Quote Originally Posted by Ludens
In BI both Eastern Roman Empire and Western Roman Empire have a shadow-faction, called Eastern Roman Rebels and Western Roman Rebels. Any rebelling generals or cities will join these factions, taking any units under their command with them. I read somewhere they may occasionally rebel back. Other factions don't have these shadow-factions, so their generals always stay loyal.
The Goths have them too. I think originally the Berbers and the Huns were supposed to have them too, but I think they got deleted ( there are traces of a Moors and White Huns faction, I think ).

On that loyalty thing, I was going for something different in my new Western Empire campaign, and I decided to let Gaul rebel. Within three turns, a massive Western Rebel Empire came up, which revolted back to me entirely in another 4 turns...