As the protagonist of Elex, he's a gifted soldier that, through the choices of the player, changes the history of Magalan.
Born among the Berserkers, Jax lived his childhood with his parents and brother Kallax on the Berserkers Island, a place included in the area of the Valley of the Damned, in which the Berserkers who broke the rules are exiled.
When he was very young, a commando of Albs raided the island, killing everyone in the process while he and Kallax were hiding under a barrow, witnessing powerless and scared.
Before they could be killed too, Wardek, an Albs soldier, took them with him, growing them as his own sons. Even though it seemed an act of benevolence, Wardek, who is sterile, indeed wanted to spawn a progeny that he could have shaped in formidable soldiers, helping him gain fame and honor and thus becoming an important member among the Albs.
Jex, with the years, the lack of emotions and free will, would have forgotten all of his past, living just to complete his missions and to serve the Hybrid.
Having superior endurance, skills, intelligence and combat ability of an average Alb, with time Jax climbed the ranks, becoming a commander and the next candidate for the position of Elexetor, the general officer of the Albs.
However, in his last mission in which he should have found "The Pilgrim" he is shot down with his aircraft, and failing his mission signed his death sentence as expected by The Directive of the Albs.