The Roman emperor Domitian began life as a spare. At the end of the 1st century CE, while his brother Titus was the heir to their father Vespasian, the younger boy’s ‘sense of resentment and frustration had festered’, writes Tom Holland. ‘Rather than stay in Rome, where his lack of meaningful responsibility was inevitably felt as something raw’, Domitian moved away with a wife whom his family disliked, ‘doomed forever to be a supernumerary’, paranoid, attracting gossip, avoiding any company in which ‘innocent mention of baldness’ might be viewed as ‘mockery of his own receding hairline’.