* "Faction before blood." This is a key phrase in the world of Divergent, serving as a motto for the Abnegation faction and highlighting their prioritization of community over family. While not a traditional idiom, it acts as a common phrase with a specific meaning within their society.
* "The knife's always out." This phrase, spoken by Christina to Tris, is not a direct idiom but functions as a metaphor for the constant danger and suspicion within the society, particularly in the Dauntless faction.
* "The only way out is through." This is a common saying in the Dauntless faction, representing their belief in overcoming challenges through physical and mental fortitude. Though not a direct idiom, it functions as a guiding principle and motivational phrase within the faction.
It's worth noting that while "Divergent" uses these phrases with a specific meaning within the book, they are not necessarily common idioms in the real world. However, they function similarly to idioms in that they convey a deeper meaning beyond their literal translation.