Jimmy had the grace to look chastened. He gripped Michael's arm. 'Just my little joke,' he said, and left. Camp will always let you down.

When they had all gone, Picasso was slow and well fed, like a bullfrog. He put a hand behind Michael's neck and said 'I like being with you. You are useful.'

Tender words. 'I keep you alive,' said Michael.

'You will find when I am being good and you have not made me angry that I am good to you.'

The thought arrived whole and clear and quiet. This is love, and this is adventure. But this is not good for me.

Michael had assumed that love was always in one's interest. If love was a stone that rolled you naturally home, it must be a good thing. The idea that love could smash as well as build a home or roll you further and further from your self had never occurred to him.

Michael's entire flat became a workshop: a pottery wheel appeared in the bathroom, with sacks of clay. When he was not painting or computing, Picasso was sawing wood from pallets he had found at Camden market. He would scoop up scraps of fabric, a baby's shoe, or the skull of some small rodent picked clean. Everything entered the maw of his art and was taken back to the flat to be used.

Adoring women arrived. They no longer wore X-Files T-shirts and Camden nose rings. They were smart, bright young gallery assistants from Notting Hill or Bond Street. They wore slim black slacks, graceful shoes and medium-length, artfully tinted hair which they tossed from time to time to indicate fascination.

'Hello, Michael,' the gallery assistants would beam at him when he arrived from work, as if genuinely pleased to see that their fascinating new artist lived with another man. 'I'd better be going,' they would offer, standing up after a decent interval.

Picasso kissed their fingers, between the knuckle and first joint. 'Oh, but you will come back, I hope.'

Amanda, Diana, Jill, Cecilia; apparently they did come back, judging from the state of the bed linen. Michael gave in and began to sleep on the sofa bed in the living room. His headaches started coming regularly. When do you get headaches, Michael?

When you're angry.

Michael came back from going to see In the Company of Men alone, to find Picasso painting another portrait of him: this time as a weeping clown. Was Michael flattered? He was certainly enveloped, and perhaps being digested.

'People call idiots the Clowns of God.' Picasso touched Michael's nose with the tip of the brush handle. 'Clown,' he pronounced him. 'You are in an unequal contest with God. This is foolish, but inescapable. I learn new things from you, Michael. I did not know that the privilege of saints was to fight with God. Most of us don't even touch Him.'

Picasso painted either in great easy sweeps, or impatient jabs and lunges that left the canvas or the previous layer of paint showing through in streaks. This was an impatient painting. Picasso had scrawled tears in the jagged, staring diamond eyes.

The next night Michael came home at 6.30 to find Mrs Miazga beside herself in what was now Picasso's bed. She was red again, but now it was from irritation. Perhaps she had found evidence of others. She looked miffed when Michael stumbled in to fetch shorts and a T-shirt to wear in the house, unconsciously imitating Picasso. They both stared, wishing the other gone, wishing themselves gone, wishing him gone.

'I'm sorry,' said Michael, coldly. 'I didn't know you were here.' She drew the sheet up higher. She shrugged, but could only just bring herself to say, 'It's your house.'

Michael found a private corner in the sitting room in which to undress so he could shower. His towel, he remembered, and his bag of toiletries were still in the bedroom. Damn. He marched back into the bedroom, his trousers wrapped around his midriff.

'Where is he?' he asked, rifling amid Picasso's trash for his own few things.

'I don't know,' she said,, after a pause. 'He left suddenly. I thought you were him coming back.'

Michael blew out air from tension.

'I know,' she said, and swung her feet out from the bed. She fumbled for a cigarette. She sighed. 'If you let me shower first, I could be gone.' She looked forlorn.

'OK,' he said.

He sat in the front room, and looked at the paintings, the new ceramics, the boxes of wood stuffed with found objects. How on earth, he wondered, do I end this?

He doesn't allow other people to end things; leaving must be up to him. It would be hard to have him go, because it was a fascinating story to live beside: to see an artist climb. Especially one who climbs quickly, rather than slowly, painfully, humiliatingly as Phil had done.

It would hurt, to tear Picasso out of his life. At first. But to live with someone you love who does not love you is indeed to eat your own heart. You have to live through cliches to realize how powerful and apt an expression they often are. Michael was eating his own heart out. He would have no heart left.

Michael was good at avoiding decisions, at letting life decide. Life decided. 'Enough,' Michael said aloud. He had had enough. He looked at the paintings on the wall and had two goals: to get Picasso to go, and to save his art.

So the next day, Michael took another long lunch break, and visited Mr Miazga in the flat that had once been his own. Mr Miazga was working alone at his computer, with the resigned grimness of someone unemployed at fifty.

'My wife is not here,' Mr Miazga sighed, 'Is she perhaps at your house?'

Michael tried to think of what would be polite, and realized that nothing would be. 'I don't know. It's possible. I try not to go there.'

'I hate that man.'

Michael sighed too. 'Sometimes I do.'

'You? You love him.'

'The two are not mutually exclusive.' Michael looked at the Zip-drive disk in his hand. Thaddeus,' he began. 'I have a lot of respect for you, and so I am going to ask something that I would not ask from just anyone.'

Mr Miazga kept keying in a program. 'OK. Ask.'

'I want you to redo all his work.'

Mr Miazga sniffed. 'He should make backups.'

'He does. I do. But that won't work.' Michael had rehearsed this next part. 'It would be difficult to explain how I know this, but believe me it is true. Every trace of his work will disappear when he dies.'

'A fault in how he programs?'

'Stranger than that. I can promise you that all his paintings and ceramics will disappear as well. That would be a loss. But, consider if his new work in computer art would disappear as well.'

Mr Miazga shrugged. 'I am not a critic'

'No, thank heavens. You are a creative technologist. So, ask yourself this question. Is he not finding out what can really be done artistically with this stuff?'

Mr Miazga went quiet. 'What are you asking?'

'I'm asking you to rekey in any code he makes. I'm asking you to redo every gif. I'm asking you to rescan every graphic. That way the work will survive.'

'Why?' Mr Miazga turned to him, his bafflement shot through with something genuinely enquiring.

In his shoulder bag Michael had volume two of the John Richardson biography. The books are laced with every existing photograph of Picasso, often in his workshop. Michael opened it at the chapters dealing with the early 1920s. Silently, he kept turning each of the pages.

Michael could see the exact moment when Mr Miazga understood. He jumped as if someone had stabbed him with a pin. 'It's him,' he said and turned to Michael wide-eyed.

'The rules are simple. Whenever he goes back to wherever it is he comes from, everything he has done in this world will vanish.'

Mr Miazga rifled through the pages. 'It… really is him.'

He looked at Michael with something like horror. Then he crossed himself. 'Is this some kind of miracle?'

'I don't really know. We could talk about it all afternoon and still not understand it. Can you believe me, Thad?'