Sonja was five and her German was better than his, and soon Nora’s would be, too. They were becoming Berliners while he moved through the city like a ghost, solitary and largely silent.
-- Narration (chapter 2)

Importance: These lines have the effect of establishing and emphasizing Robert's feelings of isolation in Berlin. Although he has a wife and two daughters, he feels like Berlin is not truly a home to him. His isolation extends from, among other reasons, the fact that he does not speak very fluent German, and he was born and raised in England.

I know Sergei Vanyashin didn’t fucking kill himself, and I know that whoever killed him…is looking for me too.
-- Patrick (chapter 3)

Importance: Patrick makes this statement during his and Robert's first extend period of interpersonal socialization. These statements reflect a fundamental element of Patrick's character arc, namely his assertion that he is being targeted by Russian government agents...