Found this via the potter_prophet due to the pairings and have to say I absolutely loved it! It was funny and poignant and hot and sweet and Percy's fantasies were WONDERFUL as were the little personal asides. This bit particularly cracked me up
He licks at her clitoris, and her body arches, eyes fluttering shut, head leaning back, and he licks his way down to her...
(To her what? 'Vagina' sounds far too clinical. but 'cunt' doesn't bear thinking about, and the same goes for all those metaphors in Mum's books – 'the delicate flower of her sex, little more than a bud, but blossoming under the glorious attentions of his rough, hot, wet tongue; blossoming along with her need for his velvety manhood' springs to mind)