‘Do you remember when she cut all Dad’s roses at the same time and displayed them around the house in every vase and bottle and mug she could get her hands on? And when Dad came home he couldn’t believe she’d cut them all off at the nub, so that basically put paid to them flowering again for another whole year.’

‘I do, yeah.’ I slowly peeled back the silicone dressing on Lou’s leg, thinking I remembered that occasion almost too well, because I’d been the only one who’d seen the look on my father’s face when he realised Mum had just lopped off what equated to twelve months of hard work in one go. Even so, he still smiled at her like she’d presented him with the Hope Diamond when she handed him a single yellow bud. It was funny Lou remembered it, though, because she couldn’t have been more than five. Maybe I hadn’t been the only one who saw that look after all.

Once Lou’s leg was exposed, we both leaned forward to have a closer look at the wound. It looked neat, dry and clean, its crusty edges creeping their way towards the middle of the volcano a little more each day. It was fascinating to see the resilience of Lou’s skin in action, but I knew from what Dom had told me that it was what you couldn’t see that could turn into a problem. I studied the edges carefully, looking for any warning signs or changes in texture and colour.

‘I was always jealous of you, Danny.’

Lou’s voice was very soft, but there was no mistaking what she’d said. Under my hands her leg felt frail and papery, and I had a sudden, terrible urge to squeeze it, as if that might stop her saying any more. But I knew it wouldn’t, because this boat had already started to rock. All I could do was don a lifejacket and hold on.

‘I know it’s silly, but I used to think about how you had all those extra years with them before I came along. Like the three of you had a secret I’d never be able to be part of.’

In the silence I was scared I might involuntarily blurt out a reply, because it was there, on the tip of my tongue. And because she was right. I tore off a too-big wad of cotton wool and dunked it in the bowl, trying to remember the time before my family had included Lou. But it was hard to get a handle on the slippery memories, and I had a sudden urge to dive headfirst into the warm water.

‘She thought you were an angel, you know.’ I wondered if I could make a forward somersault, half-twist work.

Lou looked down at her hands resting in her lap, like she didn’t recognise them, like someone else had left them there and run off. The sharp smell of antiseptic was making me feel a bit light-headed and I wondered which one of us would call the ambulance, because a grown man had just heard his mother thought he was an angel and it had made him see stars.