Back of the head.

I'm really interested in how much character can be seen, or displayed, by viewing someone from the back. Portraits tend to focus on the front or side of someones face, frequently relying on their eyes, facial expression, and even the positioning of their hands to depict personality. But what about when you recognise someone from behind? Or think you do?
What about sitting behind someone and wondering what they do for a living? What kind of day they had?
So much can be conveyed from the way someone stands, sits, positions themselves within a space. The way they have their hair, the clothes they are wearing, all combine to form an idea of someone; an idea formed only from seeing the back of their head.
This is only the start of my exploration.