Her bedroom was small, but nicely decorated. A queen-sized bed faced the lone window and there was a couch against one wall. Charlotte had already warned me we’d be sharing the bed and I was cool with that. Provided she didn’t fart.

Most of the room was obviously dedicated to study. A huge desk took up the longest wall and on it were writing materials and a handful of old books, as well as a standalone tablet built into the wall. Above the tablet was a huge sign.

Winners embrace hard work. Losers see it as punishment. And that’s the difference. Underneath the words was the name Lou Holtz.

‘Who’s he?’ I asked Charlotte.

‘A twentieth-century sporting icon. He specialised in motivational quotes.’

I tried to look impressed, but I’m not sure I succeeded.

‘I really like your room,’ I said. And I did, too. Mine was about three times the size and my bed was much bigger as well, but her room was … cosy.

I lay down on the bed and Charlotte took the couch. I put my hands behind my head and examined another sign on the ceiling above me. The best way to predict your future is to create it. That, apparently, was by someone called Abraham Lincoln. What was it with signs in this household? I thought about asking Charlotte, but then decided to give it a pass.

‘I’m a bit worried about Aiden,’ I said.

‘Why?’

I explained how Aiden had been acting strange recently. That he spent more time on his own and much of that time he was staring into space. Thinking, apparently. I gave her a quick rundown of the strange conversation we’d had in his bedroom the night Charlotte stayed over. What I didn’t say was that I was concerned his focus no longer seemed to be exclusively on me, but rather in the private world of his own mind. True, I’d often complained that he was too attentive. Now I was bothered that he wasn’t attentive enough. Maybe I should do some of my own thinking, take a long, hard look at myself in the process.

‘Puberty,’ said Charlotte when I was done.

‘What?’

‘Puberty,’ she said again. ‘Don’t tell me you don’t know what puberty means, Ashleigh.’

Of course I knew what puberty meant. It was just that I’d never thought of applying it to me or anyone else. Maybe I’d just assumed Aiden and I would stay kids forever.

‘It’s the start of the process whereby both girls and boys prepare for parenthood, turning from kids to adults …’

‘Yeah, Charlotte, I know …’ But I might as well have been trying to stop a runaway truck with an outstretched hand.

‘It all starts with gonadotropin-releasing hormones, which the hypothalamus secretes at the start of puberty. When that GnRH hits the pituitary gland, a pea-sized organ in the brain, then – bang – the chain reaction starts.’