Cephalus, Polemarchus, and Thrasymachus

Hierarchy of characters: Each figure represents a component of human soul, and together form a microcosm of humanity. 
A. The first set of dialogues (set A characters prefigures the superior natures of set B characters.) 
Cephalus: Appetitive part of the soul, businessman, the venerable paterfamilias (father of the family) concerning with satisfying the needs of body and making money
Polemarchus: Spirited part of the soul, son of Cephalus, a solid patriot who defends the honor of his father, friends, and fellow citizens, 'Warlord', honor and loyalty
Thrasymachus: Rational part of the soul, a cynical intellectual who rivals Socrates as an educator of future statement
B. From Book II onward
Glaucon: appetitive, 'gleaming', the war-like brother
Adeimantus: spirited, hedonistic and the pleasure-seeking brother 
Socrates: rational, philosophically-minded
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The first mini-set of three dialogues:
1. Cephalus: Justice is piety to gods. The embodiment of the conventional opinion which Socrates chases out of the dialogue so that the audacious arguments could be pursued without the oversight of traditional authority.
2. Polemarchus: Justice is the loyalty, patriotic sentiment that the citizens of one polis feel for one another in opposition to other places. Justice is devotion to one's own. 
 Socrates challenges that loyalty in itself cannot be justice as we make mistakes in distinguishing friends and enemies (reference to Schmidt). And such unreflective grant of moral priority to one group than another is bound to result in injustice.
 Polemarchus insists that the survival of the state rests on a vivid sense of what it stands for and what it is not and who are the enemies. Sorcrates' disillusion of that framework challenges the possibility of political life by questioning the distinction between friends and enemies. 
3. Thrasymachus: Justice is the interest of the stronger, made by and for the ruling class vs the ruled. Human beings, and collective entities as well, are first and foremost dominated by the desire for power (reference to Hobbes). Every polity seeks its own advantage against others.
 Socrates challenges by saying that people in the power could make mistakes in recognizing what is really and truly in their interest, i.e. justice is not power alone, justice requires knowledge and reflection.
 But what kind of knowledge is required? Thrasymachus contends that justice consists of the art of convincing people to obey the rules that are in the interests in the rulers, the true ruler should have the courage to act unjustly for his interest. The best life is to do maximum injustice without being discovered.