Kro was born to the race of Deviants, an evolutionary offshoot of humanity which is cursed with an unstable genetic code causing random characteristics to crop up every generation. Kro, was born with a number of traits that are both extremely rare among his kind and beneficial in nature. Chief among these mutations is Kro’s longevity. Whereas the lifespan of most Deviants is about 1,000 year, Kro has already lived three times that long. In that time, he has studied and practiced the arts of war among humankind and frequently returned to the Deviants to lead their armies. At some pointing his career, he even had a brief affair with an Eternal (Thena, daughter of Zuras), perhaps the only such liaison between the two divergent human races. Kro has carefully guarded the secret of his longevity by taking periodic sabbaticals from his kinsmen, for fear that he would be subjected to genetic experimentation by those who wished to possess this mutant trait themselves.