My aunt was quiet a long moment, and then she said, in a voice I had never heard her use, I told you to stop looking because I made a promise a long time ago, but you have found her now, so let me keep a different promise and finally tell you the truth.
I braced for something frightening. And then my aunt told me who the woman in the window was, and it was not frightening at all. It was the kindest thing anyone ever did for our family.
The woman watching our house across all those years was your mothers dearest friend, and she was keeping a promise she made at your mothers deathbed.
My mother died when I was very small. I barely remember her. What I did not know, until that phone call, was that in her last days she had asked her closest friend to do something enormous. She asked her to watch over us. Not to raise us, my father did that, but to keep an eye, from a distance, and to step in quietly if we were ever in trouble, so that my mother could go knowing someone who loved her was still watching her children grow.
And the friend did exactly that, for years. She owned the house across the street. When she grew older and moved away to be near her own family, she still came back, again and again, and stood in that upstairs window, and watched us play in the yard, and made sure the children of the friend she lost were all right.
My father knew. He had always known. He let her watch because it comforted him too, knowing my mothers love still had eyes on us through the woman she trusted most.
The last photograph, taken a few months before my father died, was her final visit. She came, my aunt believed, because she had heard he was failing, and she wanted to see the children one more time while their father was still living, and to keep her promise to the very end.
My aunt had been sworn to secrecy because my mother had wanted it that way. She did not want us to feel watched, or to grow up under the weight of it. She only wanted us safe, and loved, from a distance, by someone who had loved her.
The woman was still living, it turned out, very old now, in a care home two counties away. I drove out to see her the next week. When I told her who I was, she wept, and she held my face in her two hands and said I had my mothers eyes.
She told me stories about my mother I had never heard, a whole afternoon of them, the mother I could barely remember made real and laughing again in that old womans voice.
I go and see her often now. The woman in the window was never a stranger, and never a shadow. She was my mothers love for me, given a face, keeping watch across thirty years so I would never truly be without it.