I left Troy in his bath and went to the kitchen, where Brendan was standing amid the builders' wreckage microwaving a jug of milk for Troy 's chocolate. It was a clumsy process because he could only use his unbandaged hand.

'I got Marcia's message on your answering machine. Clearly she doesn't know you've moved out,' he said. The microwave bleeped and he took the jug out, stirred in the cocoa and sugar, and whisked it till it frothed. 'There.' He took a little sip and added more sugar. 'So I thought I should go and look.'

'Where was he?'

'Down by the derelict warehouses. I don't know why I went there – I just had a feeling he was there, like an instinct. I knew. I think some people have that gift, don't you?'

I shrugged.

'Who knows what might have happened if I hadn't been there. I think I was meant to save him. It was fate. And so I've made a decision.' He poured the drink into a mug. I'm going to put off looking for a job until Troy 's all right. Troy will be my job.'

'Oh no,' I said, 'I don't think that's a very good idea. Not at all. In fact, if you ask me…'

'I'm not,' he said calmly.

'Well, I'm going to tell you anyway. Troy doesn't need you. The very opposite. What Troy needs, apart from anything else, is you out of his…'

'I'll take him his chocolate,' Brendan cut in. 'You don't really need to stay if you're busy.'

'I'll wait,' I said furiously. 'I'm not leaving him.'

'As you like,' he said.

'I thought you were getting better. I thought things were getting back to normal at last.' My mother was pacing the room in an agitated fashion. Her hair was half unloosed from its bun and hanging down in strands over her face. She was wearing a jumper back-to-front.

'What does "better" mean, exactly?' asked Troy. 'And what's normal? No one's normal.'

He was sitting on the same sofa I'd found him on the previous night, in the same slumped position, as if there weren't a bone in his body.

'Oh, for God's sake,' snapped my mother.

'Calm down, love,' said my father, who was standing with his back to the window. He'd come home early from Sheffield and was still wearing his suit. He hadn't shaved, though, and the knot of his tie was pulled loose. It wasn't exactly a total psychological collapse, but it gave him an odd, raffish look.

'Calm down? Is that all you've got to say? Every time something goes wrong, that's your advice. Why don't you say you'll make us all a nice cup of tea?'

'Marcia…'

'I want someone else to take charge here, not always me.'

I glanced across at Troy. The sun was shining through the window on to his silky hair, and he seemed quite tranquil. He felt my eyes on him and looked up, raised his eyebrows and gave a little smile.

'Tea would be nice, actually,' he said. 'And I'm quite hungry. I haven't had anything to eat all day.'

I stood up.

'I'll get us all something in a minute,' I said. 'Toasted cheese sandwiches?'

'Thank God Brendan was here,' said Mum fervently. I flinched. I'd been there too, hadn't I? 'If he hadn't found him…'

'I'm in the same room, Mum,' said Troy. 'You can talk to me.'

'What have I done wrong?'

'What's it got to do with you?'

'Exactly,' said my father. 'We're not going to get anywhere if this becomes about your feelings of guilt. This is about Troy.'

My mother opened her mouth to say something, then changed her mind. She sat down on the sofa and took Troy 's hand.

'I know,' she said. 'I was so worried. I kept thinking…' She stopped.

'I wasn't going to kill myself or anything,' said Troy.

'So what were you up to?' asked Dad. 'Skipping lessons, wandering around.'

Troy shrugged.

'I wanted to be left alone,' he said eventually. 'I couldn't bear everyone fussing over me all the time. People looking at me to see how I am.'

'You mean me,' said my mother. 'I'm the one who fusses. I know I fuss. I try to stop myself and stand back, but I can't help it. I feel if I could just help push you back on to the tracks, everything would be all right for you.'

'You should trust me.'

'How can we trust you,' asked my father, 'when you skip lessons and lie to us?'

'It's my life,' said Troy mutinously. 'I'm seventeen. If I want to skip lessons, that's my choice. If I fuck up, it's my fuck-up, not yours. You treat me like a little child.'

'Oh,' said my mother. It sounded like a moan.

'If you want to be treated like an adult, you've got to behave like one,' said my father. He rubbed his forehead, then added, 'It's because we love you, Troy.'

My father never says things like that.

'I'll make us those sandwiches,' I said, backing into the windy, half-wrecked kitchen.

When I came back in, carrying a tray loaded with toasted sandwiches oozing melted cheese, and four mugs of tea, my mother had red eyes and had clearly been crying. She said, ' Troy says he'd like to stay with you for a while.'

'Oh,' I said. 'Well, I'd love that, Troy. It'd be great. The snag is, I'm not living there at the moment, Brendan and Kerry are.'

'Not for long, though,' said Troy. 'I can stay there with them for a couple of weeks or so, and then you'll be back. Right?'

'You know how much I want you to stay,' I said, 'but can't you wait just for a week or so?'

'Why?'

I stared at him helplessly. 'Are you sure you'll be all right with Kerry and Brendan?'

He shrugged. 'They'll fuss too much as well. It'll be better with you.'

'So wait.'

'I need to move now.'

'I'll be around,' I said. 'Just call me when you need me, OK?'

'OK.'

The following day I took time off work and went with Troy to the Aquarium. We spent two hours there, noses pressed against the glass. Troy loved the tropical fish, glinting like shards of coloured glass, but my favourite were the great flat fish with their stitched upside-down faces. They looked friendly and puzzled as they floated through the water with their bodies waving. Afterwards I drove him to my parents' house to pack his stuff. Brendan and Kerry were going to collect him in a few hours' time. I hugged him hard.

'I'll come and see you there very soon,' I said. 'A day or two.'

In fact, hardly an hour passed without me discovering something that I'd forgotten. I actually had to carry a piece of paper and a pen around with me so that I could keep a list. I could buy more knickers, but I couldn't buy everything. Three more T-shirts. Nail clippers. Conditioner. Woolly hat. Chequebook. Street map. It was just ridiculous, so after work the next day I went to my flat with the shopping list. Inside, I found Brendan and Troy playing cards in the main room. They looked over at me in some surprise. Brendan said something, but I couldn't hear him over the music. I marched across the room and turned it down.

'I can hardly hear it,' said Troy. 'You'd have to put a stethoscope against the speaker to hear that.'

'I just popped in to collect some stuff,' I said.

'That's fine,' said Brendan. 'Go ahead.'

The very idea of Brendan airily telling me to go ahead in my own flat made me want to boil a kettle of water and pour it over his head. I couldn't speak. But then I did speak.

'How are you doing, Troy?'

'Pretty well, aren't we?' said Brendan. Troy smiled at me and raised his eyebrows.

I went into my bedroom. Unsurprisingly, this was where Troy was sleeping, and in only a day my room had started to look the way that his bedroom always looked. The bed was unmade, there were clothes on the floor, books lying open, a funny sweaty smell. I was as quick as I could possibly be. I threw some things into a carrier bag I'd brought with me. I pushed the door gently to and climbed up and reached for the book where I had hidden the money. I counted it and felt my skin crawl as I did so. Sixty pounds. I counted it again. Sixty. Couldn't he just have taken it all? What was he doing with me? I put the rest of the money in my purse. I went back out into the main room.