The co-owner of the Hat Creek Cattle Company and an ex captain of the Texas Rangers and he considers him to be the brains of the heroes and good characters. When he's not at work, he talks and hangs out with women, drinks, and plays cards. He's known in the territory for his incredible voice, amazing eyesight, and very good with his gun, an old Colt Dragoon. His hair turned white in his late 20s.
He's also twice a widower and part 1's plot starts off when Spoon, fallen hero and ex Texas Ranger, talks to and hangs out with the heroes after more than 10 years becoming a fugitive in the process. This inspires Spoon and heroes to take a herd of cattle to Montana and Spoon's telling of the state and Gus looking for excitement as well. They prepare by stealing 2, 500 horses and cattle from the Rio Grande in Mexico and making friends with lost irish immigrants and pretty much all the men citizens of the town.
The heroes survive a storm and later bury an irishman, who got attacked by water moccasins. They go to San Antonio to get a new cook while Spoon leaves them and goes to Austin. During their adventure, they battle Blue Duck, villain and criminal, and his gang, meet Johnson, rescue Lorena Wood, heroine and prostitute, and catch and hang outlaws, Spoon being one of the criminals. They later go to Ogallala and chill and have fun in the town.
Gus talks and hangs out with Clara Allen, heroine and former lover of Gus's, and tells him she will not marry him and instead offers him nearby land to live on and if Lorena will stay with her and her fam. Gus says he'll come back. In Montana, Gus hunts buffalo but is chased by indians and is wounded in his right leg. A doctor amputates Gus's right leg an discovers his left leg is septic and death will come to him soon and doesn't want doctor to remove it.
Gus says to Call to give his money to Wood, let Newt know Call is his dad, and Texas is his burial. Call burys Gus in Lonesome Dove.