Within a year of working for Biograph, Harron was noticed by newly hired director D.W. Griffith. Harron quickly became a favorite of Griffith and Griffith began to give the 14-year-old increasingly larger film roles. His first film for Griffith was the 1909 short crime drama "The Lonely Villa". The teenaged Harron was often cast by Griffith in the role of the "sensitive" and "naïve" boy, who was overwhelmingly sympathetic and appealing to American film-goers in the very early years of American motion pictures and not far removed from Harron's real-life persona; Harron was often described as a quiet and soft-spoken youth. It was these traits that helped garner much public interest in the young actor, especially amongst young female fans. In 1912 alone, Robert Harron appeared in nearly forty films at Biograph.