You'll try and play down what you think he thinks you mean to him, but you know he needs you, as you him, because you have watched him when he didn't know you were watching and have have felt the tension unspool around him when he sees you. Whoever you are, and wherever you were, and whatever it was you did it with - the result is enough to shock a passerby from the unmistakable, uncensored evidence of calmness in his eye.