We’ve all heard the rule of threes. That is, bad things come in three. Accident, illness and even death show up in our lives and thanks to bias, people tend to notice when they occur in sets of three.
So should your characters.
As an exercise: Take some of the minor or side characters from your current work in progress and write a scene where they discuss what sort of tragedies they’re experiencing in threes. Make sure to include things that are happening outside your main story.
Bonus: Use the same exercise as above but write about the positive things that are occurring in threes to your characters.