Who are the main characters in Open City? How are they depicted?

Open City by Teju Cole is a novel about Julius, a Nigerian-American doctor living in New York City where he is a resident specializing in psychiatry. The novel follows Julius as he wanders through the city making only fleeting contacts with other people, at times simply observing them and at times interacting with them and eliciting their life stories. 

One of the few friends of Julius we encounter is Professor Saito, a gay, Japanese-American literature professor...

Open City by Teju Cole is a novel about Julius, a Nigerian-American doctor living in New York City where he is a resident specializing in psychiatry. The novel follows Julius as he wanders through the city making only fleeting contacts with other people, at times simply observing them and at times interacting with them and eliciting their life stories. 

One of the few friends of Julius we encounter is Professor Saito, a gay, Japanese-American literature professor now dying of cancer who is at peace with his own mortality. He talks about how he was interned in a prison camp in the United States during World War II and how he kept himself occupied by reflecting on poems that he had memorized. 

He also briefly encounters another friend who is an Earth Science professor. He also reminisces about a dinner with the Indian surgeon Dr. Gupta and remembers his own grandmother. We are also introduced to Julius's girlfriend Nadege, who has left him.

Julius meets a variety of migrants and travelers including Saidu, a refugee from a civil war in Liberia, the Belgian Dr. Maillotte, his Belgian landlord Mayken, his childhood friend Moji, and the student Farouq. In general, many of the minor characters show up for fairly short scenes and are often present primarily to stimulate reflections about migration, identity, and ethnicity.