Jack served in the Marines, where he saw action in Afghanistan and was involved in a helicopter crash that killed most of his squadron. After returning from duty, he took over and rebuilt Private, the agency founded by his father, Tom. Jack restored the first-class reputation Private lost after Tom's Incarceration and death, opening up offices all around the world.

Jack has a twin brother, Tommy, who takes after his father and with whom he has an intense rivalry. Tommy enjoys tormenting Jack and even has gone as far as to threaten to kill him.

With his cool demeanor and good looks, Jack is a ladies' man who has trouble settling down due to his inability to share his innermost thoughts and feelings with others.