Human beings are unpredictable. We can snap, betraying decades of impeccable behavior and moral living. A devoted wife cheats with her son’s tennis coach. A respected policeman steals M&Ms from a convenience store. A shy boy kicks a cup from the hands of a homeless woman. Human frailty is an important part of humanity, and our characters. Our attempts to hide indiscretions often lead to unfathomable tragedy. Write a scene where your protagonist snaps. Show, don’t tell.