NPCs won't ever come with you on adventures -- this is a Zelda style adventure game in that you're alone. But, in terms of settlement influence, you will have some influence there. Precisely how much depends on how much we're able to push this in beta and beyond. It's going to start out pretty dimple in those aspects, and how rich and deep that sort of thing gets is largely dependent on player adoption -- well, and interest in that part of the game from players, too.