Unity?

The majority of humans exposed to FEV vats died, those who survived became Super Mutants, and some very few of those, maintained their raw intelligence. Whether the result of the traumatic process, or some form of brain-washing carried out by the Master and his servants, Super Mutants generally have no memories of their former lives as humans.

With such intelligent Super Mutants being rare, it made sense that the Master would equip them with his most elite weaponry and train them to his highest standards both in tactics and ideology... thus was borne the Nightkin. Forming a secret police for the Master's Unity (AKA the Church of the Apocalypse) these strong, agile, and intelligent Super Mutants were given Stealth-Boys and advanced armaments.

Today as previously discussed, most Nightkin are insane beserkers used as lethal surprise assault troops by various packs of Super Mutants. Rare groups of Nightkin who are clearly "sane" (or as sane as a Super Mutant ever is) have been observed conducting raids in the far north of the United States throughout the former states of Washington, Montana, North Dakota, and Minnesota.

Scribes within the Brotherhood of Steel have heard these accounts and generally dismissed them as "legends", but there are some who believe that the continued activity of organized bands of Nightkin would suggest that a remnant of the Master's Army may have taken root and formed a community in the treacherous north. These opinions are derided as fanciful, as there are no known sources of FEV or West-Tek labs in those regions of the United States and without such the Super Mutants cannot breed and expand their numbers.

Perhaps this is true... but perhaps, just perhaps... a new "Unity" lies out in the unexplored wastes of the north...