Jack would claim, after joining the FBI, that he did so because of the conditions he saw growing up. The gangs and drugs, he would say, have to be stopped. This isn't really true, however. He joined the FBI for the same reason he played football: the rush of adrenaline. It was also the same reason he flirted with gangs before his mother intervened and forced him onto the straight and narrow, insisting he focus on school and, when it became clear it could get him into college, his sports. His grades stayed good, but not exceptional, and his decision to major in law enforcement, with a minor in accounting, was to rest his mother's fears that he might not turn out good.
Not an outstanding agent, he was nonetheless one willing to sign on to the riskier ventures. Drug busts and anti-gang task forces drew him with their high potential for action and violence and his superiors grew somewhat concerned about the attraction. Everything in his life changed, though, when a simple drug bust turned into a bloodbath when three gang members bared their fangs and rushed the team. He was the only one to make it out and only barely. After writing his report, trying to play down the supernatural elements of what he'd seen, he settled into the realization that it was the most alive he'd ever felt. When SAD sat him down to go over what he'd seen and explain it to him, the information didn't hit him as much as the chance to persue these creatures full time.
Over the next five years, he took part in the most dangerous SAD operations, taking down the group that had killed him team as well as others. The exhileration began to get to him, though, when infiltration by a ghoul led to an ambush and, for the second time, the death of the rest of his team. His escape this time was too close for his comfort and he came out of the affair with several severe injuries which he is still partially recovering from. Since then, he has grown paranoid about ghouls, leading to a number of transfer requests, the most recent of which has brought him to New Orleans. A file on Columbian drug lord Baptiste Garcia has just fallen into his lap and a partner has been sent to assist him on investigating the suspicious circumstances of the man's relocation (including his continued existence, as his doctor was able to show overwhelming evidence of his terminal cancer to SAD agents).
Despite his recent brush with death and the resulting medical problems, Jack is still hooked on the thrill of the hunt and is beginning to itch for the next big assignment. The Garcia case may be just what he needs and he is looking for any excuse to force a violent conflict as he pursues the investigation. His craving for danger is made him a tough person to be around. He has the constantly on-edge persona of an adrenaline junkie, which most of his co-workers (including his partner) have misinterpreted as an unhealthy devotion to his job.
Jack is wary of his new partner and his suspicions have led to a lot of tension between the two since she arrived. This only aggravates her concerns about his mental health and leads to even more conflicts as she tries to mitigate his impulsive need for danger. He gets along a bit better with the non-SAD members of the FBI office in New Orleans, though he keeps a close eye on them. So long as they don't take too great a concern in his affairs, though, he figures they can't be out to get him, so his paranoia hasn't been noticed much around the office.
He's still in contact with his mother and his two sisters and practically supports the former, to his increasing annoyance. He's almost to the point of forcing the issue of a nursing home, just so that he doesn't need to worry about her and can concentrate on his work.
As a squad supervisor, Jack oversees a handful of agents who are generally investigating leads of police or political corruption. His task of going over their work and monitoring their progress has allowed him to bring to the attention of SAD odd discrepencies and red flags of vampiric involvement. So far, he hasn't found anything solid to work with, but it may only be a matter of time before he begins to untangle the web of kindred influence in the city and trace it back to its sources.