His father sat on his throne, fanned by slaves though the sun was sinking into the west. Dinner would follow, and at the thought, Xerxes looked for the little eunuch, Mishar, whose job it was to whisper about the Greeks each evening. He was there, dressed in a tunic of white silk, it looked like. New gold bands adorned his wrists and ankles, reflecting his rise in status.

Xerxes felt the eunuch’s gaze on him as he approached his father and dropped to one knee. Only the crown prince and heir could adopt the pose. That was his right, judged by every one of the servants and slaves around his father. They understood such things to a perfect nicety. Even kings would prostrate themselves before Darius, full-length on the marble, so that their breath made it cloud. But not the crown prince, not the young man who would follow in his steps and rule the world. In that way, his father gave him honour – and helped secure his succession.

Xerxes waited until his father nodded and then rose to approach. He took his father’s right hand in his and kissed him twice on each cheek, back and forth, before finally pressing his lips on those of Darius. There was a sweetness on his father’s breath that troubled him, a scent of green datura.

‘Are you in pain still, father?’ he said.

The king’s eyes were bloodshot, he saw, with a faint yellow tinge to the skin. Xerxes felt a pang of something like panic. He was not ready for this, not yet! He had ridden a thousand miles to Persepolis when his spies in court had reported the king ailing. In all the days of hard galloping, he had not considered the reality that lay behind his father growing ill. Men died. Xerxes knew that as well as anyone. He had witnessed executions by the thousand, seen men, women and children killed in battle, or simply for sport. There were always more, given the way they bred. Yet his father had been the rock on which the empire stood, unbreakable, eternal.

It shocked Xerxes to understand the man had lost weight beneath his robes and panelled coat, to see the way his throat had grown thin, so that lines of flesh stood out like wires. Darius was sixty-two years old. When Xerxes had left two years before to tour the kingdoms of the empire, he had not understood it was to prepare them for his rise to the throne.

‘It is good to see you, my son,’ Darius said. He smiled.

If kings and satraps might have flinched at that expression, Xerxes saw only affection. He kept his father’s hand in his and pressed it. He felt the knuckles shift against one another, where once there had been muscle to draw the great bow or hold a sword. Xerxes found tears in his eyes and let them spill without shame. It was not so strange. Many men wept when they met the Great King.