Weir himself has discussed the varying characterisations in the Martian, Artemis and PHM. In an interview at [0], he says: Well, my previous two books, The Mar

Weir himself has discussed the varying characterisations in the Martian, Artemis and PHM. In an interview at [0], he says: Well, my previous two books, The Martian and Artemis (which are also available for sale!) feature characters whose personalities are based on aspects of my own real personality, Mark Watney [from The Martian] has a lot of my own personality traits and Jazz Bashara [from Artemis] who is a Saudi woman living on the moon, believe it or not, her personality is based on largely the way I was when I was her age. I wanted to grow as a writer this time, so I made Rylan Grace’s personality not [be] based on my own. I created a new character out of whole cloth, not just using aspects of my own persona. So one thing I decided is that he’s conflict-averse and likes to stay in a safe environment (or something he considers safe) and being a middle school teacher is a safe environment. He doesn’t get a lot of adversity from the students. They look up to him because they’re not teenagers yet. He’s also a goody-two-shoes, so it makes sense that he would work with children. In a separate interview (that I can't find now) Weir states that PHM was an attempt to write a character that evolves, unlike Watney, who in effect retains the same character (wise-cracking optimist) throughout the book. [0] https://www.scifinow.co.uk/books/space-man-an-interview-with-the-martian-author-andy-weir/ https://www.scifinow.co.uk/books/space-man-an-interview-with...