- "So, Victor, Lance, who has been ripping us off? All of us, because now we are partners. A team, as it were. Four brothers."
- ―Armando trying to discover who stole his coke shipment
In 1984, Armando and his brother, Diego, are the two most powerful drug kingpins in Vice City, but are also well known for their philanthropist views. The brothers, who are of Bolivian descent, also control their own crime organisation.
In GTA Vice City Stories, Armando and Diego are first mentioned by Jerry Martinez in Brawn of the Dead, when he informs Victor Vance that the cocaine shipment that he and his brother Lance had stolen from Martinez actually belonged to the Mendez Brothers.
Because of this, Lance and Victor are summoned by the Mendez brothers to explain the disappearance of their cocaine. The Vance brothers pin the theft on Martinez, and provide fake evidence to prove this. Victor and Lance continue to work for the brothers, including taking over a local biker empire site and killing rival drug dealers. Eventually, the Vance brothers outlive their usefulness to Armando and Diego, who order the Vance brothers to surrender their businesses to the Mendezs and leave the city in exchange for their own safety. Victor refuses to do so, so the Mendez brothers attack the Vance brothers and leave them at a fuel depot in Viceport. A Mendez hitman accidentally starts a fire at the depot, but the Vance brothers manage to escape.
With their ties severed, some Mendez Cartel members unsuccessfully try to take over Victor's businesses. Victor, with the help of Ricardo Diaz, hacks a Domestobot owned by the brothers and uses it to destroy the contents of their safe. In retaliation, the Mendez Cartel kidnap Victor's girlfriend Louise. The Vance brothers chase some Cartel members through the city to the Mendez Mansion. Victor forces his way inside and finds that both Lance and Louise have been injured. Lance survives but Louise laters dies. Following this, Victor confronts and kills a flamethrower-wielding Armando. Victor would later kill Diego, wiping out the Mendez Cartel in the city.
Of the two brothers, Armando is the more "charismatic" of the two. According to Armando, both he and his brother are utilitarians, with Diego being a fan of Plato's work and Armando being a fan of Aristotle's work. Utilitarism is the theory that mankind should always look towards finding pleasure, which is highlighted by both brothers becoming drug dealers for personal gain.
Armando seems to be based on Scarface's Alejandro Sosa, as he bears a striking resemblance to him both in appearance and personality.
- Louise Cassidy-Williams - Kidnapped and killed to lure Lance and Vic to a trap.
- GTA Vice City Stories
- Blitzkrieg (Post-mission pager message)
- The Mugshot Longshot (Boss)
- Hostile Takeover (Boss)
- Taking the Fall (Post-mission pager message)
- Unfriendly Competition (Boss)
- High Wire (Boss)
- Farewell to Arms (Post-mission pager message)
- Burning Bridges (Boss/Betrayal)
- Domo Arigato Domestoboto
- Light My Pyre (Killed)
- Interestingly, in the mission "Light My Pyre " if the player is to use the flamethrower against Armando he will not take any form of damage, however this may be a simple glitch .
- In the beta version of Last Stand, Vic originally also had to kill Armando Mendez, not just Jerry Martinez and Diego Mendez.
- Hostile Takeover, High Wire, Domo Arigato Domestoboto and Light My Pyre are the only missions wherein he appears without his Brother Diego.
- In addition, Last Stand is the only mission wherein he does not appear alongside his Brother Diego due to his death on the mission Light My Pyre.
- Armando has more mission appearances than his Brother Diego.
- Diego Mendez - Armando's brother.