Chekhov's Gun and the Key to Character
Who knew this old chestnut unlocked character?
You already know about Chekhov’s Gun: a gun on the wall at the beginning of a story must be fired by the end. Otherwise it’s a needless element in the story. We don't all need a gun, per se, but we want to look at what the metaphorical gun might be in your book. The tension of anticipating a metaphorical shot can carry you through the slower, middle parts of the story.
In the words of Hamilton via Lin Manuel Miranda, do not throw away your shot. I’m sorry, I just couldn’t help it. Let’s forget that happened and move on to unleashing your characters, shall we?