Brave New World
How do John’s memories of his childhood change after the twins arrive? Why does he become angry with his mother? What happens to her as a result?
...
...
When Linda returns to a state of semi-consciousness, she asks for Pope. Until this point, John had been remembering the positive memories with her at the Indian village Malpais. Her mention of Pope, though, converts his memories to bad ones. Out of frustration, he shakes her in an effort to get her to recognize him.
Linda suddenly notices John's presence, but before she can speak, she begins choking and soon stops breathing. John realizes that he shook her too hard, and he runs to get the head nurse. When she arrives, they see that Linda has already passed away in her bed.
http://www.gradesaver.com/brave-new-world/study-guide/summary-chapters-13-15