Jack Joyce's History
Jack Joyce is the younger brother of William Joyce and the childhood friend of Paul Serene. During the events of October 2016, Jack returned to his hometown in Riverport at the behest of his friend, Paul, on the notion that Paul needed help with a "life changing" project. When he learns that Paul and his brother had created a time machine, Jack helps Paul activate the machine and unknowingly creates a fracture in time. When time begins to break down, Jack becomes the enemy and target of Monarch Solutions, headed by a viably aged Paul Serene. When it appears his brother is killed by Paul, Jack attempts to avenge William before he is approached by Beth Wilder, a Monarch employee invested in preventing the End of Time caused by the fracture.
Early Life
Jack Joyce is the son of Anthony and Kathryn Joyce, and is the younger brother of William Joyce. In December of 1999, their parents were killed in a car accident, leaving William to raise Jack on his home (something he states was "ill" for). The brothers' relationship became strained afterward, with William once blaming Jack for their deaths, but the latter would become more and more independent from William.
Jack would meet and befriend Paul Serene, who would have a close bond with as they got older, being the proactive troublemaker of the two. When they were in their early teens, the two run upon a suicide, but decided to keep the incident a secret. Jack and Paul had a lengthy record of causing trouble, with Jack having been arrested numerous times for grand theft auto, assault, and theft attempts.
Becoming a Drifter
In 2010, Jack decided to leave Riverport, and started a nomadic life-style across the globe. Jack remained in contact with Paul via email, but loss touch with William, further straining their relationship. In Laos, Jack received weapons training, and presumably settled in Bangkok, Thailand for a couple of years. In 2015, he was arrested for weapon-related charges, but they were dropped for unknown reasons.
Quantum Break
In October 9, 2016, Jack Joyce arrives at Riverport University where he is reunited with his best friend, Paul Serene, and being introduced to the time machine. Just as they are about to begin testing, it malfunctions and exposing them to chronons, giving them time manipulation powers.
As Jack and his younger brother, William Joyce, escape Monarch Solutions' soldiers, they ended up being confronted by its leader: an aged Paul Serene, having used the time machine to escape the chaos only to fall to the End of Time. Serene then founded Monarch at 1999 to prepare for this event.
Jack opposes his former friend to prove him wrong that time can be changed to stop the End of Time. After stopping the end of time, he begins to suffer from Chronon syndrome and gains precognition like Serene.