Mostly the term "vassal" can be considered loaded with a sub/dom power dynamic, like dragging around a gagged and bound leatherclad pervert on a leash while forcing him to drink from urinals while you piss in them, patting them on the head saying good dog.
While it fits into the Paradox game-esque grand strategy metagame with familiar terminology, we are dealing with groups of regular players who don't want to get stomped by some nerd stacked mega alliance, not malnourished 14th century shit European territories. So I simply prefer terms like friends or allies, instead of vassals. Its a great manipulative technique to get people to trust and respect you and feel like they are a serious, independent clan, while you treat their players like chocolate chip cookie slave labor as you strive for your pure gorilla clan's Lebensraum across Calradia.
