Rakhalla

Siobhan Kearney grew up in the shadow of an alien embassy and the family that swallowed her mother. She is twenty-four when she meets the ambassador's heir: Rakhalla, black-carapaced, Earth-born, and the most dangerous being she has ever shared a room with. He is also her stepbrother. The succession requires him to be bound to a vetted human consort. He needs her. She wants nothing. So they make a deal — one year, one binding, one exit clause they both plan to use. His rivals poison her at a state dinner. He kills four men and does not let go of her afterward. The exit clause is still in the contract. Neither of them has ever mentioned it again.