Creating convincing characters is an important part of novel writing. But which comes first? Characters or plot?
If I am writing a one-off novel or the first of a series I will create the plot first. Then I will design the characters to fit the demands of that plot. I find that much the easiest way to do it.
When I come to write the second novel in a series I have no option but to begin with ready-made characters from the first book. Now I have to work the plot around those characters, and that's not so easy. I may want them to behave in a certain way in order to make the plot work, but the way I originally designed those people may make that behavior impossible. They must behave according to the character traits I gave them.
That's the problem I had to work on when I wrote the plot for the sequel to In Foreign Fields. My characters were fully formed from the first story and the plot had to accommodate them.
So my plot-line for this second book started out with two main constraints. The first was the ready-made characters. The second constraint was what actually happened back in October 1914.
All of this is part of the reason why I use a story development system.