Who is "the boy" in the story, A Tiny Feast, and what is his importance?

The boy is a human child who was stolen from his mortal parents as a baby. These children, known as changelings in folklore, become part of the fairy world but are always returned to the human realm later in life. Usually, stolen children serve the fairies, but this boy becomes the surrogate son of Titania and Oberon. He is diagnosed with leukemia at the beginning of the story, and undergoes a course of harsh chemotherapy treatment to help fight it. The boy eventually dies, leaving his parents and the fairies to grieve him.