Mela didn’t answer. She waded into the attacking children, grabbing them and pulling them aside. But there were too many of them; they gathered around her and pushed her back, jeering.

Symat ran forward, fists clenched. ‘Back off.’

One of the girls faced him. She was shorter than he was, with a hard, cold face and her skin was waxy, almost translucent. She had drifted a long way from her core programming, he realised. ‘Whose child are you?’

‘I’m no child. I’m human.’

The girl jeered and pointed at Chem. ‘He thinks he’s human.’

Symat swung a hand at her face. His fingers passed through her pale flesh, scattering pixels. She flinched, shocked; that had hurt.

‘Do what I say,’ Symat said. ‘Leave my friends alone.’

The girl quickly recovered. ‘You can’t order us around. And you can’t hurt us.’

‘But we can hurt you,’ said a sly-faced boy.

‘Projections can’t hurt a human.’

‘Oh, yes, we can,’ said the boy. ‘We can come to you in the night. We can hide in walls, in your clothes, even in your body, human. You’ll never sleep again.’

The girl said, ‘You don’t have to be real to inflict pain. We’ve learned that in the years we’ve been out here. We will haunt you.’

Chem was crying. ‘Please, Symat, don’t let them hurt us.’

Symat stood, hesitant. The out-of-control Virtuals’ threats filled him with dread. And this wasn’t his fight; after all he hadn’t met Mela and the boys before yesterday. But Mela’s eyes were on him. His fists clenched again, he stepped forward. ‘Leave them alone or—’

The girl ran at him, burst through his chest, and pushed her hands through his skull so the insides of his eyeballs exploded with light. ‘Or what? What will you do, human?’

But the others didn’t follow her lead.

‘Kiri,’ the sly boy said. ‘Look at him.’

The girl turned, looked at Symat - and then stepped back, her mouth dropping.

Symat found himself surrounded by a circle of staring children. Even Mela and the boys were gazing at him wide-eyed. He saw that their protocol respect was weakening; some of them drifted up from the floor, and others tilted sideways, reaching impossible angles. They were like floating spectres, not children. They began to whisper, the strange, rapid speech he had heard from the boys in the night; he heard them mutter that strange name again - ‘the Guardians’.

And somehow Symat sensed the circle of scrutiny expanding beyond the limited circle of these children. After all, he reminded himself, these Virtuals were merely manifestations of the Mist, the cloud of artificial sentience in which all of Mars was immersed - and suddenly he was the centre of attention.

He had no idea what was happening, but he ought to make use of it. He raised his arms. ‘Get away!’