I think I came up with a fitting story for this guy. This predator was hunting, refused to kill his prey, and because of the steict honor code that says a predator who fails to kill his target must kill himself or someone else must do it, he ran off hiding and finds himself in a galaxy far away. He then begins to familiarize himself with the technology from this new galaxy and begins to hunt down and kill random targets until he catches the attention of a powerful sith imperial (Palpatine, Dooku, Vader, etc.) who hires him to be a personal assassin, and gives him new body armor with sith saber attachments and upgraded and retrofitted traditional predator weaponry. He then becomes one if the most renowned assassins in the galaxy and with his help, the sith will eventually conquer all of the galaxy, unless Luke Skywalker and/or a butt load of ewoks fight him and eventually win.