None of my adventurers have any connection, political or other to my nobles. I've played them largely where they spawned, and more or less loyal to his nation. They may travel within their allied lands, but I have at least one island where the noble and adventurer realms are at war. There's no suggestion or evidence they are working with each other, but I've seen that held against players before (with the adventurer paying the cost).
So you don't want them allied, or opposing your nobles, what's your alternative? Make the characters exclusive (advy or noble?) or get rid of them entirely? I'm not kidding when I say, at times, the adventurer character is the more fun to play.
