Between its heyday as a glistening urban transport hub and its lonely dotage behind permanent temporary railings, the bus station lived through a middle age of uncomfortable decline. Its guttering buckled and collapsed, brickwork became powder. The grand facades- intended to inspire a rush of civic pride- were caked in pigeon shit, which caught the feathers too. Those of us that worked there were frozen in winter by the intermittent draughts. In those days broken men and women were blown around the concourse with the litter-drifts and occasionally would tell their hard-luck stories over the tea I bought for them in the driver's caff.

They were usually just that of course: stories. A madman in tattered jeans spoke to me in low whispers of the conspiracy that robbed him of his millions, his rock band and wives. The woman with the teacosy hat and the bag of yellowed books insisted I was her son. She wept as reality dawned and I wondered how many times she'd found and lost him. There were those that had a plan- the deceivers with a fortune waiting for them two towns away if they could just get to it; and did I have a tenner for the fare, a fiver then, at least a couple of quid for a proper drink well fuck you, mate. The true stories were the hardest to listen to because they were just like my own, but for the endings. A restless kid, spotted, distracted by the need for crack, told me I was no better off than he was: we were both there every day in the cold, the bus company jacket hadn't stopped the weather clawing my skin.

An elderly transient came to me on an empty night in November. His pristine white hair was thinning to reveal a pinkish scalp. The skin of his cheeks and the back of his hands let blue veins show through. He moved with a brash grace despite his frailty, he was an old David Niven playing a young Roger Moore. He hunched over the formica stirring the tea I fetched for him and smirked when I asked if he had stories worth telling. His calloused hands, he said, were the result of scrambling over the lava flows before the Earth had cooled. I marvelled at the scale of his delusion as he recounted battles he had had before time was quantified- a mastodon that bested him, a pterosaur he'd slain and consumed. He described a feud with Poseidon that caused him to flee the coasts and explore the interiors of great continental landmasses. His eyes seemed countless years distant as he spoke of watching life drag itself from the oceans, of his amusement as the apes learned to talk. He saw Alexander claim all Asia after Darius' fall, tutted scornfully when Columbus claimed discovery of a new world that really was as old as all the others. He had warmed his hands on the flames that took London.

His histories were so rich and tactile that I chided myself for noticing the incongruities that only trouble the sane. How could he claim to have charted the relentless march of natural progression before Darwin had ever named it, and still tell of waking on the sixth day to a world of possibilities? And if he remembered the kindly face retiring to rest on the seventh, then how could he also have watched Thor stomp across the tundra in search of Utgard? So I asked him. The storyteller answered that the world had been an ambitious undertaking, and that creations need not be mutually exclusive. Besides, there were many In the Beginnings and just as many Ragnaroks.

My laughter was an expression of the simple joy in a tale well told, but it seemed to mark me out as a philistine- the man threw on his coat and made to leave. I worried about hurting the old boy's feelings and tested the ground with a teasing question: what was the secret of a life that outlasted empires? Scoffing, he said I wouldn't even be willing to take the first step.

'Try me.' I said. The man's fantasies had been intricate. I was hooked enough to want to hear the logic behind his immortality. He brought his face close to mine and suddenly it seemed the years had dropped away from him. A powerful urgency filled his eyes and his voice.

'Pull yourself free of the river and stand on the bank, watch it flow past you.' His stare was cold, he didn't smile. 'Do this, and you'll be there at the first, where the sun is drawing us in from the dark, setting us to spin, uniting disparate particles. You'll see the last, where the flame that lights and warms is swelling, taking back what it gave to us in a fire of destruction.' His words unsettled me. There was a mania here that wasn't present before, though his eyes remained dead calm.

'And how...?' I began to ask, stepping backwards uncomfortably.

'These currents that drag us through time,' he said, putting on his hat '...they are sentimental. Your love for the things and places that comfort you, the people who hang on your words- these things are woven through you and you through them. Leave them and never look back and be free. If you love anything, let it fall to the ground and shatter.'

For a horrible moment I thought of Jane waiting up for me on the sofa in our home, of Connor already asleep. The thought of never returning to them was absurd and terrifying, yet I remembered all the lonely walks I'd taken after fights and the bags I'd packed before calming down. I was about to ask the old drifter what his hideous theory had driven him to abandon, whose heart he had broken with this madness; but before the words reached my lips the aged figure had turned and was at the door.

'I love my wife and son,' I called after him, inexplicably '...I'd never leave them.'

'Then good for you,' he said warmly, smiling over his shoulder, '- you can live a life, be happy and die.' He let the glazed door swing shut behind him, and I watched through the steamed-up windows as he ambled back into his huge dark outside. I rushed home.