'I understand your disappointment,' the Emperor said, amused. 'You and I have fought side by side for years. It is natural for you to feel this…' The Emperor's humour grew. Horus basked in it like he would the sunlight, even as it burned him. '…sibling rivalry. But I need him. We need him. He was made by me as you were. He is a brother for you, if you like. Brotherly competition is to be encouraged, because it will drive you on to greater efforts.'

The Emperor required Horus to look at Him, so Horus did.

'I know he is a little rough around the edges. Would you believe he challenged me to an eating contest?' The Emperor laughed softly. 'But I will tolerate no dissension between you. You are to cooperate. You must learn to make war together. I am relying on you to help me civilise him.'

'Impossible. He is a savage,' said Horus, unable to keep the word to himself any longer.

'I advise you not to underestimate him, Horus,' said the Emperor. 'He is woven from the same genetic threads that you are. He has conquered half a world a hundred times more savage than Cthonia. Had I not found him and taken him from his people, all of Fenris would have been his. The feat that would have been.' Once more, he smiled. 'Impressive. Do not underestimate him,' he repeated.

Horus' will buckled under the force of the Emperor's attention, but his misgivings would not retreat. He looked into his father's face. Few could do that. A poisonous worry gripped him that this new warrior would be able to do the same, that he was no longer unique. He was jealous, he realised. He would have to share the golden attentions of his father with another. The years they'd shared seemed reduced to an eye-blink. He thought they would last for all time, and just like that they were done. In that moment, everything changed forever.

'He could turn against you.' Horus suppressed a tremble in his voice.

'He will not,' said the Emperor with certainty. 'He will be as loyal as you are. His efforts will multiply yours, when he takes command of his Legion. Two of you, striding the heavens!' The Emperor was pleased. 'This is a propitious day.'

'You are going to give him a Legion?' said Horus. 'Forgive me, father, but is that wise?'

'I gave the gang lord of Cthonia his. It was your birthright, as it is his.'

Horus dropped his eyes. The Emperor radiated a sense of such wisdom. Once more, Horus was ashamed to have questioned Him.

'You are entitled to your misgivings, Horus,' said the Emperor. 'But you must make this work. He is only the first.'

I am the first, thought Horus before he could stop himself.