When I was studying theatre in college, we once had a visiting instructor who facilitated an entire workshop on mask play.
It was really fascinating because he used various masks – neutral, masks of agony, happiness, etc. and had us play various scenes wearing these masks. It was a great exercise for us to act beyond the mask (or in spite of it) and use our entire bodies, not just our faces. It was also a great exercise in listening, because the other actor in the scene was behind a happy face or a sad face or a neutral face and we had to really listen for tone and inferences and watch the actor’s body language.
When I have trouble trying to write a scene, I try to remember that mask exercise. What “mask” is that character showing to everyone else – or to everyone else but one person? What sort of body language would they have that might betray that mask? What sort of lines might give us a peek behind it?
Stripping that mask away – or slamming it firmly into place – can really add tension or insight or maybe even both. It’s a good writing exercise, even if the mask is made of words instead of papier mâché.