Amigos dos Amigos is a drug trafficking organization formed by current and ex-security forces and rebellious members of the Comando Vermelho who were ousted from the CV for organizing the murder of one of it's leaders in 1994.
The ADA it self was founded in 1998, and has since grown to become the dominant force in the Rocinha favela of Rio de Janeiro, which they ripped from the CV in 2004. An area that serves as it's primary power base these days.
They are said to still operate alongside members of Brazil's security forces, and are known for their semi-benevolent operations. Offering handouts and organizing festivals and parties for the residents of slums under their control.
They are fierce fighters however, and have been engaged in heavy fighting throughout Rocinha after an incident in 2011 which resulted in one of their top leaders being arrested. Permitting rivals to see weakness and begin to encroach upon their territory.