Every so often she stopped and talked to a man. They laughed, exchanged papers and then returned to their respective offices, which were located directly above/below one another. After a while I noticed a pattern forming. As the day progressed they both, independently of each other, got up and made their way to the other one's office. She took the stairs, he took the lift. She took the escalators, he took the stairs. This went on and on. But the longer they did it, the less their paths crossed. Until the very end of the day when they both left the building via the revolving door. For a short time their energies were channelled in the same direction, before peeling off and losing themselves in the crowd.
It struck me that it was rather like child's play in an adult world. Except on a see-saw you're working in tandom.