What alot of people have seemed to have forgotten is that D.C. has it's own underground transport system. Who is to say that the Gov't didn't have a (secret) underground connection to the west coast useable to only the president and top officials in case of emergencies. This could explain how the lone wanderer from Fallout could have traveled (safely ) to Vegas or the area. It would allow us to move our characters between games. Maybe make it so you had to beat both games first then you could bring in or take your current character to the other game to just shoot everything up. you couldn't play the story obviously with the other game character but you could explore and do the non vital mission quests. This could be a DLC all on it's own, taking the subway system from one to the other, befriending or fighting underground tribes to make a connection. It even adds in a story about the mole rats. Maybe an underground (hive) burrow of where they first originated and or mutated. How a faction of the brotherhood split and moved on. So what do you think?