Character in Realism
Realist writers are really into describing, analyzing, and dramatizing personality. They delve deep into their characters' psychologies and dig into their motivations, actions, and emotions. Realism was all about understanding life, society, and the world. Often, the first place these writers started was with the psychological reality of individual people.
It's good to remember that when Realism was emerging, psychology as a discipline was also emerging. Towards the end of the 19th century, Sigmund Freud—whom you may know as the dude who came up with the theory that we all want to sleep with our parents—was developing many of the central concepts in psychology, including theories about the unconscious, dream life, and repression.
Realist writers during this period—and even before Freud (one person said that everything Freud said was already in Dostoevsky's novels)—were already interested in psychology, and this is reflected in Realism's obsession with character.
Chew on This
Check out how Fyodor Dostoevsky presents his protagonist Raskolnikov, the tortured (anti-)hero of Crime and Punishment.