This is one of the easier prompts that can be written about when analysing and deconstructing images of people. We're almost all aware of how people communicate their feelings through their facial expressions and body language, so the way that we incorporate this aspect of making images has a significant impact on the way that the image is perceived. Similarly it's probably one of the most productive options when using the prompts to deconstruct and analyse images.
When doing this we can't discount the surrounding factors - backgrounds, props, clothing, body language, semiotics, location, relationships and accompanying text. All of this is rich in potential meaning allowing you write and comment about the images. What do the expressions or body language tell us about the person and their environment, how has the photographer used this aspect of their photography? Is it intentional, natural or constructed? How significant is the facial expression or body language, is it subtle or is it a massive part of the image narrative?