Really, that was the coincidence.
Mark was about to take a taxi when he saw Robert going out of the building, He waved at him and first Robert hadn’t recognised him, thinking that that was some fan - he just waved back and turned away and went down the street, willing to get away as soon as possible. No, Robert loved his fans - but for them how could he become that called-for as he was now? - but he didn’t feel like doing that ordinary things that celebrities do that evening. But when Mark hailed him that made the things different. The smile lit up on his face as he turned back to go toward him.