John "Jack" Marston Jr. was born in 1895 to Abigail and John Marston. Like his father, Jack was born to a mother who was a former prostitute. Jack is never called John in-game, but he was christened John Jr., but receives the nickname of Jack. Not much information is given about Jack's birthday, or birthplace.
However, Jack was around Dutch van der Linde's gang, along with Abigail
for the early years of his life. After John was betrayed by his former allies, Abigail and John dropped out of the gang, taking Jack with them. The two purchased a plot of land near Tall Trees and the Great Plains, which are located near the city of Blackwater. During this time, the family taught Jack different skills, such as how to read, and how to break a horse.
In the year 1911, John was approached by Edgar Ross, a governmental official whose position of power is never explicitly revealed. Ross had Abigail and Jack taken away, and forces John to wipe out his old gang, built up of Javier Escuella, Bill Williamson, and Dutch van der Linde. After John completes the task laid out by Edgar Ross, the family are allowed to return to their farm.
Once the family return to the farm, Jack and John begin to spend more time together. John teaches Jack to herd cattle, and how to hunt as well, using both elk and wolves as targets. Jack aspires to be like his father, and is afraid that John will disappear again. He feels that he needs to impress his father to stop him from disappearing again, and in order to do this, he risks his life by attempting to hunt a grizzly in the mountains. John discovers Jack badly injured on the mountain and apologetic for his actions. Initially he treats his father with hostility, as the two were not extremely close in the past.
End Game (Spoilers)
When the US Army attacks the Marston Farm, he tries to fight back against them with his father. However, when his father realizes they are outnumbered John makes Jack and Abigail get on a horse and escape. Eventually John is gunned down by the US Army along with Edgar Ross. When Abigail and Jack go back to the ranch after hearing the final gunshots, they see his body and bury him on a hill overlooking the ranch. The game then picks up three years later after Jack has become older and Abigail has also died. He takes up his father's honor, safehouses, weapons, fame and cash. He tracks down Edgar Ross while he is on a hunting trip in Mexico. When he confronts Ross, he remains unrepentant about murdering his father and tells Jack to go away before he gets hurt. Eventually the two engage in a duel with Jack becoming triumphant. Jack then goes on to make a name for himself in the West and build upon the reputation of his family.
Jack is bitten by Abigail Marston only seconds after she was infected due to Uncle
biting her. Through the rest of the game he is kept locked up in the master bedroom on the floor until the end when the plague is finally cured.
During the epilogue it is revealed that all of the Marstons died only a few months later - most likely from the assault Edgar Ross still stubbornly went through with.
During the final missions of the game, it is discovered that Jack enjoys reading books. Jack's preferred books are fiction, and are set in the Wild West. John jokes with him about writing books in later life, and Jack responds that he will write a book on his father, called 'The Day John Marston Stopped Shooting'. His aspiration is to become an author in the future, though he expresses an interest in joining the government as well. On top of this, he says he would not mind being an industrialist.
- Jack is voiced by Josh Blaylock.
- Jack once had a sister, but she died of unknown causes.
- Jack uses a Repeater Carbine as well as a Bolt Action Rifle during cutscenes.