I swam towards the waterfall and clambered onto the rock shelf, not really caring any more what I looked like and that he was going to get an eyeful of my arse. There was just enough space to squeeze behind it. I sidestepped along the rock and half crouched, laughing uncontrollably as the water pelted down in front of me on fast forward. It sounded powerful enough to behead me. I shuffled back onto the shelf, my toes gripping hard.

Jim was swimming on his back. His beard looked all springy. ‘Thought you’d been eaten.’

There was a thin, delicate offshoot of water behind me, a silver chain. I stood under it, facing him, my hair plastered to my head, wondering how many porn scenes were set in a West Highlands waterfall. Probably loads. I lobbed myself back into the pool.

After a few more minutes of trying to catch those little insects on skates, dunking my head under and basically reverting to being nine years old, my feet were pinching.

I swam to the edge. ‘I have to get out.’

Jim followed. ‘Aye. Me too.’

On the rocks I began shivering like an idiot, hopping up and down and stamping each heel on top of the other foot. My toenails had gone blue. Jim gave me a towel to dry off with and disappeared behind a rock that stuck out like a half-open wing. I dressed incredibly quickly, a theatre actor between scenes, and he came back with his jeans and shirt on, sleeves rolled up, damp T-shirt crushed in his hand. When he saw me jiggling about he produced a hip flask from his bag and the burn of the brandy was the most perfect thing in the world.

We sat there for ages, the falls a mix of white and yellow solvent paint – Butt-Numbing Scottish Waterfall – and the sound blurry. I felt like my brain had been scrubbed. Goosepimples peppered my legs and my hair had gone as soft as anything. A glow spreading like warm butter on my skin.

‘You did all right, there.’ He was leaning back on his hands, his legs stretched out, bare feet crossed at the ankles.

I could see the corner of his boxer shorts that he’d crumpled up and stuffed in his pocket. I almost blushed, then. I should have done the same – my pants were soaking through my shorts, my skin going clammy.

I peeled a little weed off my arm. ‘You’re a bloody otter or something.’

‘Just used to it.’ He passed me the flask again and brought his knees up, resting his elbows on them. ‘The cold and wet’s part of us up here, is all.’

‘Is that why you’re all so fucking miserable?’

‘Aye, probably.’ He breathed a tiny laugh through his nose. ‘Cheeky get.’ The water had scoured him clean, too. His limbs seemed to have loosened.

The long white scar I had seen on his wrist stretched all the way along his forearm, widening in the middle and going right up to the point of his elbow. ‘How did you get that?’