I was listening to a podcast called Writing Excuses and they were talking about writers pets and calling them TELLS. Things authors sometimes overuse- such as making a character blink too much. I notice I have characters swallow emotions and bit their lips and chew on fingernails. (A few of my bad habits.)
I was watching the last episode of one of my favorite shows, ONE TREE HILL, and I noticed a tell of the writer. Often, like almost every episode, two people will be having a conversation and when they end it one of them walks off. The person left standing there calls out their name, the other one turns back, and the dude standing there says something profound.
One of my idols screen writer Mark Schwahn