stories, so this tone fits.
Okay, so that’s the start of the my novel. But then what? If that’s all I’ve got, then I’ve really just got a few lines.
Ideas have to grow out of that first idea. Or as Patrick _Ness said, if you prefer to see it this way, an idea has to attract others. So I have my main character and he survives the initial invasion. He becomes a slave. But what are the particulars of this? These big ideas are good for situations and setting up story but we need details to develop the story. So for that I’m going to my character. I need to start figuring out what he wants and desires to help find my way to the story.
What does someone who has lost his freedom want? One thing, of course, is he wants that freedom back. But the situation in the beginning is dire. The world has been taken and people killed and the alien masters threaten at every turn. So freedom isn’t really an option yet. Revenge? Not possible. Survival? That’s the first thing. He wants to survive and he wants to, even if he doesn’t know it, somehow start the process of rebuilding his life. To do that he needs friends, allies.
Okay, so I didn’t think about all this as I was writing. I’m analyzing it now. When I’m writing I’m just thinking about character and situation and pushing that character to develop to create new situations which in turn create scenes. But this is the way I begin to build a story.