Here is a perfect example of what you do as a puppeteer when your puppet has no lines or doesn’t play a huge role in a scene. A wise puppeteer once said to me that in these situations have your puppet react to what is being said, don’t just have your character sit still, movement is life. However, realize that less is more sometimes and that “overacting” can also take away from a scene. It is a fine line and takes tons of practice!
This video is a perfect example of this “lesson”. Watch Bert closely. The scene is based on what Ernie is saying but includes Bert to back Ernie’s emotions and add (as usual) a comedic element. Also watch how Ernie and Bert relay their emotions to the audience. Take note to their eyeline, the position of their head and the body language they implement to each emotion. A simple skit but very well executed.