The chapters describing Cathy as a child & teenager repeatedly show her "seducing" older men. At least one of these is described as looking like assault.
Adam as a child emotionally and physically abused by both his brother and his father; later, he is emotionally abusive to Cal.
There is also a part where Cathy's parents whip her for running away.
The evil Cathy is coded as asexual, and asexuality is conflated with inhumanity and abnormality. Quote: "without [sexuality] one would not be a human. One would be a monster." “everyone, I guess, who is not abnormal has foregathered with little girls in some dim leafy place, in the bottom of a manger, under a willow, in a culvert under a road—or at least has dreamed of doing so”