Disclaimer: JK Rowling owns the rights to the Harry Potter stories.
She doesn't know what she looks like. At birth she was already changing, hair shifting rose, violet, turquoise, the color of a scarf, the floor, anything her infant eye took in. She asks her mother, but she shakes her head -- she was tired, and Tonks changed soquickly. Anyway, they moved a lot those first couple of years. (Until Bellatrix and her husband were incarcerated.) They have no pictures.
Staring at the mirror, just before the shock wears out and she tries to regain the liquid fluidity of her face once more, Tonks spreads her (thin, tapered) fingers against the cool surface and thinks Oh.