And then one day you realise that the tiny voice in the back of your head is also the voice in another head, sitting on the back of yours, the skulls joined like a butterbean. The idea starts to fascinate you. You can't help waving your head around in public, rolling your neck, trying to feel its weight. It makes a symmetry, an economy. One voice, two heads. No wonder the little voice is screaming all the time, with two whole brains to talk to there can hardly be enough hours in the day.

You begin to wonder what life must be like for your other head. Not that it is really 'your' other head. You can't feel it, can't see it (although you've tried to catch it by surprise with combinations of mirrors), and none of your friends seem to notice it. You only discovered it by the process of calm, rational thought. Maybe they've all got other heads, you think, heads staring backwards forever at our disappearing footsteps, constantly being stifled in the cushions of sofas. Maybe it's not just a head, but a whole other inert body, just hanging there, being dragged involuntarily around. If someone falls face down from a great height, can the other body just walk away?

The little voice is getting more insistent. You start noticing a drag when you walk down the street, like you legs are heavy or as if someone is digging in against you. You keep getting flashes of the street behind you every time you blink. Soon it becomes tiring to walk up the stairs to your room. One day you get stuck between the second and third floor. You try pulling yourself up with the handrail, but you won't budge. You can just hear a faint sound of groaning from behind as you try to force yourself onward, but you feel weak. You can hardly grip the rail. You stop to catch your breath, and your head is jerked back as you move down two, three then four steps. You try to catch hold of the rail again, but your strength is failing and soon you're being dragged along the streets, trying to dig in your heels but you can no longer feel your feet. You scream at passers-by, at the policeman and commuters, but no-one seems to notice. You enter a building you don't recognise, get pulled into a lift packed with people. Their faces are impossibly close, their breath misting on the surface of your eyes. The lift opens and you are dragged purposefully away, only realising that your on the sixth floor when you see the red lights receding down the corridor. You hear the sound of a door unlocking behind you, and then you're in a flat, a plush place with a balcony and a soft sofa, the walls covered with mirrors. You try to catch a glimpse of the face that is pulling you around but you only see the back of a head that could well be your own.

After many years you realise that you'll never see his face, never eat or drink or walk forwards again. You dream of pushing him over that balcony, waiting for him to fall face down on the tarmac, so that maybe, just maybe, you can walk away, but he's clever enough to never go out there, and so your dream is just a dream.