[Eldest Sister] tried to persist in advising me to behave myself...
-- Protagonist (Narration) (chapter 1)

Importance: When Eldest Sister hears the rumor that the protagonist is in a consensual relationship with Milkman, Eldest Sister appears to believe the rumor immediately. She does not accept any of the protagonist's attempts to explain the truth, and she takes it upon herself to tell the protagonist how to live her life. This dynamic foreshadows the novel's overall examinations of social pressure, repression, and conformity.

...the list of names that weren’t allowed in our district...
-- Protagonist (Narration) (chapter 2)

Importance: Early in the novel, the narration digresses into a discussion of the tense political divisions related to the Troubles. Although the novel does not use express labels, the main characters are technically allied with the Catholic regions of Ireland, and the opposition is the Protestant region of Northern Ireland, which is backed by the English government. This allusion to lists of names indicates...