‘Don’t get any ideas,’ a voice said from just behind his shoulder.

‘Good evening, noble Laberius,’ Hadrian replied, as the former consul came alongside. They kissed on the cheek in greeting and smiled with everything apart from their eyes. Until now Laberius Maximus had been near the rear of the little procession, talking with men of his own age.

‘We do not want any more awkwardness, do we?’ Laberius gripped Hadrian’s right arm just above the elbow, a gesture that always annoyed him. ‘Good, good,’ he went on. ‘Youthful indiscretion is one thing, but you are a praetor now.’

Hadrian smiled. Just before the first campaign in Dacia he had taken one of the imperial boys as a lover. It was not rape, or even coercion beyond the fact that one was a slave and one was an aristocrat. He had wooed the boy, given him presents as an older man should, and been kind. Yet Trajan’s rage had astounded him and for a while he feared that he might be sent home in disgrace, favour forever denied. Men closer to the emperor had placated him, mature men with good military records like Laberius, the sort of men Trajan liked and trusted, and in the end Hadrian had been forgiven, at least publicly. There was no need for reminders, for he was not a man to make the same mistake twice, but it had put him under obligation to Laberius and the rest.

The whole business was a nonsense and Trajan’s anger a mystery. The emperor must have known that gossip throughout the empire, let alone among the aristocracy, was amused by his fondness for having lots of pretty boys in his household, just as they were by his habit of drinking heavily when he was the host at a dinner. Hadrian had nursed plenty of merciless hangovers as a result, for like most guests he felt obliged to match their leader. Yet he did not know for certain that Trajan had ever used any of the boys in that way, whether casually as slaves or with kindness. It was so hard to tell. Maybe this was all part of play-acting the tough soldier, and, realising his own appetites, the emperor rigidly exercised self-control, denying himself the slightest concession to human frailty and vice. Then again, maybe he was very, very discreet. Either way, the Roman aristocracy would approve. Excesses denied were admirable, indulgences concealed were pardonable, as long as the secret never escaped for such was the hypocrisy of the senatorial class. Trajan had never done anything unwise or acted badly while drunk, so that was also no weakness or flaw, and the same attitude stretched to the boys at court. If ever anything dishonourable happened, then no one saw it.

Hadrian did not know the truth, and after all these years could not claim to understand Trajan. That, indeed, was the root of the whole problem. Hadrian’s father was the emperor’s cousin, and when both his parents died, Trajan had become Hadrian’s guardian, back in the days when he was no more than a prominent senator. He had been efficient, stern and distant, and had softened only a little in more recent years.