In Life of Pi, Pi in the human story is represented by Richard Parker. What does Pi in the animal story represent?He could be the cook, minus the...

Pi, in the animal story, represents his more humane,
decent, polite, religious, polite and controlled self.  Richard Parker, in the animal
story, also represents Pi, just his more barbaric, animalistic self that does all of the
difficult things that enable him to survive.  Pi is thrust into a very difficult
situation, where he is forced to do things that are extremely uncomfortable for him, and
even abhorrent, in order to survive.  He is normally an educated, respectful, vegetarian
boy who would never hurt anyone or anything.  However, if that part of himself reigns,
he would die quickly on the ocean. So, he gives in to his more animalistic side in order
to survive.  He lets that side take over to kill, take control, be dominant, fight the
odds, and survive the tragedies.

Often, in stressful
situations, people have to do things they never would have imagined themselves doing. 
Pi does that here, and embodies all of those horrific acts in the animal of Richard
Parker, a fierce tiger in whose nature it is natural to fight and kill.  Pi separates
himself from the horrible things he does by putting them outside of his normal self.  So
Pi, in the animal story still represents himself, just the human, humane, decent part of
himself, the part that would never do horrible things or hurt others.  He has to
maintain that part on himself in order to remain sane, and to keep a semblance of his
old nature.  So both Pi and Richard Parker, in the animal story, represent Pi, just
different parts of his nature that, in order to survive, work together.  I hope that
those thoughts helped a bit; good luck!