Here is a non-canonical encounter that many of us would have liked to see. I originally wrote it back in 2007, as part of a longer fic called "
A Tale of Two Doctors" in which Ten and Five get to meet for a little longer after "Time Crash" - long enough for Rose to give Five a little advice on not abandoning past companions:
Bannerman Road, South Croydon, 1982
Sarah Jane was wondering whether to invest in one of those new word processors. They were cumbersome things, and in less than ten years they’d look as antiquated as dinosaurs, but filing copy with an IBM Golfball and Tippex was a great trial. Almost as depressing, in fact, as the country being run by Margaret Thatcher.
She remembered visiting 2003 with the Doctor and marvelling at laptops and the Internet. Time travel was wonderful, but it did have the after-effect of making you discontented with your lot.
She thought she must be imagining things, but she distinctly heard the sound of the TARDIS materialising outside. She rushed into the hall and quickly checked over her hair and her lipstick. Trust him to show up like this, out of the blue, without a moment’s warning. So very typical of him.
“Oh!” she exclaimed in surprise, as the TARDIS door opened and a tall, blonde man in red and white appeared. “You’ve regenerated. How many times?”
“I take it you recognise me?” he asked, gallantly. “Despite the fact that I’m no longer your Doctor?”
“You’ll always be my Doctor, no matter how many times you change!” she cried, hugging him. “How long have we got? Time for tea and biscuits and a bit of a wander down Memory Lane?”
“That would be delightful.” Slightly puzzled, he scratched his head. “You know, it’s the funniest thing. I’d just dropped off my companions and I was pottering around in the TARDIS when the thought suddenly popped into my mind from nowhere - why don’t I look up Sarah Jane? How are you, my dear? Is K9 behaving himself?”
“Better than you are, I’m sure,” she replied, winking at him. “Tell me, what’s the celery all about…….?”
The door closed behind them, and the TARDIS congratulated herself on a job well done.
"To days to come," she whispered across time, and from far away, came the answer:
"Give my love to long ago."