Jim Martin is the current union president and was once a good friend of Carlos Fonnegra.
Jim Martin's family was among those that left Columbia during his childhood. Since then, he became good friends with Carlos Fonnegra and Alicia Fuentes, both of whom were children around his age and were with him when they all moved from Columbia.
Introduced as a running candidate for union president in "The Politics of Time", Jim called Carlos late one night to come to their house to pick up Alicia, who was apparently bothering him about dirt she picked up about his campaign.
The next day, Alicia turns up dead and strangled in her own apartment. Kiera becomes suspicious of Jim when he seems to be hiding something.
Eventually, it is revealed that Jim was having an affair with Alicia, and that she had been asking Jim's wife, Heather, to make Jim stop pestering Alicia. Jim denies this and insists that it was Alicia who couldn't move on from their relationship.
Carlos and Kiera briefly suspect Heather, but Kiera eventually realizes that the one who really ordered the hit was his campaign manager, Sara Davidson, who was secretly funding Jim's campaign with the help of some large contributors that Jim had apparently been stubbornly turning away. She had told Liber8 about Alicia knowing about them, but she apparently had no idea that they would kill her.
Jim apologizes to Carlos, who is still shocked about the recent revelations, but Carlos tells him that their friendship is over, particularly for all the lies he told for "politics".
In the end, it is revealed that one of the contributors Sara had accepted campaign funding from was in fact Edouard Kagame of Liber8, with whom Heather later introduces Jim to. Both Carlos and Kiera realize that Liber8 will use Jim's newly appointed powers of controlling port activity, and might even make him run for mayor someday.
As Kiera suspected, Jim was intending on running for mayor after his victory as the union president. Jim planned on succeeding again with the help of Liber8, now under of Sonya Valentine, who then proceeded to let Jasmine Garza assassinate the incumbent mayor. Liber8, of course, intended on using Jim when he gets in position.
Separating and creating his own faction of Liber8, Travis Verta wanted the soon-to-be elected mayor, Jim, "in his pocket", so he threatened Jim into working for him while keeping up his partnership with Sonya, as well.
Fed up with the conflict he was stuck with between the two, Jim tricked them into meeting each other. While Travis was expecting a meeting with Kiera, and Sonya hoping to see Julian. Most likely expecting to have them kill each other, Jim unwittingly helped the couple reconcile when they realize his deception.