Barrett Johnson is U.S. Army Ranger, and a Champion in the Fourth Great Games of the Hydra.
Lieutenant Barrett Johnson of the United States Army Rangers had apparently built up a reputation as a great soldier, and because of this he was selected by the King of Sea, Garrett Caldwell, to be one of his four representing Champions during the Great Games of the Hydra.
It is unknown if Johnson was unaware of this decision or even of the existence of the Games, though given his high ranking for success in the Games, it is highly likely he did in fact know. Either way, a short time before the Games were set to commence, he was taken to the Underworld, along with a few of his friends/family who were to be his hostages, and had an explosive device implanted in his neck.
Johnson, like the other participants in the Games, awoke in a strange cell to find himself confronted by a strange man in a bull-shaped helmet. After killing his opponent, Johnson ventured out of the cell to find himself among thirteen others who had succeeded against their enemies. They were then all confronted by the man calling himself Hades, who explained that they were all participants in the Great Games of the Hydra.
After being thrust into the Second Challenge, Johnson managed to make it through the rising waters and escape the arena. However, the Champion who had claimed the Golden Sphere, Gregory Brigham, was offered a reward of his own choosing; he chose to have Johnson executed, since he was the next-highest ranked Champion to win the Games. Within seconds, Vacheron detonated the explosive in Johnson's neck, killing him instantly, and his hostages were also killed moments later.