I shrug. ‘Ideally, I’d live in the cloud tops of Venus with a girl from the future.’

Gus laughs and pats me on the shoulder. ‘You do that, mate.’

I set off to school. I wish I could get Troy’s football trophy out of my bag. I stole it twenty years ago, and yesterday. Whatever I do it stays where it is.

I get through the day being relentlessly lovely to everyone. I don’t bother to eat bricks or plates any more because that was novelty stuff and I’m bored of it. I chat to Lucas, and find that, as Ariel said, he just wants to be my friend. I can see that I haven’t been quite as cool as I thought I had.

‘Ça va, Joseph?’ he says in what I’d always taken to be a mocking tone. I think of the adult Lucas sitting by the canal with Ariel and Izzy, and know it’s more complex than that.

Instead of telling him to fuck off, or mimicking his French accent, I say, ‘Oui, ça va. Sorry you’re not coming on the trip, mate.’

‘Me too!’ he says. ‘You’ll have a great time.’

‘We should hang out when I’m back,’ I say.

It’s easy to be magnanimous under the circumstances, and I want to test whether it’s true that he wanted to be friends.

His face lights up. ‘I’d love that,’ he says. ‘Yeah. That’d be great. Cheers.’

I hang behind after registration to chat to Mrs Dupont, since she’s my stepmum. I do like her. Quite apart from her joining my family, I know that twenty years from now she’ll still be in this classroom, but she’ll be talking to Ariel, making sure she and Sasha are all right. She’s a link between us, a person who was already in both our worlds, and she will specifically look out for the girl I love. That makes me want to say something profound, but all I can manage is: ‘Thanks for being a great teacher.’ I look quickly around to make sure no one else is in the room. Luckily, we’re alone.

She grins. ‘Well, thank you for being a great student, Joe,’ she says, and she gathers up her books and bag. ‘You’re going to go on to do wonderful things with that charm of yours.’

I sit with Troy in the canteen. He eats a plate of school-dinner curry that I can’t smell, though everyone keeps saying it stinks and holding their nose. I eat a sandwich, just to look normal, and drink some water. I wonder where it goes? I guess it’s no more real than I am, so there’s nothing to go anywhere.

‘How are you doing?’ I say.

‘OK. Not bad. I lost my trophy.’ He frowns at his plate.

‘Oh, Troy!’