The rules for what should and shouldn’t anger people were not self-evident, as far as Milo Could see. He might once have cared about such things, but nothing as twee or pointless as smoking could rile him now. And yet there were things that seemed to anger them, his mother and her boyfriend, Arsenije. It was a question of tone and feeling, Milo thought. He could be saying something totally benign such as, ‘There weren’t a lot of people on the streets today,’ and this would be enough to set them off. Then, his mother’s hand would come down hard upon the side of his head, with a blow that would send him stumbling back. But in other, more normal circumstances, she might have said, ‘Oh, uh-huh,’ as long as he’d given Arsenije the required £20. Anger was, in short, an unpredictable emotion.