The Bone Palace

The Bone Palace is a Low Fantasy novel by Amanda Downum and was released in December 2010. It is the second in The Necromancer Chronicles, and is a sequel to The Drowning City; however, the plots are self-contained, and only the main character, the necromancer Isyllt Iskaldur, carries over from the previous novel. Her mentor and former lover, Kiril, was mentioned there, but is an on-page character here.

Tropes used in The Bone Palace include:

Alliteration: both major viewpoint characters, Isyllt Iskaldur and Savedra Severos.
Anguished Declaration of Love: Ashlin for Savedra
Arranged Marriage: Crown Prince Nikos and his foreign bride Ashlin. Their marriage is a fractious one, although they appear to respect each other and the problems can't be laid at the feet of either of them; it's simply that their personalities clash, they aren't really to each other's sexual tastes, and both were in relationships when the marriage was arranged; Nikos got to keep his mistress, Savedra, but Ashlin had to abandon her lover, possibly explaining her unhappiness and anger.
Assassin Outclassin': Savedra frequently personally dispatches assassins attempting to kill her, Nikos, or Ashlin. She's aided in this by good information on threats from her mother's spy network. The lack of a good Crown intelligence/counter-assassin chief, since King Mathiros dismissed Kiril as his spymaster and refused to pick Kiril's chosen successor, Isyllt, has left Savedra to pick up the pieces -- especially since the King, and much of his intelligence and military muscle, is off at war.
Badass Princess: Ashlin. The first sight of her we get is at sword practice, and first impressions don't lie. Almost Rebellious Princess -- she would rather, personally, have had the life of a mercenary soldier than that of the Crown Prince's wife -- but duty won out.
Easy Sex Change: Averted, despite the magic of the setting. Savedra has an adam's apple and only small breasts, and retains functional male genitalia; given that she's from an exceedingly rich family and has their full support, this suggests that magical transformation assistance only aids in mild cosmetic ways.
Feminist Fantasy: it doesn't hit you too hard over the head with it, but Selafai and elsewhere appear to be fairly egalitarian as to gender. We see many women in what would be considered male roles in our world, including a female police inspector and captain of the guard, and nobody acts like this is unusual. Crown Prince Nikos isn't a warrior, while his wife Ashlin is, and Savedra, while not a warrior, certainly knows how to fight and is an effective counter-assassin.
Hot Amazon: Ashlin, at least in Savedra's eyes; she finds Ashlin attractive despite not normally being interested in women, and a part of that appreciation is for Ashlin's warrior physique, which gets plenty of mention when we're seeing things from Savedra's point-of-view.
If It's You It's Okay: Savedra and Ashlin both admit that they aren't normally attracted to people of the same gender.
Law of Inverse Fertility: Nikos and Ashlin are supposed to have children, so of course it doesn't work out; but when she has sex with Savedra, pregnancy is inevitable exactly because they don't want to get caught.
Love Triangle: Both Nikos and Ashlin are in love with Savedra, who loves both of them. After the tears when things come to a head, it looks like a Tenchi Solution is the answer they all choose, with the wonderful possibility that this will help relations between Nikos and Ashlin as well.
The Mistress: Savedra, to Nikos, the Crown Prince of Selafai. Their relationship actually precedes his marriage, but as Savedra is a transsexual, marriage between them is not permitted; a lot of the point of a Royal marriage is heirs, after all. Despite her unhappiness at Nikos having to marry Ashlin, a foreign warrior princess, the two women become friends; there are more strains between Nikos and Ashlin than between Ashlin and Savedra.
Necromancer: Isyllt Iskaldur's profession.
Our Vampires Are Different: the vrykoloi are vampires who live in catacombs beneath the city sewers, by ancient treaty with the Crown. They have some similarities with the "Nosferatu" school of vampire appearance, being fairly ugly to human eyes; they're yellow-eyed, pale, deathly skinny, with fangs, bat-like ears (often pierced), and a face only somewhat human-like. They can move impossibly quickly when they choose to, making fighting them difficult; silver, however, is a weakness. They shun sunlight mainly because of sensitive eyesight, as well as wanting to avoid notice; their treaty requires them to be discreet. They drink blood, obtained through willing or paid donors or from preying on the poor and helpless. Isyllt classifies them as demons, but they are apparently all once human, somehow infected or converted; there are two ancient vampire elders (both female) named Aphra and Tenebris who rule their society.
Sexless Marriage: Nikos and Ashlin's marriage is close to this. They have separate bedrooms and Ashlin frequently keeps the door between them locked. They have had sex -- Ashlin has become pregnant but miscarried the child -- but it seems that she can only tolerate it by getting very drunk indeed.
There Is Only One Bed: Savedra and Ashlin share a bed in the small village inn in Valcov. Ashlin is used to sleeping with others, but Savedra is not, except for Nikos. This seems to be one of the things that leads up to Ashlin's confession of love for Savedra soon after.
Transsexualism: Savedra Severos, mistress to Nikos, the Crown Prince.