This has to do with the entrenched "royals" of the old versus the upstarts. When the two scions live across the street, there is bound to be interaction. When the butler in one house goes to assist at the others, he is going to pay a price. I can't go into all the nuances. Watch the show. But the tensions building all along are really striking. Also, the Russells and their lust for power and esteem make really terrific villains.
Review of Heads Have Rolled for Less
