Great question! When I sold The Naturals, I sold it in a two-book deal, so although I had some vague ideas for later books and planted a few things I could harken back to if I got to write more, I wasn’t counting on for sure getting to write Books 3 and 4. So for Book 1, Nightshade was meant as a red herring, but even as I wrote it I thought “Who is this guy and why is he so interested in these kids?” and made a mental note to figure that out as the series went along.
Long story short: I didn...