Rejected by the Fae Duke, Claimed by the Shadow King

In the fae realms a twenty-year war is settled by marriage, and Lyra Vale is the payment. At the ceremony the duke refuses her in front of both kingdoms and takes her cruel sister instead. To keep the treaty from collapsing Lyra invokes the Moon Trial, an old rite that lets her claim protection, and the protector she draws is Dorian, the Shadow King. His living shadows bow to her. The protective mark that appears on her skin turns out to be the lost sigil of a fae queen. Assassins come for her, there are blood trials, and her own family works against her. Lyra learns she is the hidden Shadowborn heir and the only one who can settle Dorian's cursed power. Their bond could hold both realms together, though the people who arranged the war want her gone.