The book Brian's Song is actually the script that was used for producing the 1971 made-for-television movie starring Billie Dee Williams as Gale Sayers and James Caan as Brian Piccolo.
Brian's Song tells the true story of the relationship of two football players from different backgrounds, with very different personalities, becoming close friends -- a friendship that would provide the basis for the film and book. Sayers, an introverted African-American from Kansas, and Piccolo, an extroverted Caucasian from Massachusetts, made the unlikeliest of friends, a bond that was established when the Chicago Bears made the two rookies roommates during training camp. The rooming of an African-American and a Caucasian during a period when racial tensions across the nation were very high was an unprecedented decision, but the two men succeeded in transcending racial barriers.
In terms of skills on the football field, there was a vast difference between the two players. While Piccolo was good, Sayers is considered one of the greatest running backs to ever play in the National Football League. Piccolo was good enough, however, to make the team, and the friendship between the two would continue until Piccolo's death in 1970 from cancer.
The health situation of the two men is where much of the story takes place. Sayers suffered knee injuries during the 1968 and 1970 seasons which prematurely ended what had been a brilliant career. Piccolo's career ended prematurely in 1969 when he was diagnosed with the cancer that would take his life the following year.
As far as family is concerned, Piccolo had married his high school girlfriend, Joy Murrath, and they had three daughters. Sayers also married his high school girlfriend, Linda McNeil. That marriage ended in divorce, after which Sayers married Ardythe Elaine Bullard. This educator is unaware of whether Gale Sayers has any children.