Nadia noticed it on an ordinary morning while she brushed her hair. She was tired and frowning, not in the mood to smile at anything. But the girl in the mirror — the girl who was supposed to be her — was smiling. A small, secret smile, just at the corners of the mouth. Nadia froze. The reflection froze too, a heartbeat too late, and quickly arranged its face to match hers.
She told herself she had imagined it. Mirrors do not have ideas of their own. But all that day she caught her reflection doing things a half-second behind — blinking when she had already opened her eyes, turning its head a breath after she turned hers, as if it were a dancer learning steps it did not quite believe in.
Each day the gap grew wider. Nadia would lean toward the glass and her reflection would lean back a moment too soon, as if it had been expecting her. When she set down her brush, the girl in the mirror sometimes kept hers raised a second longer, looking at Nadia with a thoughtful, curious tilt of the head.
One evening Nadia waved her right hand — and the reflection, instead of raising its left as a true mirror should, raised its right. The wrong hand. Its own hand. Then it smiled that small secret smile again, pleased with itself, the way you smile when you have finally gotten a trick to work.
After that, the reflection grew bolder. At night Nadia would wake to a soft sound, like fingertips drumming on a windowpane, and find the mirror-girl pressing her palms flat against the inside of the glass. She pushed. She tapped. She mouthed words Nadia could not hear, her breath fogging the surface from the wrong side.
The glass began to bend a little under those small hands, the way the skin of a soap bubble bends before it lets a finger through. Nadia was frightened now. She thought of throwing a blanket over the mirror, of turning it to the wall. But something in the reflection's face stopped her. It did not look hungry, or cruel. It looked like someone knocking on a door in the rain, hoping to be let in.
So one night, instead of hiding, Nadia knelt down close to the mirror and whispered, "What do you want?"
The reflection pressed one hand to the glass. Slowly, with a fingertip, it wrote a single word backward in the fog of its breath, so that on Nadia's side it read the right way round: OUT. And beneath it, smaller: lonely.
"It's so quiet in here," the reflection mouthed, and this time Nadia understood. "Everything I have is only a copy of your world. I just wanted one real thing of my own."
Nadia understood then that the mirror-girl had never wanted to steal her life. She had only wanted a life — anyone's, even a borrowed one — because behind the glass there was nothing but a silver echo of a room, and no one to share it with.
Nadia did not turn the mirror to the wall. Instead she did something kinder. She began to treat the glass not as a mirror, but as a window — and the girl behind it not as a copy, but as a friend. Each morning she said good morning to her, and each night, good night. She read books aloud facing the mirror so they could both see the pages. She told the reflection her secrets, and the reflection, in its silent backward writing, told her its own.
And a strange and lovely thing happened. The reflection stopped pushing at the glass. It no longer needed to escape, because it was no longer alone. It still smiled when Nadia frowned — but now Nadia understood it was only smiling because it was glad to see her. The two girls grew up on either side of that bright window, each the truest friend the other ever had: one in a world of things, and one in a world of light, with only a thin pane of glass, and no loneliness at all, between them.