‘Accept what you see,’ said the Lion. ‘Nothing more of significance will occur on Davin. All that matters has already happened.’

‘Everything has already happened,’ Curze snarled. ‘Not just here. Everything is written. Nothing can change.’

Sanguinius stopped his pacing. ‘You are wrong, Konrad,’ he said. ‘I know the future can change.’

Curze looked at him with genuine unease.

The Angel approached the south end of the altar. He rapped it with his fist. ‘This was a fulcrum,’ he said. ‘Fate pivoted here. Horus fell, but why did he fall? Something turned him, but it did not transform him. He is still Horus. When he betrayed my Legion and sent us to the trap of Signus Prime, he fooled me because he was our brother. He is not a changeling. He embraced his descent into darkness. So however hard he was pushed, tempted or manipulated, he must still have made a choice. There was a decision.’ He looked at the Lion. ‘You faced a decision too. You might have killed me. Was it fated that you did not?’

‘Of course it was,’ said Curze. ‘You disappoint me, Sanguinius. I thought you were beyond trying to wriggle free of the hook. I thought inevitability was why you brought me here. You and I do not die on Davin.’

‘Don’t we? Is there no chance that we might have? I wonder. Remember how near to death you came on Macragge, Konrad. You felt certainty slip away then. Destiny was on a pivot, and it almost turned.’ Sanguinius turned to the Lion again, pushing his brother. He felt the charge in the air again, and it grew stronger as he moved closer to revelation. ‘How close did you come to giving the order for the bombardment?’

‘Close,’ the Lion said. He hesitated, then continued, ‘My reason was clouded.’

‘Yet you did not give the command,’ Sanguinius said. ‘Where is the victory of Chaos, Konrad? The universe acted to spare us.’

Guilliman said, ‘I faced a decision too.’

‘A fateful one?’ Sanguinius asked.

‘Yes.’

‘Do you see the pattern?’ Sanguinius realised he was breathing faster. An enormous possibility was opening up before him. He would articulate it this time. He would make it real. ‘The Davin ­System is a fulcrum of destiny. Brothers, you chose well. Horus fell, but you remain standing. We have been brought here to be tempted, just as Horus was.’

‘If this is so, then you too must face a decision,’ said the Lion. ‘What is it?’

‘I perceive it imperfectly, but I encountered it on Pyrrhan.’ He paused. ‘Konrad knows when and how he will die. I, too, know the moment of my death.’

Guilliman looked stricken. The Lion’s face darkened with surprise and anger.