I was conceived exactly three-point-five minutes after my identical sister Melinda. It is for this reason that I, Abigail Rose Meyer, am considered a second-class citizen.

The conception was not coincidental, nor was it immaculate. It was pure science. A standard procedure to protect the fundamentals. To create a surplus population.

I am a clone of her DNA, the Surplus Genetic Synthesiser scanning Melinda’s genome –my sister still a fertilised egg at this point- so that it could form mine.

I had been reminded of these expectations my whole life; literally from the moment I’d become an embryo. Implanted into my mother’s womb, I took the secondary position after Melinda. If something in our mother’s uterus became corrupt, it was predicted –and hoped- that my self would terminate first. It was practical; nobody wanted a fundamental to die if the surplus could be sacrificed.

We were schooled that in life, there are leaders and there are followers. Naturally, being a surplus, I followed. There was no argument about this; I had to remain within half a mile radius of Melinda at all times. Mostly, I walked two steps back, close enough to eavesdrop on conversations I wouldn’t otherwise be privy to.

“Did you hear about Matthew Connors?” Melinda says to Betty, a girl that barely meets our shoulder height. Betty’s surplus is Beth –most parents name their twins closely to avoid effort- a girl who hovers behind with me. She is meek and mouse-like, her thick-framed glasses swamping her face. Of course, Betty wears no such things. Their parents paid for the fundamental’s laser surgery years ago.

“No...he didn’t, did he?” Betty says, her mouth forming a shiny pink ‘o’. They do this, these fundamentals. Talk in code. They’d like to think it’s because myself nor Beth will be able to decipher it, and so they can have some privacy in our presence. I like to think it’s because neither really has a clue what the other is saying. Pretenders.

“He did.” Melinda nods, her long amber ponytail rippling like silk. I roll my eyes. Unfortunately, Beth sees me, her own mouth forming an identical, less-shiny ‘o’ to her twin’s. Surpluses don’t need lip-gloss; invisibility is encouraged. She disapproves of my judgement and eavesdropping. Although she is probably more annoyed that I am brave enough to show exasperation – we both know that she’s listening intently, too.

Up ahead, there are the gargoyle gates of Trafalgar High School. You would be forgiven to assume that every fundamental student is accompanied by their surplus. But you’d be wrong. Most of them are; sets of twins dressed in the tartan uniform. Their only individuality the school bags and hairstyles (which, mostly, they share).

But a few surpluses are absent. Some are legitimate; Corrissa Jone’s sister Larrissa came down with the sneezes last week, and hasn’t been seen since. She’s been tucked up in the infirmary, surrounded by bouquets and get-well-soon cards. Nobody wants a surplus to be ill; think of the possible consequences to the fundamental. Most of us (surpluses) know that Larrissa is milking it by now – she’d been healthy for at least four days. But still, who could blame her? Hospital stays are the most luxury we’d get, I’d say.

Some surplus absences are more sinister. Suicides aren’t uncommon, and others go to a better place. They are the rebellious ones; the ones who don’t follow the rules. Officially, that ‘place’ is prison, or if they’re lucky, reform school. But we’re not stupid.

Then there are the other types of solo twins; the weird ones. So rare, in fact, that most fundamentals don’t even believe in their existence. Because, how is it possible that a fundamental dies, whilst their surplus survives? Well, it’s perfectly possible, because I’m looking at one right now.

Leaning against the brick wall, my only friend Tristan Gosling is stood. I wave and he jogs over to us, hovering respectfully behind the fundamental girls in front. Melinda shoots him a disdainful glance, sour grapes at not being ‘the chosen one’.

Tristan has this effect on most females, surplus or not. He is tall and sandy-haired, his tan skin taught over a chiselled face and body. His blue eyes stare brightly, savagely, challenging anyone and anything. He is rugged, no doubt, and so masculine and different to the other males here it’s almost intoxicating.

His fundamental, Trevor, died last year from an inoperable brain tumour. Usually for medical treatments, surpluses are sacrificed to save their twin. We are literally living organ donors. But how can you replace the one thing that makes your soul? A brain transplant was out of the equation, so Trevor withered away through the short yet painful months.

There’s nothing in the rules to say that he has to talk to Melinda, though, so he ignores the glowering. Playfully, he punches me in the arm and I ignore him, pretending to be far more interested in my fundamental’s conversation. He falls in line, knowing I won’t budge on this. At least Beth can keep him company.

We shuffle through smaller gates, barbed wire loops overhead against a gloomy sky. An omen, no doubt. The thirty-one-hundred strong student body swarms as we get into lines, filtering through the banal ordeal of metal detectors. Once inside, I am safe to roam freely.

I nod to Melissa, who stares blankly at me as I walk away. Tristan follows, a bubble around us as people move out of his way. I amble into the registration room, then walk without word to first period Chemistry. Tristan has Math; we’ll see each other later.

I assume my surplus position on Melinda’s right hand side of the desk. On her other side is Cory Davidson, her boyfriend. His twin, Carey, really is identical – I wonder how she manages to tell them apart. That is, until Cory opens his plump mouth and the arrogant drivel that falls out is unmistakably fundamental. I nod to Carey, who pulls out his own notepad and paper.

Of course, no government wants to admit that we’re second-class citizens. They’d like us to believe the veneer. Vain phrases such as classless society, equal opportunities are banded about as policies, billions spent advertising these lies. In reality, it comes down to this; I take Melinda’s notes, she blows bubbles of gum. Such is our classroom life.

Our parents treat us fairly – as fairly as a surplus can be treated, I suppose. I am encouraged, my academics and efforts praised, rewarded. Positive reinforcement for remaining dedicated to my studies. Our mother, Helen, even thinks I’m smarter than Melinda. (I am, but still.) We all know why it’s encouraged, though. Like so many surpluses, I will be expected to financially support my fundamental, seeing as she can’t even write her own homework without copying mine. I will be expected to make a living for two people, just to survive. Oh, joy.

But I have a plan, I think, scrawling down the title of today’s lesson. Equilibrium. I already know the principle; something cannot occur without consequence. Shifting something is accommodated for by its opposite. Fifty-fifty will change to seventy-thirty; nothing can be more than one hundred percent. And this existence is wrong; something has to push back. Nature will dictate; it is how we survive. Living like this -a servant, a slave- will only last so long before the equilibrium pushes back. For every action, a reaction. Something just has to set the ball rolling, and I intend to start that momentum.