These are neutral factions you cannot join.
“The Outsiders are a hostile faction. These folks are always carrying high-tech gear, driving...Outsiders
“The Shiva's Favored are a hostile faction of mutants that live in most parts of the game world...Shiva's Favored
“Franklin's Riders are one of the few neutral factions and make their home in The Repository...Franklin's Riders
“The Bankers are one of the few neutral factions. Their primary purpose, as far as we've seen, is...Bankers