And he's laughing. "I dunno. It's an analogy."

Now I'm laughing. "Oh, it's an analogy, is it, Joseph? And since when do you make analogies?"

"Well, when your boy goes off to college and starts mingling with college types, you need to step your game up, don't ya?"

He grips the steering wheel dramatically, pretending like he's trying to control a spiralling jet fighter, and waits for my reply. I just look at him, then blow a raspberry with my tongue. "There's your analogy, old man."

And we laugh together as we turn on to the high road.

Our laughter fades out as we drive down ours and he pulls up outside the house. You can see the hall light is on through the glass top of the front door, but we both know the house is empty.

"You wanna cup of tea or something?" I say. Dad looks at the house.

"Better not, wouldn't want to get too comfy, eh?"

I unbuckle my seatbelt. "OK. Enjoy your chips then."

"Luke," he says and I sense something coming. He turns to me, his chunky hands in his lap. "We can talk. I mean, if you want to."

It's not what I was expecting. I know how hard it is for him to bring it up. I've thought about it lots of times. All his size and strength didn't count for anything when they sent his son down, and I know he would've done the same thing as Marc if he'd found out first. I know he doesn't speak about it to anyone. I know not speaking about it drove the nails into the coffin of him and Mum.

"He couldn't handle you seeing him, you know?"

And, just like that, there's a tiny crack in the wall of him.

I can't help staring. "What?"

Dad won't look me in the eye, but he carries on. "He made me promise not to bring you, for visits. Your mum too. He didn't want either of you seeing him in there. Me either. That's why I stopped going."

It's the most he's said about Marc since he's been away and I don't know where to look. Our road is dark and quiet.

"I told him. I told him, Luke. One's enough. One good punch and walk away. One ..." He breathes through his nose like an animal. "Him who can't hear, must feel. Eh son?"

I say nothing. Just sit next to my old man, feeling more like a grown-up than I ever have.

Dad shifts in his seat. "Anyway, that chippy'll be shutting. I'll see you, Lukey." And the moment's over and I'm about to get out, when he grabs my head with his big hand and pulls it towards him, kisses me on the crown, then pushes me off. "Go on, get home."

I watch the car drive away, the red brake lights as it reaches the corner, then it's gone. One small scene. The least amount of words, but it feels like somebody just lifted up the heavy rock of my dad and showed me something growing underneath.

I'm walking up the hill to college. It's Tuesday.

I've convinced myself that 'brooding loner' is my persona of choice. I'll find a different seat in film, and if there isn't one, I'll just style it out and keep quiet till Leia gets the picture.

As I get to the campus, my phone beeps. It's a message from Tommy: Yo, hurry up and hook me up with one of them posh girls, Lukey, don't be tight. T I picture him sitting on a stack of paving slabs, smoking a cigarette in between middle-aged builders with thick necks and rubbish tattoos as I type a reply: Sorry mate, they're all only interested in me. Animals they are. I'm knackered to be honest. See you tomoz I read the words and stare past my phone at the floor as I click send.

Groups of people are walking towards different lessons in different buildings and even though he'd probably do or say something to properly embarrass me, I'm wishing Tommy was here right now.

Leia isn't there when I walk into class, but there aren't any other spare seats besides the one next to hers so I just sit where I did before, and prepare myself to play it cool. A pale girl with the sides of her head shaved and a ponytail is playing music through her phone to the blonde girl next to her. They both stare at me as I sit down and I make myself not look away. Get a good look if you want.

Noah's sitting at the front, just watching people as they talk, then Leia walks in with Simeon and I pretend not to notice.

"Hey," she says, as she sits down next to me. She's wearing a black Stussy hoodie and it's probably a birthday present he got her when they were going out or something. Definitely. I nod without speaking and stare forward like I'm ready for the lesson to start. I watch Simeon slap palms with the chunky rugby boy as he sits down and I try and give him a nosebleed with my mind.

Just forget them.

Noah slams his hands down on his desk and everyone jumps.

He stands up slowly and turns to the whiteboard. He's acting differently, like he's waiting for something, and pretty much everyone's eyes are trained on his back as he pulls out a marker and starts to write.

He does a big letter S, then a capital H. A couple of people look at each other, then back at him. As he starts the straight line of an I people are starting to chatter. Noah steps back from the board without turning around and holds his arms out like a conductor.

What's this guy doing?

And it shouldn't be a big deal really, a teacher about to write the word SHIT on a board, but it feels like we're all breaking the rules together. Then Noah steps forward and curves the I round and up into a U and writes SHUT UP. And everything's quiet. He turns round and he's smiling and I'm thinking, right now, that must feel amazing.

"You hear that?" he says. People are looking round, out of the window and shaking their heads. My eyes don't leave him.

"Somebody just fell in the shower." He tilts his head slightly as though he's listening for it himself. "You hear it?" He raises his index finger.

People don't know where to look, but I've played this game. I still play this game all the time on my own and I like him. I like you, Noah.

"No one?"

He's starting to look a bit let down. Nobody else even seems like they might be getting ready to speak. Then my hand goes up. What are you doing?

"I heard it."

Get your hand down now.

But I just keep it there, as everyone's eyes turn to me. Noah cracks a smile. "Thank you ..." He's leaning forward, waiting for me to say my name.

I lower my hand. "Luke. My name's Luke."

I can feel Leia looking at me on my right, but I stay with Noah. He nods. "Good. Now the real question is, Luke, are they dead?"

And it's like the scene is ours. Me and him with an audience either side of us. Simeon's staring back, but I don't care. This is why I'm here. What? This is why I'm here.

"No. He's not," I say, and my blood is electric.

"Ah," says Noah, "so he's a he?"

And the room is gripped and I can feel ideas flicking through my head like holiday photos in fast forward.

"Yeah, he's a man. A young man, and he's not dead, he's just lying down."

As the words come out of my mouth I picture Marc, curled up on his side in a white shower cubicle, like Michael Biehn at the start of Terminator, steam rising as water falls on him.

The girl with the shaved head frowns. "That's stupid."

People look at her. I stay on Noah, as he says, "Is it?"

"Yeah," says the girl. "Why would somebody just lie down in the shower?"

Noah looks at her. "And that's why it's brilliant." He points at her with one hand and at me with the other. "Because you want to know."

My throat's dry as I swallow, but I feel great. He said my idea was brilliant.

Then Leia speaks. "It's what he does." All eyes move to her.

I turn in my seat. She's leaning forward, like she's getting ready for a race. I stare at her mouth as she says, "He waits until his family have gone to work and then he runs a shower and he lies underneath it in the bath. It reminds him of the rain."

Then she's looking at me with those dark shining eyes and I'm looking back at her and it's so clear. There's something there. There's definitely something there.

"Amazing!" Noah's clearly excited. "You two have to work together."

No wait ... Brooding loner, remember?

But then Noah claps his hands and says, "OK, everyone! Pair-up and wait for your sound. Find your character. Start where it matters. In a moment where things hang in the balance. Show us that moment, offer us a question that we need to know the answer to. I'll come round and hear ideas. Ready? OK. Go."

For nearly an hour we talk ideas.

I suggest something, Leia listens, then she gives an idea and I respond, and back and forth again and again as we build up our character and his backstory together. Her ideas are brilliant, and the whole time we're talking it's like I forget everything else as I just watch this story we're creating grow out of nothing on the table in front of us.

By the time Noah works his way round to us we've got a sketched-out scene and both of us are charged.

"Come on then," he says, squatting down in front of our desk. His eyes are excited.

I look at Leia, she looks at me. "You wanna start?"

"No, you can."

And her face lights up. "OK, so it's morning, right, Luke?"

I nod. Noah watches her.

"So it's morning, late morning, like half eleven or something, and he's lying down in the shower. It's a bath actually, one of those cool free standing ones with the feet and there's steam as the shower's raining down on him. He's nineteen."

"What's his name?" Noah asks and we realise at the same time that we didn't give him one.

I hear Marc's name in my head. Then Leia says, "Toby. His name's Toby."

Noah nods. Leia carries on. "OK. The house is empty. His dad's at work and his younger sister's at college. She's nearly seventeen."

She uses her hands as she talks, like Mum does, and it hits me that maybe Toby is her brother's name in real life and if she's using real details then he's the same age as Marc.

"So he's a scientist. Physics, actually, and he's working on a really complicated theory. The shower helps him think." My stomach's dancing as she speaks and my pen rings a circle round her email address that she scribbled on my pad.

Noah frowns, but in a curious way rather than unhappy. "Where's Mum?" he asks.

Leia taps her pad with her pen. "She left, but when Toby was little, she used to have baths with him. They used to sit in the bath together and put the shower on and pretend it was raining. It's a good memory, like his happy place, and now it's his best place to think."

Did her mum leave?

Noah's eyes are narrow, like he's following her train of thought. "I see. So it's like his connection to Mum, even though she's gone?"

Leia nods. "Yeah. Exactly. It gives him clarity."

"I like it," says Noah, then he looks at me. "And what's this theory then?"

I glance at Leia and clear my throat. "Time travel."

Noah's eyes widen and I feel my face smiling. "Time travel?"

"Kind of. Not backwards in time, that's not possible, but he thinks he might have figured out a way to see into the future. Maybe."

Leia cuts in. "We're not sure yet. He's like this super brain, but kind of a recluse. He finished his first degree when he was fourteen."

"And he has these dreams," I add.

I made the dreams bit up on the spot and look at Leia nervously, but she nods with wide eyes to let me know she's cool with it and for some reason I feel the urge to hold her hand. I don't, obviously. Then it's the end of the lesson.

Noah stands up and scratches his chin like he's thinking and I don't want this to be over. Leia looks up at him. "What do you think?"

The pair of us watch him. He slides his hands into his pockets and I can see the muscles in his upper arms through his thin cream shirt.

"I think it's brilliant."

And I laugh, out of nowhere, like a fat HA!

What was that? I feel myself shrug, but it's all right because Leia's beaming. Then Noah says, "I think you've got something here. Something to run with. Well done. Keep working on it together, yeah? You're obviously a great team." And I feel myself straightening up in my chair.

"We will," says Leia.

I start to pack my bag and I'm glowing, like I just won a race.

Then Simeon is standing in front of our desk. "How lame was that?" he says, and my glow flicks off, like the bulb just popped.

Simeon's rolling his eyes and pointing with his head towards Noah at the front of the class.

"What's this guy's thing for picturing people in the shower? What a perv." He forces a laugh and I feel my shield coming up.

"Lame?" says Leia. "That was amazing! Wasn't it, Luke?"

And even though it was, even though it was easily the best lesson I've ever had in my life, and even though she's looking at me knowing that we just shared something that felt sort of magic, I just shrug.

"Dunno." And I get up and leave.

Good lad. Keep it cold.