The Guardians are a group of First Gens that were hand picked by Apostle One to serve as a personal guard for their leader. Often picked because of their sheer devotion (though some are picked due to combat ability), they are modified further than they already are by Apostle One and placed near the center of the Sphere,where Patient Zero resides. They also often follow the Handmaidens, whom take care of Patient Zero and carry out small tasks for him around the Sphere (and occasionally outside on errands.)
They maintain their red paint scheme, but bear steel masks instead of the simple bone-like materials of their breatheren. They're usually known to be much sleaker looking than the other First-Gens.