What are your favorite techniques for brainstorming illustrations?
Writing what I want to say about how the characters feel then coming up with concrete examples? Doesn’t sound terribly objective though.
I might make a list of anything, even bad ideas.
Are you referring to the plot sequence report? If so, then I ask, “I wonder what (character name) is doing right now?” for every relevant character and see if there could be any connection to that illustration. Kind of like, “I wonder what Arsenio is doing right now?”
If every single possibility feels forced, then invent a character–even a bit part–to interact with someone already introduced.