In A Delicate Deception, Cat Sebastian rounds off her Regency Imposters trilogy with an inversion of the classic "forgotten heir to a duchy" trope. A prickly standoffish heroine and two bi leads somehow manage to find their way to a happily ever after despite constantly getting in their own way.
Amelia Allenby, the illegitimate daughter of an Earl and his spellbinding mistress, has had enough. While her mother and sisters flourish in parties and salons, the noise, the crush, and, most of all, the layers upon layers of pretense demanded of society ladies proved far too much for her to bear. After walking out of a ball at the height of the season, midway through a dance no less, and without a word to anyone, Amelia has retreated to the countryside to have her embarrassing nervous breakdown in private. Accompanied by a large dog and her governess turned best friend, Georgiana, she hopes to stay there forever, writing smutty historical novels and being thoroughly left alone.
Sydney Goddard, a Quaker abolitionist and land surveyor, has found himself the heir to a burned-out stately home and all of the surrounding property after losing his brother and his brother's heiress wife to the fire. While he'd rather be anywhere else but there, it's also where his brother-in-law and former lover, the Duke of Hereford, is coming to meet him, and so he waits, taking long walks in the countryside and trying to work out if anything of the house can be saved. It's on one of those walks that he runs into Amelia, and what starts as an argument about property rights becomes a thoroughly rejuvenating relationship for the exhausted, dispirited pair.
Unfortunately, however, Sydney hasn't exactly been honest with Amelia about who he is. Not only is he the reluctant owner of the manor, but he's also her landlord, something she feels ought to have come up in conversation sometime before the first layers of clothing were removed. On Sidney's part, the revelation that Amelia is a society lady and one half of the mystery historian the Duke has had a somewhat spirited correspondence with has him feeling like he never knew her at all. Fortunately for them, neither Georgiana nor the Duke are inclined to let the two of them wallow in pride and misunderstanding, and with only a little prompting, they're more than willing to put in the work to mend the rest of the rift themselves.
As always with a Cat Sebastian novel, the story ends not just with a successful romance achieved between the main couple but with the creation, and reaffirmation, of a family network between the cast — combining both the found and more traditional varieties into a whole. In addition to Sydney and Amelia's romance, there's the building of a platonic life partnership between the asexual Georgiana and Lex, the Duke of Hereford, a firm Kinsey 6. Though they have no sexual or romantic interest in each other, they're both in search of stability, companionship, and a partner to raise children with — and their best-friend-courtship consisting of strawberries and arguing about historical conspiracy theories provides a delightful backdrop to the more tumultuous romance central to the novel. The pragmatic manner the two of them approach forming their partnership with, as well as the genuine affection in it, is genuinely charming and stands as a good representation of both asexuality and alternative approaches to family life then and now.
The novel's representation of disability, and ableism, are also up to the usual high standards of the author. Due to the time period's attitudes towards mental health, the depiction of Amelia's social anxiety (she doesn't understand what's happening to her or why) feels visceral and authentic. Sydney's approach towards it, as well as the mistakes he makes, rings true for a well-meaning, empathic man who nonetheless has no idea what's going on in her head and is only guessing what she might need. Similarly, the failure to consider the practical ramification of Lex's blindness, another result of the fire, is the cause of the initial rift between Sydney and Lex at the start of the novel. Needing a third party to read and write his letters for him had Lex unwilling to risk the mention of anything personal in them, much less affectionate — which Sydney, failing to think about the reason why, took as a rejection.
Amelia and Sydney are very similar in how they experience their bisexuality. Neither seems to have a gender preference, and neither of them struggles with their attraction to people of the same gender, rather accepting it as an ordinary part of themselves. So much so that Sydney all but openly admits to his past relationship with Lex before realizing the dangers of doing so while he and Amelia are repairing their damaged relationship in the middle of the novel. Amelia deals with his admission by bluntly admitting that she had a relationship with a woman in the season before she left London, letting Sydney know that the two of them are the same in that very important way and restoring the power dynamic between them.
There's also a commentary on the treatment of illegitimate children, the usual Sebastian dissection of the British class system, and a general gleeful subversion of social norms by the characters. While they may not be able to single-handedly fix British society and the way it treats people, they're damn well going to find a way around it for everyone they can, and they're going to be happy while they do it. Which, as far as queer sentiment goes, is timeless.