I am not sure what the effects of the rebellious trait should be, but in my game, the muslim sheik of Lorraine, a vassal of the king of the Seljuks got that trait, but it didn't change anything.
The Seljuks have conquered almost all of the duchies of Upper-Lorraine, Switzerland and Savoye. After almost 60 years, none of the vassals that they have created there has yet broken away.
The Seljuks have conquered almost all of the duchies of Upper-Lorraine, Switzerland and Savoye. After almost 60 years, none of the vassals that they have created there has yet broken away.