姜太公釣魚——願者上鉤

Etymology
Grand Duke Jiang often went angling at the Weishui River, but he would fish in a bizarre way. He hung a straight hook, with no bait, three feet above the water. Over and over again, he said to himself, "Fish, if you are desperate to live, come and gulp down the hook by yourself."

Idiom

 * 1)  like the fish rising to Grand Duke Jiang's hookless and baitless line; a willing victim letting himself be caught of his own will