Ideally the photographer aims to ensure the person being photographed feels comfortable and there isn’t too much self-consciousness. If the subject’s mind is elsewhere, it’s a good idea to
get the model into the present moment; focused on how they are looking in the
camera, where they are, the photographer, what the photographer is saying, their
positioning, and the interaction itself. You don’t want the person being photographed to be thinking they would like to be elsewhere, daydreaming (even if it is about something positive), or in their head worrying about the future. 

The photographer guides their subject toward a mood, vibe, feeling that they both want portrayed to the outside world. Ultimately, the connection as a photographer that you build with
the person being photographed is done in a way where both are comfortable-which
depends on the personalities of both people.