The first thing Ace notices is that she has managed to land on the hill. Shortly after, she shivers as memories of days yet to be race through her mind. No blood has been spilled on this soil yet, not for another six years. She twists the key to kill the engine and wheels the anachronistic motorbike down the slope. If it weren't for the reading on a tiny monitor next to the fuel gauge, she might have thought she'd landed in the wrong time. '1983' shines in bright green numerals. Roughly six o'clock in the evening, she estimates. The scent of overly cooked potatoes carries from the houses nearby as she conceals the bike behind thick foliage.

Definitely six o'clock, she decides as she wanders into the diner and watches waitresses frantically distribute dishes. Her stomach swirls at the sight of three familiar faces. Half a plate of chips sits uneaten in front of her, her eyes trained on them, their names on the tip of her tongue. Her right hand grips a fork tightly as the boys at the table across the room make a mess of the remains of their meal. They laugh as glasses overturn and their contents drips onto the floor and as they are chased out of the building by a frustrated manager.

In six hours those boys will commit murder.

In nine hours a teenage girl will begin screaming.

In eleven hours there will no longer be a house on the hill, only smoking ruins.

And it has to happen.

Ace's eyes close as she tries to calm her aching heart. It has to happen...

She watches her younger self argue with her mother. It could be any other night as the door slams and pillows get pounded viciously. Tomorrow will be different though. Life would suck a lot more than it did today. The girl who refused to show fear would scream. A policeman will arrive at the door a few hours later and seize everything stashed under the mattress; the canisters, the vials and the chemistry set that had been hidden from her mother for six weeks after she confiscated the last one. After tomorrow the teenager will be shadowed to and from school by a probation officer. By this time tomorrow she'll begin to regret burning the house on the hill down and start wishing she'd blown it up instead.

Ace's footsteps echo down the street. This, she thought, is the hard bit. She has lost track of how many times she has thought about this and wished she'd had the courage to ask to be brought here. It's something she knows she has to do alone, not with someone looking over her shoulder or reminding her that she couldn't change the past. That would only make it harder to watch it happen.

Just here to watch, she reminds herself. No interfering. No creating your own future again. No matter how much she wants to swoop in, grab the hand of her doomed friend and rescue her from her fate, she couldn't. Running is her speciality and they could run so far. The bike could take them anywhere, any-when, where nobody could ever hurt her again... But the dominos would fall differently if she did. She might never end up travelling through space and time, might never get to this moment and then time would revert back to the way it was supposed to be.

From the shadows, she watches the trio approach the house. Her face is already streaked with the tracks of tears. Not a drop seeps from her eyes when the match is lit. She has none left. The light in the bedroom went out hours ago but the bottle's contents catches alight and casts shadows onto the walls. It takes only minutes for the flames to find the gas pipes. Glass shatters. A roar echoes through the night. Her fingernails draw blood from her palms as the boys scamper at the sound of the sirens. Like a sentinel, she stands there until the sun rises. She hears herself scream, her younger self having arrived in her flannelette pyjamas. The nightmares of flames will begin tonight.

Her eyes catch on someone running in the distance; the Doctor. Her throat tightens as she tries to swallow. He's just arrived and doesn't know why the teenager is screaming until his steely eyes scan the crumbling building. He follows her when she breaks away from Audrey. He will watch her go to Gabriel Chase. He doesn't stay to see what she does there.

The crowd having dispersed, Ace walks over to the remains. "Manisha," she calls quietly, "I'm sorry..." She carefully retrieves a piece of paper and unfolds it. Her mouth opens but no words leave. Breathing is difficult enough. She reads it quietly to herself instead.

'You were always the best thing about this stupid place. Mum was always telling me to grow up and stop being such a kid and I finally did; the hard way. I didn't grow out of it, it was torn from me. You were taken from me. Every day I saw their faces and they dared to meet my eyes. They knew I knew. In my nightmares I watched you burn and they would smile.

I don't know which day will be my last or when I will join you, but I know you'd want me to fight until the end, cling to life. You always were the patient one, waiting for me. Me, well I was the explosive one. Saw myself as your protector, standing up to your fears and fighting your battles so you wouldn't have to. I punched that Chad boy on the first day of school because he called you names. You smiled as you told me I shouldn't have broken his nose. You called me Ace from the first time I asked you to. You laughed when my first Nitro experiment singed off my eyebrows and half my fringe.

Even when it all fades to black or when I can hold my breath no longer, I see you in the light shaking your head, your midnight hair shining and your eyes so bright. I hear you tell me 'Not yet'. You push me back because I still have battles to fight and people to protect. And I do, tooth and nail, weapons and words. I shout and strike at the dark and I keep the monsters at bay, the way I tried to protect you.

You told me you believed in an afterlife. Not sure if I do but if there is one, I know you've made it there. You're watching me from up there. There's been too many times where I've been close to death to think I escaped due to sheer luck. No, I know the reason.

It's because you are my guardian angel.'

The paper is folded and gently dropped into the remains of the fire. It shrinks as the flames nibble at the edges before crumpling into ashes, embers and dust rising into the sky.