Alvarro was an officer in the Golden Legion and captain of the Legion's cavalry. He was known for his brutality and lack of courage.
Prior to the Legion's battle with the pirate Akbet-Khrul a young officer named Halloran was promoted to lead the cavalry which angered Alvarro. Because of his bravery against the pirates, Cordell made Halloran commander of the cavalry on the Maztican expedition.
When Halloran was accused of cowardice after the natives captured and sacrificed the Bishop Domincus' daughter, the bishop convinced Alvarro to sneak onto the prison ship where Halloran was held and assassinate him. Hal was able to overpower Alvarro and escape from the ship but decided not to kill Alvarro. Later, at the battle of Ulatos, Alvarro was made captain of the cavalry and he led a charge that turned the tide of the battle. However, Alvarro was overcome with bloodlust and he led his men into the throngs of Payit civilians who had come out to watch the battle. While he was slaughtering unarmed natives he saw a beautiful Maztican maiden named Erixitl. He attempted to run her down but was foiled by Halloran who arrived near the end of the battle.
At the battle of Palul, Alvarro's men slaughtered hundreds of native warriors and peasants in the town square. After the battle Alvarro was chasing down natives in the fields outside Palul along with a lieutenant and he saw Erixitl. He attempted to capture her but was stopped once again by Halloran. Hal suffered a grievous wound during the fight.
Some days later, Erixitl was captured by the Legion in Nexal while attempting to rescue the Nexalan ruler from the hands of Cordell. Darien wanted Erixitl dead so she made a deal with Alvarro that she would give him a few hours alone with Erix so he could have his way with her if he would kill Erix when he was finished. Alvarro died when Erixitl tricked him by poisoning an alcoholic beverage she gave him.
Alvarro had red hair and a red beard.