They came every year, more or less on time for Mother's Day, and she displayed them with a mixture of pride and regret. One year it might be a postcard of Monet's waterlilies or a teasingly twee watercolour of a cat stretching a paw into a goldfish pond; another, a vivid aerial photograph of the Nile delta; the next, a picture of some alien lake, carved into a deep, dense stone no larger than her fingernail.
The huge print of Hylas and the Nymphs was pinned up in the bathroom, and never seemed to be affected by the damp. Sun Water Maine hung at the top of the stairs. The postcards she pinned to the back of the kitchen door.
And always, scrawled on the back or squeezed into the border, Mum, much love, River. She had to search for it sometimes, but it was always there.
Amy had a story prepared ('one of my fans... thinks of me as a mother... very touched and flattered...') but she never had to use it, and she was glad of that. It was, she suspected, some sort of Timelord tech, a cloaking device, that made the picture seem innocuous, boring, even, to anyone except her and Rory. It was possible that visitors to their home saw only a white expanse of wall where the Turner view of the Camargue hung. (Amy was sure that it was a Turner, though she never managed to find it in any book or exhibition. It would be just like River to have stolen it before he was famous.)
It would have been too complicated to explain the real story. Which story, anyway?
She's my biological daughter, but she was taken away from me very soon after birth.
True, but depressing, all the worst parts of what had happened, and no way of explaining the good parts.
She's my daughter. I don't see her that often, unfortunately. Even worse.
She's the wife of my imaginary friend. No.
I've known her since we were at school. We've been part of each other's lives for so long, it's almost as if we're family.
But they were family.
Amy would have liked to say, She's my daughter, even if I didn't know that for years after I first met her, she's a professor of archaeology and a convicted criminal, she's amazing and brave and clever and I've been around the universe with her and I'm so proud of her and I only wish I knew her better.
Sometimes, looking at some Old Master's rendering of Rotterdam harbour (priceless) or a working model of the canals on a moon three thousand galaxies away (priceless beyond imagination), she did say it.
In the end, it was enough. It had to be. This ridiculous, endearing succession of artistic watercourses, lakes, ponds, rivers, oceans, was, when it came down to it, only a way of saying in pictures, mother and daughter. Pond and River. Which meant the same thing, when you came to think about it. It was as good a language as any in which to say something that could never quite be explained in any single pair of words.