The protagonist in the story is the priest .
Other characters in the book are: the halfcast, the lieutenant, Padre Jose, his servant, his daughter, the Fellows family at the banana station.
What is the significance about the relationship of the protagonist to the other characters in the book.
In order to give a clear significance of the relationship of the main character and the other characters, I think it's necessary to indicate a short summary and the main theme of the story.
In the state of Tabasco, Mexico, where religion has been outlawed, all priests have been prosecuted or executed, except the "whiskey-priest". He is the only well-known Roman Catholic in the country left.
Several times he has been able to escape out of the country, but somehow every time he is stopped by something in himself. He keeps travelling through the country for six years, doing his job, his mission: say Mass, baptize children and hear confessions in spite of all the enemies and treacheries among the population. Finally he is arrested and executed.
The main theme is about the struggle of the priest against his religion, his God and himself, being a coward, an alcoholic, a father and definitely not a saint. Constantly he has got feelings of guilt about his shortcomings and mistakes against his religion. The other secondary characters are developed in a few short scenes. To me they are all very recognizable and put down very sharply by the writer. Those characters often bring out the central conflict of the priest and the lieutenant through parallels and contrasts. Some characters are very outspoken pious believers such as the woman in prison, Luis" mother and his little sisters and several villagers. They despise the so-called sinners in the world like Padre Jose, the half-caste, James Calver, and the priest himself. It's clear that Greene sympathizes very much with the sinners. For instance with Padre Jose, fat, old, and desolate.