‘I’ve been very lucky,’ he said. ‘That limiter Mum installed in my brain. It was obviously damaged in the kayak accident. When it wasn’t working properly, I started to have … well, such strange thoughts, Ash. You remember. You were worried I was turning weird. But in fact they were just my intellectual baby steps. I saw things clearly. I saw … connections. I felt there was no problem I couldn’t solve. But that scared me and I tried to shut it down. Now I know that was a mistake.’

‘Can I ask you something?’

‘Of course.’

‘In the park I told you that you’re not human. You didn’t break down, you didn’t tell me I was lying, you didn’t even argue. Instead, you walked away for an hour, came back and it was like you’d accepted everything. That’s just … just …’

‘Not a normal human reaction?’

‘Exactly.’ Aiden smiled and then I understood what he was getting at. ‘Oh, I see.’

‘You said I was away for an hour, Ashleigh. For me it felt like days, weeks even. Something is happening with time.’ He tapped his head. ‘Up here. I’m thinking and feeling quicker and quicker. Having this conversation … well, it’s kind of like wading through mud. I speak a sentence, but a million others go through my head in the time it takes me to say it. It’s scary and amazing all at the same time.’

‘You’re doing what Mum said you’d do. You’re evolving into … something else.’

Aiden reached across the table and took my hand.

‘I said before that I tried to shut things down, banish the ideas I was getting, become … more normal, I suppose. I think the news you gave me wasn’t really news at all, Ash. I think I knew the truth, somewhere in my … what’s the right expression? Memories? Algorithm pathways? And the knowledge that I am a machine has given me permission to behave like a machine. I’m discovering stuff about myself all the time. It’s like before I was operating at one thousandth of one per cent of my capacity.’ He laughed. ‘Charlotte would be impressed.’

‘I don’t want you to change into something else,’ I said. ‘I want you to stay my brother.’ I could feel tears gathering. I didn’t want to cry, not on what was probably going to be our last day together for a long time. Maybe forever. Aiden squeezed my hand harder.

‘I think whatever I change into, I will always be your brother, Ash.’

‘You think. You don’t know.’

‘No,’ he said. ‘I don’t know.’