I stood at the bay window and pulled back the curtain, my hand making the length of fabric tremble. It was pitch-black out there, with thick clouds covering the stars and the moon, but the street light showed an empty driveway.

He had left. His keys were on the mat, posted back through the letterbox. I pictured him parking round the corner and creeping back to kidnap me.

I turned and screamed.

‘Sorry,’ said my sister, standing blinking in her blue dressing gown, confused. She was holding the envelope that had Sasha written on the front in Dad’s best handwriting (which was still bad, even when he was trying; he was a doctor after all). ‘What’s happening, Mermaid? Why has Dad written me a letter?’ She shook her head. ‘Actually I don’t need to open it. He’s telling me off again about my irresponsible behaviour. Reminding me that I’ll never be a doctor. I’m going to put it straight in the bin.’

I hugged her as tightly as I could. She resisted for a moment and then gave in and hugged me back. I didn’t cry. I didn’t cry. She smelled of Sasha and sleep.

‘What’s up?’ she said. ‘What’s he done?’

‘He’s gone,’ I said into her hair (Sasha was four years older than me and maybe four inches shorter too). ‘It might be one of his mind games, but he said he was leaving. He had a bag. The car’s gone. He …’ I didn’t want to tell her this part, but I knew I had to. ‘This next bit’s awful, OK?’

‘Tell me.’

Sasha followed me into the kitchen. I put the kettle on and got out two mugs.

‘He woke me up about an hour ago. Maybe more? Before five. He was all showered and ready. He said I had to get up and go with him.’ My voice cracked, but I carried on.

‘He said it was a fresh start and he’d buy me a MacBook. He said you didn’t need us. When I told him I wasn’t going, he went all cold and stormed off. And now I think he’s actually gone. Look. He put his keys through the letterbox. He left me this.’ I showed her the note. At this point the tears started coming. ‘Am I going to have to go into foster care, Sasha? Am I?’

That part was just beginning to sink in. I couldn’t do that. I couldn’t.

‘Fuck,’ she said. ‘Oh God, Ariel. No, you’re not. Of course you’re not. You’re staying here with me. I’m sure they won’t take you away.’

When she opened her letter, we found it was more coherent than the note he’d scrawled to me. Coherent but psychotic.