When she first saw him it was purely by chance.

It was a cold day with a sharp wind and a bite in the air and Rose didn't have much to do.

That was an occupational hazard of dimension jumping, it turned out. Less racing against the clock to save the universe from imploding, and much more sitting around wondering what to do in a world where she didn't have a job or anyone she knew.

This universe certainly seemed to pose no immediate threats to her life. No killer environment, monstrous creatures or hostile natives, so far. It was all rather boring. In fact, if she didn't know any better, she'd think she was in her own home world.

She wasn't, as there were plenty of little clues hinting at this universe's otherness, the most obvious being that she had landed in New Amsterdam, in the State of New Amsterdam, America.

She had half expected zeppelins in the sky after that, but apart from a few discrepancies with historical details that she could spot (there were probably more, but she didn't exactly know enough about American history to notice) it was all startlingly similar.

Except, of course, for the aliens. After everything that had gone on back home, her world had hardly been blind to their existence. Here, though, the only allusions to extra-terrestrial life seemed to come in asteroid probes for signs of water, crackpot UFO sightings and Sci-fi movies. It was her old world, before the Doctor had come crashing into her life.

And that frightened her a little. It had always been distantly comforting to think that, in whichever universe she landed, there was a chance that somewhere out there was a planet like Gallifrey, and just possibly, someone like the Doctor. The possibility that no alien life existed here at all was strangely lonely.

So Rose had hit the libraries. Partly, it had to be said, for their free toilet facilities and heating. Since she had a limited supply of currency (thankfully the pounds sterling she had exchanged for dollars had been accepted after a brief, tense inspection), she had to conserve funds as long as she could; she was not looking forward to sleeping rough.

But mostly she went for research. She had searched all the public records and newspaper archives she could find, scanning them all for references to any strange or unexplained events. She had peered through magnifying glasses at old, blurred photographs, searching for any face reappearing in an era not its own. She had even questioned every archivist and librarian she had met about any City records or private libraries where more records might be kept.

As a result, the denizens of various libraries all over New Amsterdam were under the impression she was either a PhD student of the paranormal or a conspiracy theory nut job. Rose didn't correct them.

It did have the drawback of sometimes attracting hostile attention.

Rose had ignored the burning pair of eyes boring a hole into the back of her neck for as long as she could, but by three thirty on that particular afternoon, she could stand it no longer. It was a Sunday, so the library was closing in half an hour anyway. Sighing loudly, she made a note of the page she'd read to and stood to shelve the tome of collected volumes of the Daily Bugle dating from the fifties, studiously ignoring the glowering librarian as she passed. The woman sniffed, loudly and deliberately, and Rose slowed despite herself, her shoulder stiffening.

I do not smell, she reminded herself fiercely. She was staying in the cheapest, most basic hostel she could find, with and owned quite possibly the most sparingly used bar of soap in this universe's history. She was also wearing the same t-shirt for the third day running (and as such hadn't visited this particular library for a few days). But she had taken great care to ensure that, at the very least, she didn't smell like a hobo.

Still, after Jackie's pampering and the TARDIS' endless supply of home comforts, she had never before been so lacking.

"All right, all right," she grumbled, to the librarian's evident satisfaction, and headed to the exit with her head held high.

Outside it was colder than she'd thought it would be. Only her determination not to give her petty enemy the satisfaction of knowing she had nowhere else to go prevented her from turning around again.

Instead, she stamped her feet, pulled her thin jacket closer around herself and blew on her hands. There was a deli round the corner, she remembered. The owner liked her accent and had given her a large discount the last time she'd visited. Perhaps he'd be feeling generous again?

Looking back, Rose always thought it said something about her, that she was drawn along the current of fate by the urgings of her stomach.

One chatty barista, some flirting and a couple of dollars later, Rose emerged on the street, clutching her prize, a large bagel.

As she leaned against the wall to eat it, her eyes wandered to the Science Museum across the street. A large banner advertised a series of free public lectures on Theoretical Physics taking place that afternoon, listing the speakers in smaller print she couldn't be bothered to read at that distance.

Rose blew a strand of hair out of her face and considered.

Since meeting the Doctor, Rose had come to learn that 'Theoretical Physics' could mean all manner of things, from Chaos Theory, to Dark Matter and even Time Travel.

Most of it, at least as far as her species' research went, was way off point, he had said. But he had smiled fondly as he said it, clearly enjoying their stubborn determination to hammer their heads against what they didn't have the technology to understand.

"But you'll get there some day. That's what I love about you humans. You never stop trying and exploring. Bless."

Rose amused herself for a moment, thinking what those professors and scientists would give to have a conversation with the Doctor. She laughed. Perhaps she could give them some pointers.

A chivvying finger of a wind pierced the slight gap between her jacket and her jeans, making her shiver.

If nothing else, she decided, the museum would be warm, and it would be open for at least another hour as the last lecture of the afternoon wrapped itself up. Mind made up, Rose hoisted her battered rucksack further up her shoulder and headed inside.

She arrived just in time to hear the Chair announce the last lecture of the day.

"Dr John Smith of Cambridge University.

There was a polite round of applause, but Rose was hardly aware of it as she stared, transfixed.

There he was, just as she remembered him, down to the brown, pinstriped suit, messy hair and wildly gesticulating hands.

He bounced onto the stage like a hyperactive puppy, enthusiastically holding forth on whatever it was he was lecturing on. Rose honestly couldn't hear anything past the achingly familiar sound of his voice, pattering along a mile a minute, with occasional pauses to consult a white board behind him, or to draw messy trajectories of something.

It was him.

It was the Doctor.