During my first weeks working with a new client, he got upset for no apparent reason and went to his bedroom and slammed the door. He came back down a few minutes later with his hood pulled over his head and would not talk to me. I asked what was wrong and tried to converse with him for over an hour but he just ignored me.
A little later on, one of my colleagues explained to me that this particular client behaved in this way to gain attention and the best thing to do was to ignore him until he had calmed down. I put this into practice the next time he did this and within ten minutes, and after realising I wasn’t giving him any attention, his hood came down and he apologised and started chatting to me.