They run the double G, ensuring slick operation of their juicy business and personally handling prospective talent. Though they show respect for the made men of any of the families, they owe specific allegiance to the Mordinos.
If the Chosen One impresses the brothers in an audition, they have the potential to become a full fledged Porn Star.
Collect tribute from the Corsican Brothers: Big Jesus Mordino wants the Chosen One to intimidate the Corsican Brothers into paying their usual tribute. IMPORTANT: if completed the game and then accepted this quest, there will be absolutely no dialogue option to collect the money due to them cutting the Chosen off from the "Enclave adventures."
To get an audition with the brothers, the Chosen One must either be highly charismaric or have a good reputation in New Reno (via the Made Man or Prizefighter titles). To impress them enough to actually take part in the filming of a movie, the Chosen One must also have a high Endurance and Agility.
It should be noted that the name "Corsican Brothers" is a bit misleading, however, since there is only one of them. At any time, there is only one actual non-player character; the names are simply switched.
That there is only one of the "Brothers" is likely a reference to the 1941 movie The Corsican Brothers starring Douglas Fairbanks Jr. as both of the two Siamese twin Corsican brothers, separated at birth.