I saw a look cross Gus’s face and recognized the feeling that had hit me when I read the book about the mum. Sibling things must be complicated for him. I felt it stabbing me through the stomach. Gus’s brother had gone out as normal and never came back. I imagined Sasha doing that.

‘I can’t wait to meet your sister’s baby,’ said Zara, and I was so happy I wanted to hug her.

‘That would be great, wouldn’t it?’ I said. ‘I’d love that too. You can come to our house, if you like.’

‘I do like.’

Gus went upstairs to change out of his suit and came back down in a T-shirt and the sort of shorts people’s dads wear. As he walked over to us, Coco scrambled to lie on the sofa and pretended to be asleep, pulling a blanket over herself.

‘Wake up!’ Gus said. ‘Wake up, Coco.’ He did a theatrical walk towards her. This was obviously something they did.

‘Can’t,’ she said out of the corner of her mouth. ‘I’m a zombie.’

‘I am a zombie,’ said Gus in a monotone. ‘I will eat your brains.’

‘You used a robot voice to be a zombie!’ said Zara. ‘You’re silly!’

Coco leaped up and put her arms out like a zombie. ‘You are silly,’ she said in a robot voice. ‘I will eat your silly brain.’

Gus looked at me. ‘Sorry,’ he said. ‘It’s a game called robot zombies. It goes years back.’

I was standing on the doorstep, saying goodbye, before I got a chance to blurt something out to Gus.

‘Zara told me about your brother,’ I said, and I saw the jolt of surprise. I thought of Joe singing the Teletubbies theme song in my history class today, then pushed the memory away. ‘I’m really sorry. My mum died last year and I know how …’ I couldn’t say any more because a tide of sobs was trying to come up instead of words. I was supposed to be talking about Joe, not my own feelings. But it wasn’t something you could compartmentalize.

Gus reached out, but his hand hovered above my shoulder before he retracted it.