‘You want me to talk to her through a door?’ One day I would have a telephone conversation with my sister that didn’t involve the weary sigh of someone explaining something to a halfwit.

‘No, doofus. What it means is that if you’re going to get her to talk you need to be doing something together, side by side.’

On my way home on Friday evening I stopped off at the DIY superstore. Back at my block, I lugged the bags up the four flights of stairs, and let myself in. Lily was exactly where I was expecting to find her: stretched out in front of the television. ‘What’s that?’ she asked.

‘Paint. This flat’s a bit tired. You keep telling me I need to brighten it up. I thought we could get rid of this boring old magnolia.’

She couldn’t help herself. I pretended to be busy making myself a drink, watching out of the corner of my eye as she stretched, then walked over and examined the paint cans. ‘That’s hardly any less boring. It’s basically pale grey.’

‘I was told grey was the in thing. I’ll take it back if you think it won’t work.’

She peered at it. ‘No. It’s okay.’

‘I thought the spare room could have cream on two, then one grey wall. Do you think they go?’ I busied myself with unwrapping the paintbrushes and rollers as I spoke. I changed into an old shirt and some shorts and asked if she could put on some music.

‘What sort?’

‘You choose.’ I hauled a chair off to one side and laid some dust sheets along the wall. ‘Your dad said I was a musical Philistine.’

She didn’t say anything, but I had her attention. I cracked open a paint tin and began to mix it. ‘He made me go to my first ever concert. Classical, not pop. I only agreed because it meant he would leave the house. He didn’t like going out much in the early days. He put on a shirt and a good jacket and it was the first time I had seen him look like …’ I remembered the jolt as I had seen, emerging from the stiff blue collar, the man he had been before his accident. I swallowed. ‘Anyway. I went preparing to be bored, and cried my way through the second half like a complete loon. It was the most amazing thing I’d ever heard in my life.’

A short silence.

‘What was it? What did you listen to?’

‘I can’t remember. Sibelius? Does that sound right?’

She shrugged. I started painting, as she came up beside me. She picked up a brush. She said nothing at first, but she seemed to lose herself in the repetitive nature of the task. She was careful, too, adjusting the sheet so that she didn’t spill paint on the floor, wiping her brush on the edge of the pot. We didn’t speak, except for muttered requests: Can you pass me the smaller brush? Do you think that will still show through on the second coat? It took us just half an hour to do the first wall between us.

‘So what do you think?’ I said, admiring it. ‘Think we can do another?’

She moved a dust sheet and started on the next wall. She had put on some indie band I had never heard of, light-hearted and agreeable. I started to paint again, ignoring the ache in my shoulder, the urge to yawn.

‘You should get some pictures.’

‘You’re right.’

‘I’ve got this big print at home of a Kandinsky. It doesn’t really go in my room. You could have it if you want it.’

‘That would be great.’

She was working faster now, speeding across the wall, carefully cutting in around the large window.

‘So I was thinking,’ I said, ‘we should speak to Will’s mum. Your grandmother. Are you okay if I write to her?’

She said nothing. She crouched down, apparently absorbed in carefully coating the wall to the skirting-board. Finally, she stood up. ‘Is she like him?’

‘Like who?’

‘Mrs Traynor? Is she like Mr Traynor?’

I stepped down from the box I was using to stand on, and wiped my brush on the edge of the tin. ‘She’s … different.’

‘That’s your way of saying she’s a cow.’

‘She’s not a cow. She’s just – It takes longer to get to know her is all.’

‘That’s your way of telling me she’s a cow and she’s not going to like me.’

‘I’m not saying that at all, Lily. But she is someone who doesn’t show her emotions easily.’

Lily sighed and put down her paintbrush. ‘I’m basically the only person in the world who could discover two grandparents I didn’t know I had, then find out that neither of them even likes me.’

We stared at each other. And suddenly, unexpectedly, we started to laugh.

I put the lid on the paint. ‘Come on,’ I said. ‘Let’s go out.’

‘Where?’

‘You’re the one who says I need to have some fun. You tell me.’

I pulled out a series of tops from one of my storage boxes until Lily finally determined which one was acceptable, and I let her take me to a tiny cavernous club in a back-street near the West End where the bouncers knew her by name and nobody seemed to consider for a minute that she might be under eighteen. ‘It’s nineties music. Olden-days stuff!’ she said cheerfully, and I tried not to think too hard about the fact that I was, in her eyes, basically geriatric.

We danced until I stopped feeling self-conscious, sweat came through our clothes, our hair stuck out in fronds and my hip hurt so much that I wondered whether I would be able to stand up behind the bar the following week. We danced as if we had nothing to do but dance. Lord, it felt good. I had forgotten the joy of just existing; of losing yourself in music, in a crowd of people, the sensations that came with becoming one communal, organic mass, alive only to a pulsing beat. For a few dark, thumping hours, I let go of everything, my problems floating away like helium balloons: my awful job, my picky boss, my failure to move on. I became a thing, alive, joyful. I looked over the crowd at Lily, her eyes closed as her hair flew about her face, that peculiar mixture of concentration and freedom in her features that comes when someone loses themselves in rhythm. Then she opened her eyes and I wanted to be angry that her raised arm held a bottle that clearly wasn’t cola, but I found myself smiling back at her – a broad, euphoric grin – and thinking how strange it was that a messed-up child who barely knew herself had so much to teach me about the business of living.