Disclaimer: How I wish I owned them! Anyway, I don't; they're the property of the BBC.

Chance Encounter

Donna had gone shopping. The Doctor found himself unable to understand why Donna had gone shopping in the 1930s - she said she needed shoes, and he had thrown open one of the TARDIS's cupboards and shown her hundreds of shoes.

"In your size, too," he had said, picking out a pair of red sandals at random.

She had thrown them back at him, and had informed him she was not missing out on the chance to buy authentic 1930s footwear. And because he could not face the argument, he had given her money and told her to be back by dark, and had let her go.

After some time spent tinkering with the console, which had been emitting a strangled beep on occasion, he gave up and stepped outside into London, 1932.

It turned out to be a bright, sunny day, and the Doctor's spirits lifted as he strolled along. He had parked the TARDIS in an unobtrusive alleyway off Piccadilly Circus, and after considering the merits of heading towards Westminster to see what was going on in Parliament, he decided instead to wander into St James's Park. It was busy with people - families, with small children; courting couples; businessmen in top hats.

The Doctor flung himself down on the grass and lay back, hands behind his head, watching the clouds drift by above. He was, suddenly, a lot less annoyed with Donna.

He lay there for a while, letting the day float over him, listening to the conversations as they passed by.

"Alone, my dear! All the way to Ireland from America. Quite extraordinary."

"Not right for a woman. Flying. Whatever next!"

"So then I said to Esme, Esme, I said …"

"David, no, don't do that!"

"And Esme said …"

"Retire! Why should I retire, Tilda? I enjoy my job. It gives me an income."

The Doctor sat up, the day suddenly in sharp focus. He knew that voice.

"Darling, you're fifty. You should be settling down somewhere."

"And do what, exactly?" The tone was sharp. "I'm a nurse. I've always been a nurse. I like being a nurse."

The Doctor was on his feet now, looking around. Coming towards him, two ladies in plain but smart coats and neat hats. His face split into a broad smile, and he felt even more kindly disposed towards Donna Noble and her shopping habits.

The ladies were coming closer, still embroiled in their discussion. "But you should find a nice husband, dear."

"I had a husband, Tilda," came the reply. "And there was never …"

"Nurse Redfern," said the Doctor, as the speaker stopped, gazing at him with mingled surprise, and shock, and memories in her expression. "Nurse Redfern!"

"Joan?" said Nurse Redfern's companion. "Do you know this … gentleman?"

Joan Redfern, older now but still beautiful, still coolly elegant, stared at him. "I … yes … he taught at school. Erm … Tilda, Doctor … John Smith," she managed to get the name out. "Doctor, my cousin Matilda Armstrong."

"Delighted," said the Doctor, feeling that he was indeed delighted.

"What do you teach?" asked Matilda Armstrong, adjusting her handbag.

"History," said the Doctor.

"Fascinating subject," Matilda said. "Doctor Smith, Joan and I were about to take tea. Perhaps you would join us?"

"Oh, I'd … if it's not an inconvenience," the Doctor said, "I'd love to. Tea. Brilliant."

Matilda raised her eyebrows at his enthusiasm.

"Please. Do join us," Joan said.

He fell into step by her side.

"What are you doing here?" she asked, quietly.

"Passing through," he returned.

"But why here? Why now?"

"Why not?" asked the Doctor. "As good a time as any." He glanced sideways at her. "There's no alien attack planned, if that's what you mean; at least, not that I know of. Not this time."

Matilda Armstrong had stopped walking to talk to someone else, and Joan sank down on a nearby bench.

"I'm sorry," she said. "I hadn't expected ever to see you again … and you still look like him."

"I'm not him," the Doctor said. "That hasn't changed. If you want me to go, I can … if you want."

"No." She sighed, and shook her head. "No. Time has taken away some of the pain, I find." She looked at him. "How long has it been for you? You haven't aged a day."

He ran a hand through his hair. "We, erm, Time Lords don't age, exactly; it's a biological thing … six months. Or a year and six months, if you count the year that didn't happen. On balance I'd rather not count it. So, six months."

"And Martha? How's Martha?"

The Doctor thought back to the last text message he had had from Martha Jones, a short, fluently abbreviated missive informing him that she was going to do some work with Torchwood. "At home," he said. "She left me."

Joan laid a gloved hand on his. "I'm sorry."

"Sorry? Nah, don't be sorry. Her choice. Best thing. Anyway I'm not alone, there's this girl, Donna - she's shopping. That's why we're here. Shopping."

"You're shopping?"

He shook his head. "She's shopping. I was watching the world go by. 1932. Good year. Nothing much happens."

Joan gave him a severe look. "Somehow I rather think you saying that will mean something will happen. Don't things tend to happen around you?"

"Not always," protested the Doctor. "Often. But I have been known to visit a place, and leave it, with nothing whatsoever happening." He grinned at her. "It's good to see you. What have you been doing all these years?"

She folded her hands over her handbag. "I volunteered, during the war. You knew it would happen, didn't you?"

"Yes."

"And couldn't you have stopped it?"

"It wasn't my war," he said. "It happened. The thing about time travel, the crucial thing, is that you never cross your time lines. Never try and change things. When you do …" he shuddered, remembering the day Rose Tyler had saved her father's life, "when you do, bad things happen. So no, I couldn't stop it. But you got through."

"I got through. So many didn't. All those boys, Doctor, all those boys."

"Tim Latimer survived," said the Doctor.

Joan smiled. "He did. He keeps in touch, bless him. A sweet man. How did you know?"

"Martha and I looked him up, after we left you. He'll live to a ripe old age," said the Doctor. "Which he shouldn't know, by the way. And then, after the war?"

She talked, telling him about the school she now worked in, the boys she was looking after. She seemed, he thought, happy - content at least.

"I'm visiting Tilda as it's the school holidays," Joan said. "She thinks I need a husband."

"I heard," the Doctor said. "Evidently you disagree."

Matilda, her conversation finally at an end, approached them, and Joan rose. "I do," she said.

They headed towards St James's Street, making empty conversation about the delightful weather and Amelia Earhart's achievement in flying across the Atlantic. Installed in a tea-room, with cups of Earl Grey and - to the Doctor's delight, dainty little cakes - Matilda turned her attention to him.

"So, Doctor Smith," she said, "you teach history."

He swallowed a mouthful of cream cake hastily. "Yes. History."

"And which university did you go to?" Matilda asked, picking up her teacup daintily.

The Doctor's mind went back to John Smith, the unassuming history teacher. The chameleon arch, for whatever reason, had decided that Smith had been to Cambridge. "Caius, Cambridge," he said, accordingly.

Matilda nodded, satisfied with his credentials, and they talked about Cambridge for a while. He found that Matilda Armstrong, like many people, was a snob, and name-dropping a few famous Cambridge alumni who he had met (just not while studying at the university) seemed to keep her happy. Joan put in a few words, here and there, but her good mood had diminished.

After tea they stepped into the bright afternoon again. The shadows were lengthening, and the light had taken on a mellow golden tone.

"We must be heading home," said Matilda.

Joan took her hands. "I have so much to catch up on with the … with Doctor Smith," she said. "I'll catch a hansom cab, and be home by supper. No, Tilda," she said, in response to her cousin's protests, "I insist. I don't need a chaperone."

The Doctor, impressed despite himself, proffered an elbow. "Nurse Redfern?"

She took his arm. "Doctor. Where are you staying?"

"This way."

They walked off, leaving Matilda Armstrong thunderstruck outside the tearoom.

Once they had rounded the corner Joan let go of the Doctor's arm, and laughed briefly. "Goodness. You are a bad influence, Doctor."

"That's me!" he grinned. "Very bad influence. Corrupting, some would say."

"You're completely different," said Joan. "I expected … I expected you to be more like him."

"I told you; all that he was, I can be," said the Doctor. "He's not really dead, he's in here." He tapped his head. "All his memories, those were just a story; but all his feelings - those I remember."

Joan sighed. "Such words, Doctor. You're more of a charmer than he was."

He smiled down at her, and stuck his hands in his pockets. They walked in companionable silence, surrounded by the lights of Piccadilly and the bustle of people.

"Where are we going?" asked Joan, after a bit.

For answer, the Doctor turned off the street and led her down towards the spot where he had left the TARDIS. It stood peacefully, reliably, and inconspicuously; and in front of it was a pile of shopping bags and an irate Donna Noble.

"Where the hell have you been?" she said. "I've been waiting here half a bloody hour. And you were the one what said be back by dark."

"It's not dark," the Doctor pointed out. "And you're back. And so am I. And that's a lot of shopping. A lot of shopping. I know there's space in the TARDIS, but really … a lot of shopping."

Donna shrugged. "D'you know how much money you gave me?"

The Doctor elbowed past her, and unlocked the TARDIS. "Go on. And don't leave shoes all over the floor."

Donna pushed past him with most of her bags. The Doctor turned, and looked back at Joan. "My blue box," he said.

She came up to it, and laid a wondering hand on its wooden side. "I don't think I understand it."

"Ah, she's incredible," said the Doctor, cheerfully. "Come inside. C'mon, have a look. She won't hurt." He held out his hand. "Come on."

Joan took a deep breath in, and nodded. "I will."

He let her go first, and picked up the rest of Donna's shopping before following her in and closing the door.

Joan was standing, lost in silent astonishment. The Doctor waited for her to say something - he was hoping it would be something more original than "it's bigger on the inside!" - but she seemed incapable of speech.

He dumped Donna's bags by the doorway through to the corridor and shrugged off his coat. Joan was still gazing, her eyes now fixed on something hanging from the ceiling. He followed her gaze, and cursed inwardly.

"That's nothing," he said, crossing and swinging the chameleon arch out of the way. "Scrap. Should get rid of it."

Joan touched the wall nearest her, and brought her hand back quickly. "It's warm," she said.

"She's alive," said the Doctor, running his hand along the console. "This is my TARDIS - the best ship in the universe."

"So he says, but he never explains why," Donna put in, coming into the console room in a green dress. She twirled. "What d'you reckon?"

"Very green," said the Doctor.

Donna subsided in a swish of emerald. "So, you going to introduce us?"

"Joan Redfern, Donna Noble," said the Doctor, abiding by human customs because it was the easiest option. "Donna," he continued, waving a hand towards his newly-emerald companion, "is travelling with me. Joan," he said, "is …" he paused, trying to work out exactly what she was.

"An old friend," said Joan, filling the gap.

"How old?" demanded Donna, sitting down by the console and folding her arms.

"Eighteen years," said Joan.

"Six months," added the Doctor. "We bumped into each other in the park. And now I'm showing her the TARDIS." He held out his hand to Joan. "There's much more of her."

Joan shook her head. "No. No, Doctor; this is enough. I should … I should get home."

Donna, taking the hint (and the rest of her shopping) disappeared again. The Doctor looked beseechingly at Joan.

"Really. I'd love to show you the TARDIS. I'd show you more. You'd adore the gardens on Nebula Five. And the starstorms out beyond the Fifth Galaxy. I could take you to meet Florence Nightingale. Queen Elizabeth! I still need to find out why she wants to kill me, anyway." He gave her his best pleading look. "Travel with me."

She came up to him, and took his hand. "No, Doctor. Thank you, but no. I am happy with what I have here - I don't want to see the stars."

He met her eyes. "All right."

"I wanted a long life with John Smith," Joan said. "My John Smith. He was a good man."

The Doctor nodded. "Yes, he was. A better man than me. But he couldn't stay. Even if the Family had not come when they did - I'd have been gone in another few weeks. I'd told Martha to open the watch after three months."

"You enjoy this life," said Joan.

"Bouncing from planet to planet, meeting extraordinary people, seeing things nobody else has seen? Impossible not to enjoy it!" said the Doctor.

"And is it better than what you gave up?" asked Joan, softly. He let go of her hand, and began setting coordinates, moving round the console. "Is it? A family, a home?"

The Doctor paused, and met her eyes. "I had a family," he said. "And a home. But they're long gone, now. Gallifrey burned, and I am the last of the Time Lords."

She broke the eye contact first, fiddling with her gloves. "I'd better go," she said at last. "Will we meet again?"

"I can't predict the future," said the Doctor. "Well, that's not strictly true - I don't know what happens in your future. Not what happens to you."

Joan lifted her head. "If you happen to be passing through, again, look me up."

He nodded. "Absolutely."

She smiled. "I'm glad we bumped into each other - Doctor. I think I may have been always wishing for John Smith. Now I shall remember him and stop grieving."

The Doctor grinned back at her. "Joan Redfern. Quite a lady. You're sure you won't come?"

"I'm going, now!" exclaimed Joan. "Before you badger me into it. You, Doctor, are perfectly incorrigible."

"I am. Incorrigible. And brilliant, don't forget brilliant."

She shook her head, and walked briskly out of the TARDIS. The door closed behind her, and for a moment he stood and looked at it. Then he spun on one foot, pressed a button, pulled a lever and listened to the familiar sound of his ship in flight.

"She's gone, right?" said Donna, appearing again in her new green dress.

"Back to her life," said the Doctor.

Donna sat down, and patted the seat next to her. "C'mon. Get her off your chest. Tell me about this Joan Redfern."

The Doctor took the seat, and put his feet up on the console; and began to tell Donna of 1913, and of a man who never really existed.