All I want, Strike,” said Bristow hoarsely, the color high in his thin face, “is justice.
-- John Bristow (Part 1, Chapter 4 paragraph p. 32)

Importance: Here, John explains to satisfy Strike's curiosity about why John would want Lula's death investigated, that he wants justice to be done. The irony here is that John is the murderer, and is seeking justice against himself.

But they had already tried, again and again and again, and always, when the first crashing wave of mutual longing subsided, the ugly wreck of the past lay revealed again, its shadow lying darkly over everything they tried to rebuild.
-- Narrator (Part 2, Chapter 4 paragraph p. 76)

Importance: Here, the narrator reveals the tempestuous relationship that has existed between Charlotte and Strike for fifteen years. No matter how much they want to get back together, the past cannot be undone. It serves to haunt the present continually.

He had lost the army, and Charlotte and half a leg; he felt a need to become thoroughly...
-- Narrator (Part 3, Chapter 1 paragraph p. 166)