David is a young man who has been crossdressing for years. It started out as more of a fetish than any deep-seated gender identity issue, but Darla - his feminine identity - has been growing and developing with every girly weekend of self-exploration. I loved that David and Darla are presented as separate identities, almost a split personality. I can identify with the idea of a feminine self into whom one can escape, another self who has her own ideas, needs, wants, and emotions.
Of course, as the years pass, the roles begin to swap, with Darla becoming the dominant personality, driving David to some crucial life decisions, aided by one special friend. Just an overall lovely story, one that's more about identity than any sort of sexual longing.