‘But I’m not a person. You have to see things from her perspective.’

I snorted. ‘No, I don’t. Anyway, she could still be sending someone.’

Aiden shook his head.

‘Same reason. Security guards are people. They would probably refuse to come into a place like this because it’s too dangerous and Mum wouldn’t ask them to come here because it could mean their death. Our friends here are hospitable, but they can be ruthless in defence of their land and their people.’

‘Then you’re safe here.’

‘Nope.’ Aiden picked up Z and put him on the table between us. The dog immediately sat and looked at my brother with eyes full of worship and a tongue that drooped and lolled.

‘I don’t understand.’

‘Here’s what I’d do in her place,’ said Aiden. ‘I’d produce some bots, small bots like insects. Maybe make them look exactly like insects. Send a swarm, all of them programmed to find me, bite me, put something into my system that would … well, would achieve what she wants to achieve.’

‘Could she do that?’

Aiden played with Z’s ear. ‘For someone who could make this, let alone make me, it would be very simple engineering.’

I felt like crying. It sounded hopeless.

‘So what are you going to do?’

‘I’m going to use my strengths. And I think I have many, probably more than I realise …’

I remembered what Mum had said about the necessity of killing my brother, how he would turn into something that could threaten the survival of the whole human race. And so I told him. I told him about Stephen Hawking and the idea that an AI using a deep neural network could produce ever more sophisticated and efficient versions of itself, to the point that no human could ever be an intellectual match. That such a being might condense millions of years of evolution into minutes, hours or seconds.

Aiden let me speak, nodding occasionally, but I could tell he was only partially listening. His mind was racing ahead, taking the information, processing it, analysing it and exploring all the possibilities it contained. Maybe I hadn’t told him anything he hadn’t already considered. After a while I dribbled to a stop. Aiden kept thinking, staring off into the distance, his hand still rubbing Z under his chin.

And then I started to worry. What had Mum said to me? We’d have no idea what he might turn into but it probably wouldn’t be the brother I’d always known. Was I even now watching Aiden leaving me?

He smiled.