To Bubonicus, life is a disease and death is the cure. Armed with a pulse wand that is capable of analyzing and infecting any living creature with bacterial infections capable of conforming to a unique host and heavy armor, Bubonicus travels the galaxy killing all life he finds.
During their dealings with Ripjak the Guardians of the Galaxy learn that Bubonicus was behind the extermination of the martians that had conquered Earth, when he unleashed a plague on them.