Kim had an especially promising career in engineering and analytical operations when his life was apparently cut short along with 151 fellow crewmembers on the ill-fated Voyager. Kim, who was engaged at the time of his disappearance, had played clarinet in the Julliard Youth Symphony and was editor of the Starfleet Academy newspaper for one full year, where his series on the mounting Maquis problem fostered much campus debate. Though he enjoyed a stellar academic career and welcomed the challenges and adventures of exploration, Kim was a bit nervous about living up to his own expectations.

Fresh from Starfleet Academy, he became Janeway's Ops officer. Stranded in the Delta Quadrant. he feels his loss of home and family as a raw wound so early in his career. His genius nearly got Voyager home through a micro-wormhole if not for a time technicality, and he has transported halfway home with the Sikarians. He has been "devoured" by vengeful sentient energy beings trapped in his Beowulf holo-program, survived the "afterlife" of the Vhnori, and returned from the dead on the quantum level as well -- since he is actually now a twin from a duplicate Voyager that self-destructed. He also helped retrieve the Doctor from his damaged irradiated program and that he fought temptation to stay with the "'37s."

Like Janeway, Kim too is estranged from a fiancee, but he became instant friends with Paris and stuck with him despite his problems.