Insidious Two-Faced Lover

Su Chanzhen writes explicit fiction for a living and then finds herself inside the ancient world she has been describing, told that she can only get home by sleeping with a prince. She picks the Second Prince as the easiest target and starts working on him. The man she actually falls for is Song Jing, who moves through the court in the guise of the powerful eunuch known as the Nine Thousand Years and is not what that title suggests. She is carrying a cold poison in her body. Song Jing draws it out of her and into himself, and after that the two of them are tied together while the fight over the throne closes in around them, with the Second Prince and the court factions treating both of them as pieces to be used. What began as a task she wanted finished quickly turns into the reason she stops wanting to leave.