After I finished revising HOW TO MARRY A DUKE, I had one of those ah-hah moments. I realized that every scene in the book was about the premise. In retrospect, it seems obvious that every scene should promote the premise. But the plot of the story is the vehicle. Without character, readers have no reason to care.
Although I consciously chose a high-concept premise at the outset of writing HOW TO MARRY A DUKE, I never thought about plot and character as separate entities. Many authors claim their stories are either plot-driven or character-driven. That doesn't make sense to me. One cannot exist without the other. If, as I believe, conflict is the engine of the story, then plot makes up the external hurdle and the POV character's reaction forms the internal struggle. The two elements are closely intertwined. In order for the reader to become engaged, she must feel an emotional connection to the characters.
The plot or events in the story exist to force the characters out of their comfort zones. At the beginning of the story, the characters face a moment of decision. In THE WRITER'S JOURNEY, Christopher Vogler identifies this stage as The Call to Adventure. Resistance is common, but as in real life, external events sometimes force us to take unexpected journeys. Those journeys and the decisions we make along the way are often referred to as character-building. And so, fiction mirrors real life, albeit amplified to make the story compelling.
I don't think it matters whether the writer starts with premise or character; each presents challenges for the author. In my case, I had to invent a hero and heroine that fit the premise. I had to create their histories and give them story goals that made sense in terms of their pasts as well as their situations at the start of the story (Vogler identifies this stage as The Ordinary World). The goals we create for our characters spring from wants and needs. While the characters usually don't understand their deepest needs until late in the story, writers have to discover this in order to know what drives our characters to act and make decisions. When we know their deepest desires and fears, we can then throw obstacles at our characters in the form of external plot that challenge and gradually change them for the better.
Plot and character aren't mutually exclusive. One doesn't supersede the other. In the best of stories, plot and character are closely interwoven.