Character-based plotting workout …
1) Take a secondary character from any novel you like. Imagine that the events of the novel never happened to them. What is the biggest challenge imaginable for that character? What would be required to give them an emotional response so big that it would carry them, and the reader, through the challenge?
2) Using the character and situation you just imagined, create a sequence of 3 major events that would advance or hinder their progress in overcoming the challenge?