In Yann Martel's Life of Pi, a young boy rewrites his traumatic experiences in an attempt to cope with them and dissociate from them.
In Pi's alternate version of reality, he finds himself sharing a lifeboat with a hyena, a zebra, an orangutan, and a tiger named Richard Parker. After the hyena kills and eats the zebra and orangutan, the tiger kills and eats the hyena, leaving only Pi and the tiger in the lifeboat.
Pi uses rewards (food) and punishment (seasickness) to condition the tiger to obey him, and the two are able to coexist peacefully. Pi bonds with the tiger. He credits Richard Parker with helping him survive and protecting him from a French castaway who tried to kill him.
Approximately seven and a half months after the shipwreck, Pi's lifeboat washes up on a Mexican beach. After disembarking from the lifeboat, Richard Parker abruptly heads into the jungle without looking back. This devastates Pi, who feels a close bond with the tiger.
There are several possible reasons why Richard Parker does not look back. Perhaps Martel is calling attention to the differences between animals and humans. He is possibly suggesting that animals are incapable of feeling the same emotions as humans. This would explain why Pi chose to replace the humans in his alternate version of events with animals: he is distancing himself from the violence and barbarism he witnessed humans commit by pretending that these acts were committed by animals, from which violence and savagery are expected.
Another possible interpretation of Richard Parker's failure to look back at Pi is Pi's subconscious acknowledgement that he and the tiger are one and the same. Pi replaces himself with the tiger in his alternate version of reality. He is deeply disturbed by his violent capabilities and would rather believe that a tiger killed and ate another animal than accept that he killed and ate another person. Perhaps Richard Parker does not feel the need to say goodbye to Pi—because he is Pi. The two are one being and therefore cannot ever be truly separated.