Umber was once a powerful hunter, but she had a fateful encounter with a maverick by the name of Alter-R. After losing the battle, the maverick infected Umber with the Sigma virus, instead of destroying her. Umber now causes chaos and destruction wherever she goes. Her encyclopedic knowledge of the Hunters and their tactics makes her a particularily dangerous maverick to hunt. Hunter Thistle was Umber's protege before she became a maverick.