Sine, cosine.

Upsurge and backwash. I am listening, listening very intently to the rush and ebb of the waves on the shore, to the sound wafting in through the open window, listening and waiting for you and trying not to think. Upsurge, back-

‘Hello,’ says the nurse. She glances at the open window, and then, not bothering to ask, smiling but business-like, goes to close it. ‘We’ll be starting in a minute.’ Another quick glance down at my fingers. ‘You’ll need to remove that.’

‘I should know by now. But no: half the time they have to remind me. I slide the ring off my finger: a pair of metal wires, gold and silver, coiling about one another like twinned snakes, strands of DNA. I cradle it in the palm of my hand as the nurse rolls up my sleeve, then sets about connecting me to the Path(o)x system. Here is another, far more complex set of wires. Yet I don’t feel a thing as each neural end slithers under my skin and connects with my nervous system.

‘You are wired up already when they wheel you in, and just need connecting. You are conscious, but your eyes are glazed and don’t seek mine. You seem unaware of your surroundings. Your skin is ashy, and taut over your bones, but the flesh beneath is slack with whatever they have pumped into you.

‘As the machine starts humming, I feel the nurse’s approving gaze on me. But I don’t want her approval. Don’t I? The rest of me might like someone to hold my hand, hold me, tell me how I brave I am.

‘First, a familiar tingling up my arms – muscles tensing beneath my skin, outside my control, small animals, snakes or mice. Then the pain. Familiar too. A member of the family, my inconvenient in-law.

‘Sine, cosine.

* * *

‘I remember when the disease first struck, when the pain invited itself in. I was horrified, of course. I wanted to do anything to protect you. Wanted to share it. And some part of me was proud of it: because it was how I knew I loved you, short as our relationship was then.

‘’It’s going to be like this,’ you told me. You were unsurprised – the disease ran in your family. Airy’s Neuropathy: a collection of symptoms (degenerative nerve damage, impaired movement and cognition, and above all the pain that claimed and wrecked you) with few explanations and fewer treatments. You’d always expected it. ‘There will be highs and lows.’

‘’For you and me both,’ I said. ‘We’ll help one another through it. Like…’ I thought for a second, came up with the stupid metaphor. ‘Sine and cosine. When you’re low, I’ll be high for you. When I’m low, you can be there for me.’

‘Later, when we took the tests, and passed – compatible, eligible for use of the newly created Path(o)x system – I was elated. Glad to be able to assuage some of your pain, of course. And proud, again. Self-sacrifice, sanctioned by science.

* * *

‘As I curl up and tense on the hospital bed, trying to find any position that will soothe me, however temporarily, you relax in yours. I fight the urge to be sick. You breathe in deeper. Some colour returns to your face. You almost resemble the person I fell in love with, years ago.

* * *

‘Path(o)x was sold remarkably well. Guaranteed pain relief in otherwise intractable cases, the possibility of neural regrowth and long-term improvement. It worked through brain- and nerve-stimulation, I learned, patterns of stimulation all the more efficient for being modelled on another’s nervous system. But what that fine-tuning meant – and here the saleswoman leaned back behind her desk, suddenly grave – was pain, for the sharer. Not always, but – often. Very often. Severe. She had to warn us.

‘I imagined the pain as liquid, cleanly and efficiently poured from one body to the other.

‘But nothing is clean. Nothing that humans share. I don’t mind – I kissed the sweat from your skin once. But I think back to myself, sitting in that office, with its smooth graphs plotted on gleaming white surfaces, dreaming a perfect, sterile future, and a perfectly balanced exchange.

‘I didn’t account for my weariness at appointment after appointment, no matter how nice the hospital. Hours lost in transportation, waiting rooms. The sight of you crumpled on a bed, the antiseptic smell I’ve come to hate. My own body rebelling (what a fool I’d been to ever crave pain). The thoughts that snaked in. Not exactly resentment, or regret, just thinking: what if I hadn’t met you? what if I’d never kissed you? Not cowardice exactly, just thinking: what if I left?

* * *

‘It hasn’t been one-sided. Saying otherwise would be a lie. I remember: you in remission, I jobless, inexplicable decompression, depression. We didn’t use Path(o)x then. I remember you holding me, stroking my hair, my back. Coaxing me out of bed, into life.

‘It’s never been a perfect transfer, a perfect exchange. The waves have never been so smooth. Our lovers’ mathematics didn’t account for that – our slow diminishing.

* * *

‘We’re not always below zero. After they unplug us, I lie in bed, shivering under the coverlet, waiting for the trembling to stop. I listen to the sound of the waves. I watch you. My ring is back on my hand, and yours, loose on thin fingers, is too. I wait until you open your eyes.

‘You look at me, and your eyes are clear. You smile. It’s a tight, weary smile, and you’re not oblivious, I know. You’ve seen my fears, and you’ve taken them in, you’ve made them yours and then given them back to me, augmented. How could you not? But for now you smile, weakly and through what’s left of your pain, because you love me and I love you.

‘And I think: we’ll have another go yet, another turn, another sinking and another rising.

‘Sine, cosine.