Conveniently for me, I wrapped up the Desperate Duchesses series just in time for the new book in Eloisa's Fairy Tales series to appear.
The Duke is Mine. Tarquin, the Duke of Sconce, lives for logic, order, and mathmatical problems. His mother is famous for having written a treatise on how to be the perfect duchess. Note: Tarquin isn't married.
Olivia Lytton has been raised to be the perfect duchess. Well, her parents tried - Olivia is less inclined to be sweet, attentive, and proper and more inclined to tell bawdy jokes. The "duchification" system, as Olivia and her twin sister Georgiana have dubbed it, has served to gain Olivia a betrothal to the heir to the duchy of Canterwick. The only problem is that Rupert will never grow into his full faculties - he was deprived of oxygen at birth and while sweet and energetic he will always remain a child in many ways. When Rupert goes off to fight Napoleon (his father has arranged a "safe" commission), Olivia accompanies Georgiana to Sconce where there is a chance that Georgie could impress the Dowager Duchess with her absorption of the duchification guide.
Nothing goes according to plan. While Georgie can pull off a superficial "perfect duchess" she'd really rather attend a lecture at Oxford. Quin, master of logic that he is, is inexplicably drawn to Olivia's outspoken, goofy personality. Olivia would rather not marry Rupert but she feels she really doesn't have much choice - particularly since Olivia and Rupert had been sent to her parents' library to engage in some improper behavior (a truly nails-on-chalkboard scene but written for that purpose) in the hopes that Olivia might conceive a child (which she didn't, and couldn't the way the scene played out). When Rupert is injured, Quin and Olivia undertake a daring rescue to bring him home from France.
The Duke is Mine isn't quite as magical as A Kiss at Midnight but less "realistic" than When Beauty Tamed the Beast (read: the heroine doesn't almost die from scarlet fever and aspergillosis which she ought to have contracted after spending several days in a chicken coop). This is a much funnier book, too, with the "duchification" system, the Mirror, and Olivia's dirty jokes. The Princess and the Pea tie-ins are really well done, from the downpour on the night Olivia and Georgie arrive at Sconce and the "perfect duchess" competition to the "pea" that appears under a mattress near the end. It does make for a Regency fairy tale.