Essence: 1) a perfume, a scent. 2) The basic, real and invariable nature of a thing or of its significant individual features.
As James noses down the gap between her ribs, he marvels at the smell of Lily Evans, the smell that is still so delicious, even after five years. It can be found all over her body, but is most noticeable in the places that belong to James alone.
In the hot niches of her neck, and in the hairless space behind her ears, and between her freckled breasts, and under the small shadow of her bellybutton, and all over her smooth back and behind her knees, and sweet and deep between her white thighs.
The smell is a light evanescent sweetness, that James finds on his hands all day after making love to Lily, in his cramped office he absently rubs his nose and a tiny trail of her scent drifts into his mind to be nudged into a daydream.