Michael combed and recombed his hair and watched Picasso. Picasso had flung himself down on the sandy carpet as if it were a bed. He lounged up a hand to accept a cup of tea that Marta had managed to assemble from the scattering of her kitchen.

Picasso was vain; he seemed to think the smell of his sweat was manly, virile. He did not bathe every day.

The smell of Picasso permeated the flat. It was not an unpleasant smell, certainly not to Michael. It was a sexual smell. It was as if the very air were stuffed with Picasso's penis. All three of them, wife, lover and anxious husband, could not think of anything other than those powerful genitals.

Mr Miazga was pale and thin-lipped, and sat on edge, hands clasping his knees, his delicate down-turned face looking as if someone had farted. Mrs Miazga's movements were anxious, faltering. She was disoriented. Her fine blonde hair came increasingly undone. It seemed to be falling out, drifting to the floor.

Michael took stock. Well, he told himself, you could have had a very clean pub manager instead. Instead you chose Pablo Picasso. It will be exciting, Michael. It will not be easy. And it may not last forever.

Michael could see the moment when Picasso wanted to get back to painting. In one single rolling motion he was up from the carpet and pounding the palm of his hand with his fist. He looked around the flat as if all of it, the original ownership, the sale, the move, had been his own work. He nodded as if to acknowledge the good job he had done. He said, direct to Michael, 'Come, we go to our home.'

Then Picasso took Michael's hand. It was evidently unpremeditated, thoughtless, sincere.

Michael found himself grateful and slightly weak at the knees. So, evidently did Mr Miazga. He settled back in his chair from relief, and his chest expanded, and his eyes zipped left towards his wife, and then widened, once. See? he seemed to say. I told you. They are lovers. You get all excited over a man who is homosexual.

After they left, outside on the landing Picasso promised, 'I will have the wife.' His voice was airy, amused, and he spoke out of the corners of his mouth as if Madame Miazga were a cigar.

The new flat in Camden was dark and in disorder. Street lights outlined the crags and valleys of jumble. Michael was given no time for regrets. Picasso herded him to their unmade bed, driven by a lust that Michael knew that he himself had not inspired. Picasso wanted Marta.

Picasso dozed and then woke up with a snort. He flung off the single summer sheet, and padded into the sitting room, leaving Michael in the bed. Lights blazed around the edges of the bedroom door, and there was a sound of assembling, plugging in, mild swearing. Michael finally admitted that he was awake and would not sleep. He stumped downstairs into the sitting room and saw Picasso at 2.00 am, sitting in front of the computer playing Myst. His bare buttocks hung over the edge of the chair as round as peaches.

'Hmm,' said Picasso. 'This is not three-dimensional… you just move closer to the drawing.' On his right, there was a pad and scrawled sketches of the Myst world populated with drunken people and smiling goats. Their smiles were drawn as a series of single unbroken spirals describing cheeks. Michael glanced down over Picasso's body. Picasso worked erect.

'Coming back to bed?' murmured Michael.

'I don't know,' grunted Picasso.

In the morning, the bed was cold and when Michael went downstairs Picasso still sat in front of the computer with a cup of cold coffee and strewn stale bread. Had he been up all night?

'You eat too much,' Picasso announced, in a bad mood. 'You will get fat. You will become a drunken boor.' He sighed, as if it were inevitable. 'Do not expect me to cook you breakfast,' he said. He slip-slopped his way out to the roof garden, carrying his coffee, escaping Michael. It was summer, warm, with beautiful light over the ferns. Michael joined him and Picasso said, 'You missed work yesterday and the day before. If you were more dedicated, you would do a better job.'

Picasso wanted him out of the flat. Michael showered, and deliberately took his time over coffee and yoghurt and bananas, and pointedly washed up – not a Picasso habit – and left at his usual time feeling bloated around the eyes and saddle-sore.

No one at work mentioned that Michael had missed two days. He began to explain that he had had to move flats suddenly. No one asked him any questions about it. Ebru and Emilio were quiet, brisk and business-like, as if Michael were a customer they would attend to in a moment. He filed slides and looked at data, and by the end of the day realized that he had spent it alone.

When he got back home, he found Picasso at the computer, now wearing Michael's best Japanese bathrobe. The game was noisier and the images moved. A tiny alien leapt and jumped and avoided being fried by robots.

Picasso kept playing. 'She is softened and ripe and if you are a man at all you will have her,' he said. Then he looked up. His eyes were angry and hungry. 'Do it because I tell you. I will like fucking you better if I think you are a real man.'

Upstairs, Mrs Miazga was in Michael's bed. She was huge, pink and dishevelled, her hair in Pre-Raphaelite waves. The room smelled of her hair, and of her body, opened and reopened during the course of the day.

'Visit me,' she said in a warm and friendly voice, and held out her arms. She looked dazed and dazzled, her blue eyes warmed like a southern sea. She smiled in complicity. I know you are lovers, we will be his lovers together, love me too.

Well, thought Michael. He could just surf it. Let himself be carried by the wave of adventure.

He went into their new bedroom, stuffed with boxes, some of them full of shoes and vinyl records, and found his sponge bag. He crunched his Viagra into a bitter, tongue-curling paste, to make it work faster. Then he cleaned his teeth to rinse away the bitterness.

The taste of Mrs Miazga's mouth was edged with hormones and a scent he did not quite like. But her huge soft, smooth body was a wonderful maternal harbour. Michael weighed into her, waves rippling around him. There was an excitement about being where Picasso had been, in the folds of flesh still moist from him. Perhaps it was the Viagra kicking in early. Whatever it was, it joined forces with Michael's reluctance to have sex with a woman. Conjoined, they had an unexpected effect. Michael rode Mrs Miazga for forty-five minutes. He did not come, but she did, three times. 'My God, you are super lover,' she said in fractured English. Her fingers strutted pleased up the side of his arm. 'I can tell, you have had many women through your hands.'

Picasso was standing in the doorway. He chuckled approvingly. Much of the time his eyes were kind, as now. 'My big friend loves life,' he said proudly. He mimicked the gesture of Madame's fingers, and strode forward. 'Now I show you,' he said. With no manners, Picasso pulled Michael away from her. He grinned down at the woman. 'I am back,' Picasso said, his teeth bared, and she looked up at him adoringly conquered.

Michael was relieved to be relieved. He went downstairs, clothes draped over his arms, showered and sat in the sitting room. He poured himself a whisky and ate crisps. For the next two hours, the man he loved was in the next room fucking someone else. Michael turned on the television, low. He was just as alone as when he had been living with Phil. OK, you learn. Having a lover, husband, whatever, does not stop you being alone.

Michael had power. He could get rid of Picasso whenever he liked. He could walk in there now and banish him, leaving Marta stranded and shocked.

Except that that had not been the deal. Picasso had given him what he asked for in exchange for life. And why did Picasso want life so very much?