'Sometimes we step into each others stories – perhaps just for a few minutes . . .' – Ghosts of Wind and Shadow, by Charles de Lint.

It's sad, sometimes.

A woman stands by the counter, talking to my Dad as he appraises the ring she wants to sell. There's a desperate harshness to her face. Her voice is quick and clipped, very steady. But I can tell she wants to cry.

My Dad doesn't ask questions. Sometimes people want to talk; they want to explain why they're selling their heirlooms, their memories, their kid's toys. Dad nods his head and listens, then gives them a good price. My Dad never cheats.

He hands the woman her money. She stares at it for a moment and all the harshness falls from her face. Her eyes shine, too bright. Then she stuffs the bills into her purse and leaves, letting in a gust of freezing air.

Dad sighs. He opens the jewellery display case and I go back to my homework.

I can't concentrate. I tap my pencil against the page of math problems and gaze out of the window at the falling snow. Beyond the swirling white I can just make out the darkening street. Our store is filled with muted shadows and the quiet rattle of the heaters. The air smells faintly of burning dust.

I shift in my rickety folding chair at the far end of the counter and take a glimpse over my shoulder. Dad's still got the ring in his palm, squinting at something on the inside of the gold band.

'What's it say?'

He jerks a little, surprised. 'Oh.' He puts the ring down into the case and runs a hand through his thinning, grey-streaked hair. 'Forever,' he answers. As he locks the case back up he says, 'Are you sure you don't want to go out?'

'I'm sure, Dad. It's too cold.' I want to tell him I like it here in our little shop, with its second-hand treasure trove crowding the floor, fighting for space. I want to tell him that I like being here with him. Tell him that I worry, that the apartment feels too empty when I'm there alone, even if he's just downstairs in the shop.

The bell over the door jingles as someone comes in. The figure is bundled up well against the winter; boots, trench coat, mittens, fedora jammed down over his face, and a scarf wrapped round so there's only the dark gleam of his eyes showing.

I'd be worried, but I recognise him. Not from his features, but from the clothes – he wears the same outfit each time – and his slightly hunched over posture. He's a short guy, but stocky; it's hard to tell if that's muscle, fat, or just layers of sweaters.

Dad recognises him too. 'Hello. Got something to show me?'

'Sure have.' He has a young voice, light and friendly. I can hear a smile in it.

He comes up to the counter and draws a bracelet out of his coat pocket. 'I don't know if this is worth anything . . .'

Dad takes it from him. I notice that the guy's mittens are fraying. There's a new patch, inexpertly sewn, on the coat. I wonder, not for the first time, if he's homeless. Maybe that's why he's always so bundled up. Maybe he's wearing everything he owns.

'Well now,' Dad says. 'This could be worth something.'

'Really?'

Dad nods. 'High carat gold, real sapphire – pity one's missing . . .' After a few minutes he hands the guy a sheaf of bills. He just stands there, staring, like the woman did earlier. Dad has bought some pretty eclectic stuff from him over the last couple of months, but none of it has been worth so much money.

The guy realises we're looking at him. I quickly get back to my math homework, pretending I wasn't looking at all.

'Do you sell coats?' he asks. 'Like this one?' He gestures towards his trench coat. Dad nods and shows him the rail of clothes tucked into the far corner.

Quiet slips over the store. I start working on a math problem, get bored, and turn the scribbles into a sketch of a woman. The woman starts to look like Mom, so I stop. All of a sudden the life seems to go out of everything. The store isn't cosy – it's cramped. It's not filled with treasure – it's filled with junk, things people didn't want, didn't need, or things people wanted to keep but couldn't, because they needed the money more.

The bell breaks the silence. We all look up – my Dad from a pile of receipts and paperwork, the guy from his perusal of the clothes rack.

A man stands by the door. He's tall and rangy, with a long, thin face. He takes two strides into the store and reaches into his coat pocket.

'Don't move,' he says, and brings out a gun.

No one moves.

'You,' the man says, waving the gun at my Dad. 'Give me the money from the till.' Then he glances over at the short guy in the corner. 'And you, keep still.'

My Dad doesn't move. I know what he's thinking; this is our money, our shop, we've just got it back on track and how dare he try and take it?

The man's confident veneer is starting to peel away. He licks his lips, presses them together.

'I won't ask you again.'

My heart is pounding so hard I think I'm going to be sick. 'Dad,' I whisper. 'Do you want me to do it?' I reach out towards the till. The man snaps at me not to move and my Dad breaks out of his trance, opening the till and scooping out handfuls of money.

'Put it in a bag.'

Dad stuffs the money into a brown paper bag. The man darts forward, snatches it up and steps back a pace. He glances down at the jewellery case. He's contemplating taking something from that too, but changes his mind.

'Your ring,' he says to my Dad. Up close he doesn't look confident at all; his eyes are wide and panicked and he breathes too fast.

Dad folds his hands together. 'My ring?'

'Give me it.'

'Please; you can have anything else, but my wife gave – '

'Give me it!'

Spittle flies from his lips. He's loosing control. Dad has the ring half way off his finger when a floorboard creaks, the man jumps in surprise and the gun cracks the air.

Dad jerks back, stumbles over a stool, falls to the ground.

The man stares at me and I know what'll happen next; he'll panic, he'll shoot me, and the guy in the corner –

The guy in the corner moves so fast.

He twists the man's arm and the gun drops to the ground. The man's cry of pain is cut off as a mitten-covered hand snaps up and hits him in the jaw, an audible smack of flesh on flesh. The man's eyes roll back and he's dropped unceremoniously to the ground.

I turn away, suddenly able to move again. 'Dad?' I drop to my knees. His eyes are closed and blood is spreading down his shirt, pooling under him. 'Dad!' I press my hands to where I think the wound is, high up on his chest, but all I can see is blood.

'Let me see.' The guy moves me aside. He kneels down next to me. I press a hand to my face, not thinking, and the blood gets in my mouth.

I realise I'm chanting under my breath. 'No. No. No . . .'

The guy gets up. I want to ask him where he's going but I can't break out of my chant. I hear him clattering around the store and then he's back, pulling off his mittens. He has two sweaters in his hands and a belt. He folds up the sweaters and places one either side of the wound and then ties them on with the belt, cinching it tight. He works quickly, surely, like he's washed blood from his hands before.

'It's okay,' he says to me. 'He's not dead, he's just been knocked out.'

I nod. I've still got my hand over my mouth. He gently prises it away. That's when I notice his hands are green and that he only has two fingers. Two fingers and a thumb.

My thought won't stick together properly, they keep falling a part, but I manage to think – oh, that's why he's so covered up, he's deformed. I don't care though, not at all, not when my Dad's bleeding on the ground and this man's just saved both our lives.

'Hey,' he says. 'It's okay. You're safe.' He takes my hands. His skin feels tough, like leather. 'Let's wash this off.'

'There's a sink . . .' I stop, clear my throat and try again. 'A sink in the back room.' The blood is drying thick and sticky. My hands itch. He pulls me up and I stumble through the dark back room, finding the sink mostly by memory. I let the water run until it's boiling and then scrub until my skin is red and raw. The guy leaves at some point and calls for the police and an ambulance. When he comes back he watches me for a moment and then turns off the tap. Puffs of steam float in the air. Without a word he leads me back into the store and makes me sit down in the chair where only a few minutes ago I was doing my homework.

He checks my Dad and then walks out from behind the counter.

'Where are you going?' I scramble up. 'Don't leave!'

He's got two more belts and is busy tying up the unconscious man. I try to guess what he's thinking, but I can't see his face.

'Don't leave,' I say again. I'm ashamed to hear the break in my voice and feel tears sting my eyes.

There's a long pause. 'Okay,' he says, 'but I'll have to leave before the police get here.'

I'm about to ask why, until I think about his hands. A dozen scenarios flick through my head. I discard them all, thinking only that I'm glad I'm not alone.

I sit down next to my Dad. His ring is still half off his finger, so I slip it back on. The guy sits down next to me. I rub at my eyes and swallow hard, past the lump in my throat. I start shaking, for no reason I can see.

I'm pretty sure he's speaking, mumbling in his quiet voice about how everything's going to be fine. I can't seem to focus very well, but it's still nice to have someone say the words. After a while he stops talking and I stop shaking and we fall silent.

I can hear New York, but can't see it. I can hear my Dad breath and see his chest rise and fall. I'm not alone as I wait for the police and I'm not an orphan. Slowly, slowly, tension ebbs out of me. Of course, I choose that moment to burst into tears.

He sort of flinches, like I've surprised him. Then he lets out this sad sigh and wraps one arm around me. I snuffle and bawl into my hands like an idiot. Weird thing is, I actually feel a bit better now.

He hears the sirens before I do.

'I'm sorry,' he says. 'But I have to go.'

'What?' I wipe my eyes and nose on my sleeve. I listen, and hear sirens wailing in the distance. 'Oh.'

We stand up. 'There's a back door,' I say and lead him towards it. I grapple with the rusting lock until he politely moves me aside and wrenches it back with apparently no effort. The door opens out into a dark, narrow alley. Snow blows in around us.

'Thank you,' I say, before he leaves. I want those two words to carry much more than they do. I'm trying to tell him I'll keep quiet about his hands, and that he can come back here if he wants; I'm thanking him for stopping the robber, helping my Dad, staying with me. But I don't have enough time and I've never been good with words.

I don't know how much of my unspoken message he gets. There's a smile in his voice when he says, 'You're welcome,' though, and I hope enough of it got through. He steps out into the alley and I close the door.

I stand at the counter and see the outlines of cars through the snow. At some point the store's become a treasure trove again. I kneel beside my Dad as the door opens and the bell rings out, and I know we'll both be okay.