As far as showing a non-isolationist chapter of the BoS, I didn't think 4 didn't do a terrible job even though it all culiminates in such a terrible conclusion (Blowing up the Institute being antithetical to basically any of their goals). Highly radicalized, highly millitarized and mobile. The Brotherhood shouldn't have interest in governing. Protection they offer should be a means to an end (of acquiring technology and recruits). I think making them a faction in a traditional sense makes them pretty fundamentally boring.