How does the author make the idea of “faction before blood” come into role through the book? (give text evidence)

Beatrice Prior must choose a faction. She hopes her test will tell her what faction she should be in. The decision will then be easy. Faction before blood is the saying which pretty much means one chooses their faction over family. When Beatrice ends up being "divergent" this conflict between faction and family plays out throughout the duration of the book.