Later on, he is seen taking care of the newly broken wild horses, moving them into the corral when Marston and Bonnie return to the ranch after breaking a few more. Before they got back, Amos told Drew MacFarlane about some horses he had seen outside Armadillo.
His first speaking appearance is in the mission "A Tempest Looms". The storm begins, while he gets the horses inside the barn for safety. Bonnie then arrives, and Amos tells her that the horses and the chickens are secure. Bonnie says that she is worried about the cowherd and they need to get them back, but Amos says that it is too dangerous and that the men will all die. Bonnie calls him a 'stupid man', saying that they will all die if they are left without a livelihood. Marston agrees with Bonnie and tells Amos to round up the men.
After the barn has caught on fire and Marston saves the horses within, Amos comes to see John and expresses his gratitude.
He is not seen again until John and his wife Abigail Marston deliver some corn to the ranch after MacFarlanes' whole supply was eaten by pests. He is only seen briefly, greeting Bonnie after the wagon has left. Three years later, in 1914, Amos can still be seen working on the ranch.
Amos is also an avid poker player, attending a poker game with his fellow ranch hands and other ranch residents and visitors after his ranching duties are complete. Marston can play alongside him if he so chooses. As with all poker players, getting caught cheating will cause Amos to challenge Marston to a duel.
His mother can be found buried in the Blackwater cemetery.
If the player shoots Amos in the face with most revolvers, strangely, he will survive. This is due to the fact that he somehow has slightly more health than most NPCs. This is the same for Bonnie after her only mission in Undead nightmare.
If caught cheating by Amos and challenged to a duel by him, if the player looks at the gun at his side, there will be no gun holster; his revolver will just be floating on his side. Killing him in the duel (as well as in free roam,) will make him disappear for quite some time in-game, but nevertheless, he will return. This is similar to how shopkeepers store are unavailable for 5 days if they are killed.
Sometimes, Amos can be heard saying, "Don't tell anyone I said this, but Ms. MacFarlane is sweet on that Marston fella."
During the cutscene Amos appears in at the end of "Exodus in America", no dialogue can be heard when he urges Bonnie to leave John, presuming that he is dead, and then again when he carries John to the wagon.