If you think about the animals in the boat as a microcosm of society, then you can see the various social roles that are played. The hyena represents the ruthless of society who play by the rule "the survival of the fittest". He takes what he wants while not being concerned with the consequences of his actions. His only concern is to eat. The zebra represents those who suffer in silence and are powerless to act. Those are quickly destroyed in the "survival of the fittest". He passively accepts his fate, even though he is literally being eaten alive from the inside out. Some people in this world also die from the inside out. They refuse to speak up for themselves, and so suffer the actions of others. The orangutan tries to intervene, representing those who recognize an injustice and make the attempt to step up for what is right. Often, though, justice is beaten down by sheer power. Richard Parker, after witnessing the defeat of the powerless, takes control and administers justice. He does not kill at will, or else neither Pi nor Richard Parker would have survived. His threatening power, though, is the impetus Pi needs to survive. Pi musters his inner strength to overcome obstacles and rise to the position of supreme power in the boat. As a good ruler, Pi provides for his subordinates and is concerned for the good of the whole, not just himself.