The titular dog is the protagonist of the story. He begins his life being separated from family and the freedom of farm life and is given away to Miss Barrett in London. He grows very close to her, and the two form the beginnings of a family, but his place is challenged when she marries Robert Browning and Flush is kidnapped. When he is returned to his home, Flush is able to grow close to Mr. Browning, and the three form a full family. Flush grows accustomed to his wealthy Victorian lifestyle, and he is proud of his social standing. When the family moves to Italy, Flush sees himself as a prince among the stray dogs.
Miss Elizabeth Barrett
The young Miss Barrett is in ill health when she lives near London, and she takes in Flush as a way to get herself out of the house and begin her recuperation. She grows extremely fond of Flush and is very loyal to him, and in spite of everyone’s counsel not to give in to the kidnappers, she agrees to pay the ransom so she can ensure Flush’s safe and healthy return.
Mr. Robert Browning
Elizabeth’s eventual husband, Robert, does not initially get along with Flush, who attempts to bite him frequently and feels he is being replaced by the man. Robert’s arrival causes Flush to grow distant from Elizabeth for a time, until Mr. Browning helps with arranging his ransom.
The dognappers who take Flush are simply very impoverished people who need to make ends meet. These characters are minor, but they provide valuable insight into the economic and class struggles at this time in England.