It’s one thing to write "John was feeling alone, half in the world of his youth and in transition to the world of an adult. It’s another to depend on graphics to get the point across.
There are some obvious tools available in simple facial expressions such as a smile, a frown, tears, wide-eyes and clenched teeth. All these are emotional devices based on how we communicate without words. Slumped shoulders may indicate despair or feeling low. Porcellino has drawn characters that are easily followed in their moods by their expressions and a few of the more standard elements used in comic strip stories. The image of the heart indicates John’s feelings for Kristi. There are differences in mood and attitude indicated by open or closed eyes. John’s eyes are closed when he is talking to his parents, indicating that he is effectively tuning them out.
Panels without dialogue normally indicate a transition of scene or break in time. Porcellino also uses them as a pause for the reader to consider a change in attitude or to emphasize a depth of mood (many frames, perhaps the character moving away from the reader/viewer).
Porcellino also seems to use closeups and longviews to enhance the loneliness that John feels as he wonders about how he fits in with others. He pans out to a city, a beach, a large dark area wherein John appears smaller and smaller. All of these are tools for the graphic writer.