The Martian
The Martian is an alter ego of the narrator. He is also the protagonist who comes to the Earth to discover the mystery of language.
Percy Walker
Percy Walker is both the protagonist and the narrator. As an observant person, he notices that a 20th century person is an unhappy one. That puzzles him: the question is why we feel so bad when the environment is good. He decides to conduct the research in order to find the answer.
Scientists
Scientists are represented as an elite of society. These people are interested only in the field of their scientific activities.
20th century person
A representative 20th century person is the main object of interest of the author. This is a person who tries to regain the life balance in constantly changing surroundings.