Here is my thumbnail cliche about plot and characters:
Characters should drive the plot.
Plot should impact the characters.
I dunno if that’s “right” according to all the academics or writing coaches out there. I didn’t get it from anywhere, it just seems right to me.
To expand a bit on this, what I mean is that the plot should feel like it develops naturally from the significant characters’ motivations, reactions and personalities. And the characters should change according to how the events unfolding around them (the plot) affect them.
This seems very straightforward to me. Whenever I find myself “plotting” my stories, the most important thing in my mind is whether the events I am planning are consistent with the characters I am creating, and then I ask myself what impact that particular event will have on the development of my characters.
It is one of the signs of an amateur writer, in my opinion, when things happen in the book that come out of left field, with no real rationale for why the character might even consider doing such a thing. And one of the best ways for me to lose interest in a story is for earth-shattering events to happen, and for the characters in the story to just keep on being the same people, as if nothing untoward has happened at all.