How are the following characters related to each other and the main character: Marshall, Melanie, April, Elizabeth, and the professor. How are they...

The only characters in this list who are related by family are Marshall and Melanie, who are brother and sister. Let's think of April as the main character and consider how the other characters relate to her.

Melanie is April's best friend and neighbor.Both girls have active imaginations and enjoy pretending. They develop the Egypt game. In many ways they think alike; for instance, they both generally avoid hanging out with boys their age,...

The only characters in this list who are related by family are Marshall and Melanie, who are brother and sister. Let's think of April as the main character and consider how the other characters relate to her.

Melanie is April's best friend and neighbor. Both girls have active imaginations and enjoy pretending. They develop the Egypt game. In many ways they think alike; for instance, they both generally avoid hanging out with boys their age, but they think that Ken and Toby, of all the boys in their class, are the funniest and most interesting.

Elizabeth is a neighbor and friend to April. Elizabeth is two years younger, and although she doesn't have as many imaginative ideas as Melanie and April do, she enjoys the pretend ceremonies and roles they perform in the Egypt game. 

Marshall is a friend to April, even though he is only four years old, and he is her neighbor. Marshall enjoys the pretend world of the Egypt game. April babysits Marshall at one point in the story. Marshall becomes April's "hero" when he alerts the professor to call for help when April is being attacked. Marshall looks up to April and trusts her; he will only answer questions from the police when April is there and asks the questions.

The professor is a man who lives in the same neighborhood as April. He enjoys ancient cultures like she does; in fact, he was previously an anthropology professor. He takes a surreptitious interest in the children's imaginative play. He becomes April's rescuer by calling for help when she is under attack. He becomes a friend when he gives April and the others keys to his storage yard so they can continue their game.  

Although April doesn't know anyone when she first comes to live at the Casa Rosada, she soon has a circle of friends that includes a girl her age, a younger girl, a much younger boy, and an adult man. They all are linked together by their interest in ancient cultures and imaginative play.