She could be a doll, at first glance -- indeed, the fair cream purity of her skin almost looks like porcelain. But a second glance shows her to be human, and, in fact, closer observation shows her to be a pure organic. She is petite, slightly rounded with the remanant of baby fat, but perfectly formed: she is the exemplar of a six-year-old human girl. By some standards, at least. Heart-shaped face, rosy cheeks and rosebud lips drawn in a cupid's bow, enormous limpid china-blue eyes, and a mass of pure golden ringlets the color of sunlight.
She has a vast wardrobe, but almost all of the items are permutations on this: calf-length dress, ribbon-sashed, with the white edge of lacy petticoats just visible below the hem. Invariably she wears white stockings and neat patent leather shoes, and usually a hat (perhaps a straw sunbonnet with flowers, or a prim little felt cap) or a headband, or a ribbon in her hair.
She is constantly accompanied by a little brown fieldmouse with sparrow's wings, who she calls Whiskers.
There have been Ernestines for a very long time -- but they're not the same child. Ernestine appears, like all Garden Children, as a young child, and disappears before puberty. It's just that there's always a Child named Ernestine. They look the same, of course (although there are slight variations; some Ernestines have a charming spatter of freckles across the bridge of their noses, and some have honey-brown eyes instead of blue ones; some are chubbier than others, some more slender), but they aren't the same girl. That would defeat the point of the Garden Children. She does seem to know certain things that past Ernestines knew -- permitting a certain continuity of discussion, albeit at a very childlike level -- but she always phrases these quasi-memories as 'A friend told me,' or 'I heard.'
There's nothing that really distinguishes her from the others; indeed, Ernestine would seem to be the pattern of which the other Children are permutations. She's also the public face of the faction, appearing at important Top functions in her prettiest blue velvet dress.
Ernestine lives in a charming little thatch-roof house in the Garden, with lilacs growing next to the door and a climbing rose trailing up over the top.