The Duchess, Her Maid, The Groom and Their Lover is my first published novel, and though there are no paranormal elements, it's set in a fantasy world. More accurately, it's a land of Fantasy, of sexual fantasy. I thought the story would be best served by creating an alternate world, just enough different from our own world to free the reader's imagination but enough the same so that she doesn't have trouble navigating the story. Also, it was just plain fun to integrate real historical details with ones I made up completely, or borrowed from different time periods. It was even more fun to worldbuild in ways that would deepen the story's meaning.
On the surface, the world of The Duchess looks a bit like eighteenth century Europe. I altered the clothing as I saw fit, and tied in elements of nineteenth century European clothing as well. The details of décor are hodgepodge--I used elements of Medieval and Renaissance and Beaux Arts and Art Nouveau and even some Art Deco styles. However, I chose those styles based on thematic elements of the story. For example, to emphasize that the duchess is trapped in her role and in her palace, I chose to have her avoid her reflection in a "full-length oval mirror, its wide frame like a tangle of golden brambles," which could symbolize a barrier. Later, in her audience chamber, "the walls were hung with tapestries in lush twining, leaflike patterns of blue and gold," again giving the impression of her being tangled, trapped. Finally, the motif appears more explicitly in the corridor approaching her private quarters: "gold sconces shaped as unearthly smooth disembodied feminine hands, braceleted in cruel red stones," a more direct presentation of restraint. These types of décor come from three different time periods, but they're all linked because they serve the same theme.
All the characters born in the duchy or nearby have French names; I kept that consistent to give the sense of a coherent society with a common language. The two eunuch characters and one other character, who's genetically related to one of them, have names that originated in Eastern Europe. Hopefully, that fact subtly informs the reader that those characters come from elsewhere, or from an ethnic minority within the duchy. Eventually, I layer in that the eunuchs come from families who were politically at odds with the Duke, which reinforces the difference in their names. When the characters reach the coastal protectorate, a land whose economy is based on worldwide trade by sea, suddenly the names and appearances of people become much more varied: "She saw more dark-skinned people than pale, some so dark they appeared almost like shadows in the bright sunlight, others of various skin shades from olive to brown, and a few paler than Camille, their skins freckled and tinged red by the sun. They wore an array of styles, from pants and boots to long, billowing robes with sandals to a group in billowing trousers and short collarless coats with high-heeled wooden sandals that rattled on the cobblestones. Some looked completely foreign except for their clothing and manners, and some groups were mixed beyond her determining their origin." Names include Skeat, Kamah, and Captain Leung. To show a character who lives in one duchy but came from another, I gave a brothel keeper a combination name: Karl Fouet ("Fouet" is French for "whip," implying that it's a pseudonym). In addition, Karl has a tattoo of an octopus. Later, octopuses are a major decorative element in the coastal protectorate, implying that he was born there or lived there at one time.
I built into the novel a sense of the romance genre's history, though of course with an erotic twist. I love Georgette Heyer's novels, so from her came the idea to have Sylvie, the maid, spend most of the novel disguised as a boy. While the duchess is in hiding, rumors abound, and I drew on my knowledge of romance novel plots to create those rumors: "The Duchess had gone mad from her barren state, fled the palace, and tried to amass an army of peasants to overthrow her husband and rip him to bits…the Duke had repudiated her and their marriage, declaring her insanity the same as death. He was now negotiating with a neighboring duke for his fourteen year old daughter, or for a princess of a tiny mountain kingdom who possessed an army of eunuchs and bare-chested women warriors, or planned to elevate a lowly concubine to be his consort. Or was it two concubines?"
Finally, I had quite a lot of fun creating variations on erotica tropes. The scene in which the duchess is pleasured by her two eunuch guards is original only in that the two men are physically castrated, and thus doubly subservient to her pleasure. A bondage scene is given a new implication when the subservient character points out that he doesn't need to play at being subservient, as that's his role in real life; the dominant character must recast her demands. Other scenes are given a different angle through point of view. For example, the duchess is disturbed by watching her eunuch consensually flog the brothel keeper, despite clear evidence that it's an enjoyable experience for both. In the scene between the duchess and her maid, Sylvie, the duchess is new to sex with a woman: "Something intangible was missing, like a scent or a vibration in the air. Or--not missing, but nearly so. Camille concentrated on the specific shape of Sylvie's mouth, on her taste, on her petal-soft skin. After a few minutes, she was able to settle into enjoyment of the subtler pleasures of a woman's kiss."