How is The Life of Pi, by Yann Martel, effective in revealing the complexity of human relationships?

In The Life of Pi, by Yann Martel,
there are two specific instances that i think reveal the complexity of human
relationships.

First, while Pi is lost at sea, he and the
tiger meet up with another castaway. This man attempts to kill Pi, and the tiger,
Richard Parker, kills the castaway and eats him, instead. Even though the man tried to
kill Pi, he is saddened by the man’s death. In terms of human relationships, there are
several aspects of the complexities here: first, Pi feels badly for the man who tried to
kill him. Secondly, as both are lost at sea, would it not have made more sense that Pi
and the man work together, thereby improving their chances at survival. In each case,
what I would expect to happen is the opposite of what
happens.

The second incident occurs at the end of the
story. When representatives of the company owning the sunken Japanese ship called
Tsintsum come looking for an understanding as whey the ship sank, they do not believe
Pi’s story involving the tiger. So Pi makes up a story about being captured, and a man
who cannibalized his mother and a crippled sailor. He leaves the men as they struggle
with which story to believe. It would seem to me that the very fact that Pi survived the
ordeal at all would make the story fantastic but not impossible. Within the complexities
of human nature, we find that people do not react as we would expect: they are not
always trustworthy, and at times, they are too cynical or too hardwired for “normalcy”
that they cannot think outside of the box.