Chiswick High Street has two Starbucks, a Caffe Nero, and a dozen other coffee shop/restaurants with outdoor seating. Lovely places to sit and while the hours away watching the people of Chiswick wander by. It's a charming High Street, and almost everyone in Chiswick ends up here at least once a week.

The man in the brown suit strode restlessly up and down the High Street three times before he finally settled on the Starbucks opposite and a little bit down from Turnham Green Church. He settled down outside it, with a large hazelnut cappuccino, stuck his long legs straight out in front of him, and stared morosely into the crowd.

He was a good-looking man, in a quirky way, but today looked like he didn't quite fit in, like he never quite fitted in anywhere, but then again, lots of people looked like that in London. It's the home of misfits and lost souls. Maybe it was his eyes that disconcerted people. In them, you could see he knew the answers to a million questions you'd never think to ask. The occasional girl – or boy – more perceptive than the rest, glanced at him, and knew that a day with him could transform their lives - or destroy it.

But today he looked like he wanted to be alone, frowning darkly over his coffee. Life flowed around him, and he stayed still, watching it all.

He'd tried to stay away. He really had tried. He'd gone to have another try at a Victorian Christmas – which had only reminded him he was travelling alone, whilst even fake Doctors had a companion. He had gone to the Glorious Seven Moons of Tabor Major, guaranteed to wipe away your troubles (it said so on the brochure) – until he had landed on the Third Moon, made of ice, and heard a familiar voice complaining that it was 'bleeding freezing!' so clearly he'd turned to look. He'd had a trip or two with someone new – but it had never quite been the same. They'd been nice, and polite, and didn't argue and didn't make fun of him and weren't difficult and let him make decisions, and they had left him feeling – empty. His restlessness was different these days – he wasn't travelling to discover. He was travelling to stop himself going somewhere.

And now he was sitting here, in the one place in the universe he really shouldn't be, waiting to see the one woman he really really should not be seeing. He sat in the sun in Chiswick High Street, telling himself he was there only to check on her safety, knowing he was lying. He was there because he needed to see her. So he sat, and sighed, and let his coffee go cold and pulled at his hair, and argued with himself, only occasionally out loud.

Until a woman stopped front of him, hand on her hips, smiling quizzically down at him.

"What are you doing here?" the woman (who looked a few years older than him, but very pretty) demanded.

"What are you doing here?" he retorted, surprised.

"I live in Ealing." Sarah Jane Smith replied, pointing her thumb over her shoulder. "I gave Clyde and the others a lift into Chiswick – he's catching a bus back to Hounslow for the day. Show Rani and Luke his old stomping grounds."

"Clyde? Luke?" he said vaguely. Sarah Jane sat down opposite her oldest friend. "Clyde is Luke's best friend, Rani is the girl across the road, and Luke – well, Luke is my son." she told him, suddenly glowing with pride.

"Oh yes, long story, you said." he replied, leaning back in his chair, and watching the children leave on the double decker across the road.

"Yes, well, if anyone has time, you have."Sarah Jane said firmly. "Buy me a large vanilla mocha, and I'll catch you up on my life lately." She leaned forward, and whispered mischievously. "It's really quite exciting!".

To give him his due, he listened intently to her story. He laughed and gasped in all the right places, and asked intelligent questions. But his intense dark eyes occasionally wandered over to the street, looking for a mane of red hair, for sad, searching eyes, listening for a raucous laugh. Sarah Jane watched him, this man she had loved for so long, once with a passion, now in a deep and abiding way, his life running and twisting through hers like a scarlet thread.

"I teach a writing class too, on the side." she said. Her story had trailed off a long time ago, and he had fallen silent, leaning forward, elbows on his knees, hands clasped, eyes staring into the crowd. Once he had heard a laugh, and turned suddenly, only to see it came from a short brunette, giggling into her phone. He had caught a glimpse of red hair, but it was a cool, elegant teenager. Each time, he had felt a sudden tightening in his stomach, and each time, the mixture of disappointment and relief had been sickening.

"Over there." Sarah Jane nodded her head to gesture across the street. "In the school, a class for adults."

He looked up at her and nodded, then stared back down the street. He was no longer bothering to hide his abstraction from her.

"I've got a very talented class". She continued, watching him intently. "And my favourite pupil is called Donna."

His head snapped up suddenly to face her, his eyes burning.

"I got your letter." she said softly. "I know what the danger is."

"You were just supposed to keep an eye on her!" he hissed.

"Did you expect me to do that from a distance?" she snapped back, though calm. His anger never frightened her. "Any of us?"

"If she remembers....what do you mean, any?" He had that 'humans-have-confused-me-again' look on his face.

"Martha has taking to walking around this area a lot. Thinks it's pretty." Sarah Jane said, sipping her coffee, and staring across the street to the Gothic church. "Jack has the CCTV in this area on a permanent screen in Torchwood. And Micky – goodness know what Micky does, but he does seem to show up when needed. Nice boy, that"

"You can't." he said, breathing raggedly. He stood up, towering over her. "None of you can – you were supposed to just check on her occasionally, check she was ok.."

"Ok?" Sarah Jane snapped. "You took this woman who thought she was worthless, that her whole life was pointless, and you made her brilliant."

"She was always brilliant." he said sullenly, collapsing down into his seat, legs stretched out in front of him.

"You made her see she was brilliant. You gave her a purpose and a life. You gave her the universe – and then you took it all away. That was so cruel, can't you see? It's almost worse than if she had died!"

"What else could I do?" he cried out, mindless of the staring people hurrying by. "If I'd left even a trace of a memory of all the amazing things she'd done, she would have died right there, in my arms. Anything ... anything was better than that. Even – losing her."

"I'm sorry." she said quietly. She looked up. "Why are you here?"

"I just had to see. To check. To make sure I did the right thing." He turned to her. "She won't see me. I won't say anything to her. I won't take the risk of triggering her memory, I just want to make sure she's alright."

"She's not alright. She's missing a huge chunk of her life and the better part of herself, and she knows it."

"I gave you orders." he said darkly, then looked into her mutinous face. "Sarah Jane..." he said pleadingly.

"She came to me." Sarah Jane said shortly. "I intended to keep my distance, I really did. We all did. She came to my class. I almost turned her away."

"Why didn't you?"

"Because I recognised that look in her. She wants to be more than who she is. She needs to be more. She wants someone to tell her she's brilliant. She wants to believe she's brilliant. I know how that feels. I was like that once, before I met you."

"She came to you?" he said, puzzled.

"People you know tend to pull together. Did you know that? It's like you're a huge magnet, and you magnetise us, and then we're drawn together. Your companions and friends bump into each other all over the place. And so do your enemies." she told him. His face was stunned. He'd never really though about what happened to them – afterward. He always assumed they went back to their old lives, or built a new, safe one. He'd always just assumed they went on – he never went back to check.

After all, Sarah Jane went on the same as before. And then ... then it turned out she'd changed direction. Become a hero of Earth herself. And Martha – she'd changed completely – and so had Jack, rebuilding Torchwood to honour him. How could he possibly think that Donna would have remained unchanged?

"I .. magnetised...her?" he asked dubiously.

"Well, in the past few weeks, there's been a slight upsurge in alien activity around here." Sarah Jane said, pulling out a pad. "Nothing much so far – a few probes, lights in the sky, a funny smell outside the library – though that's probably the drains. Although there is something funny in the library cellars. Back to that later. I suppose it could be my fault – Ealing is just down the road, but somehow, I don't think so."

"I magnetised her?" he repeated, still seeming to have trouble grasping the concept.

"I have to know." Sarah Jane asked, quietly. "Why did you come back for her? You've never done that before"

"I've come back."

"When called. Never of your own accord." She looked up, as he stood up over her, hands jammed deep in his pockets, a uniquely alien look on his human-seeming face. "Why have you come back for her?"

"Sarah Jane?" someone asked, from beside him. He looked around – and stopped breathing.

She was there. Donna Noble. His Donna.