" My father,” he said abruptly. “Pa—Lord John, I mean. He knew—knows?” “Yes.” Thin ice again. I didn’t think he had any idea that Lord John had married Isobel principally for his sake—and Jamie’s—but didn’t want him going anywhere near the question of Lord John’s motives. "

― Diana Gabaldon , The Fiery Cross / A Breath of Snow and Ashes / An Echo in the Bone / Written in My Own Heart's Blood (Outlander #5-8)