Okay so, I'm playing as the hispanic tribes about 20 turns in. I've conquered most of south east ibellica, have a nice line of border forts with the pirates and the valentines, so I decide to attack tahar.
At the border I find myself open to hire a bunch of mercenaries, so me imagining an awesome raiding party of desert mercenaries, I hire the whole lot and send em north to occupy the Taharian army. Works beautifully, I ambush the buggers and whipe em' out. So, my mercenary captain gets a promotion, and I'm all happy 'cus that means I can hire more mercs.
Next turn he's married to some Romulan skank. Then the very turn after that, he's blue, so me wondering why he suddenly changed to the scippii, I highlight him and realize he's the new heir to the empire. All I could say was huh, the romulans are going to follow some dirty desert mercenary captain, what a stroke of luck for the bloke.
(BTW if you were interested my army ended up getting crushed during a siege, so I need to rethink my strategy)