Note: This was originally written for a story challenge on another site, inspired by this picture:
http/ Wharf. San Fransisco. July 2004. He'd been to this place many times now and it was always fascinating to see how it changed from visit to visit. There was a man sitting on the bench, oblivious to him, perhaps caught up in his own grief or simply enjoying the beauty of the day. He tried to just sit back and enjoy the beauty of the day. But all he could think about was the fact that she would probably not be there.
The last time she'd met him, she had told him that she would meet him again here under this tree. At this point, that was a year ago in her time and ten in his. The last time they'd met had been just after his visit there to investigate Faction Paradox, just before everything had started really going wrong. After that, he'd had to spend his time on the run and then--he simply forgot. He'd forgotten a lot of things. And then, when he'd finally remembered, there had been many other things he'd had to take care of. And now that he'd finally had a chance, she never seemed to be there when he was. He had always wondered whether the universe had it in for him, and now he was beginning to be certain of it.
Maybe she was still at the hospital working late. Maybe she was helping UNIT USA on some mission or other--the Doctor was fairly sure this was after she'd joined. Or maybe she was out watching a movie with some friends, or with a man, a human man. She probably wanted to see him again, if she hadn't changed too much since the last time she'd met him. But the Doctor had never left her any signal device or anything that could help her reach him. He thought he knew the course of her future, had forgotten how flexible history really was. So when he went she had no way of knowing he'd be there, and vice versa. Maybe every now and then she would spend a few hours sitting on the wharf waiting for him, slowly beginning to think there was no hope he'd show up--why would someone who had been to countless planets and travelled with countless friends remember her, who he'd only met a few times?--and then she left, alone. And then, a few hours or only a few minutes later, the TARDIS would show up and he'd wait for her.
She didn't know what he knew. She didn't know that before long they would never be able to meet again. He wished could have a chance to say something to her--he didn't know what, as long as it was something--and tell her how much she'd meant to him. But he started to realize there was no hope. There was a planet that needed saving, somewhere, and Julia was probably getting impatient. All he could do for now was let the past take care of itself.