I have a very generic and under developed idea for a faction of “raiders” that pretty much operate as the Regulators of Adytum do but on a larger scale. They would essentially be a protection racket, offering their “protection services” in exchange for a free license to take pretty much whatever they want from the town and to be able to order around the townspeople as they see fit. Living under their rule would be like living under military occupation, with all the suffering and exploitation that generally comes with that. As harsh as their rule is, some towns may see them as a lesser evil compared to your typical raider gang that will rob you blind and probably kill you. Of course, if a town refuses protection, then they might soon find themselves under attack by some suspiciously familiar looking raiders...
Lower ranking members and recruits would probably be like your average sadistic asshole that most post apocalyptic gangs seem to be made up of, but the higher ranking members and leaders might see themselves as providing a valuable service to the weak and infirm in the most pragmatic way possible.
Having thought more about this, the group would essentially be a cross between the Regulators and the mercenaries harassing Vault City. Not very original, I know.