Continued with a historically started game in which I have thus far worked my way up from a random Muslim count to Sultan of Persia and things have gotten out of control.
I just lost an entire generation of rulers (thank Allah 1 of the children had a grandson) to my Voice of Satan son. First my ruler died of old age, despite not being 50 yet and having a family focus. Kind of wierd, but not impossible. Said ruler had 5 sons, 2 landed (better of the 2 has titles and so inherits first, the demon child, and 2 not very good options). I start ruling as my best heir and consider killing the demon child, but my plot power's too low and I'd get 40 tyranny for imprisoning him, so I just ignore him and go about my business.
Things go well for ~4 years, then my character gets an event. He's feeling a little woozy... Oh he's dead.
Enter son #2. Again, 40 for imprisonment and I'm currently trying to fix my dynasty's decadence, so that gets my attention as I pray I get a chance to kill that child. I have a son already, so I hand him a couple of titles in case I need to use him. Less than a year after taking power, this character starts feeling woozy. And now he's incapable and infirm. Well, probably won't live much longer, so I might as well drive up my tyranny. The little demon's finally put away and left in a cell to rot, then said threat grows up. 29 Intrigue skill. Off with his head and my character is revenged before promptly passing away.
Well time for the grandson. A Bedouin Sunni (like his liege the caliph) with sub-par stats. I've been trying to convert back to Persian because that's who we are and I'd prefer the horse archer retinues. I pick a Persian with almost 20 in both martial and stewardship. When I finally come of age, I find my self with moderate stats and my preferred culture finally(my great-grandfather converted to get along with his liege, but now I have high enough tolerance to avoid mitigate the penalty) and it's time to keep expanding.
I'm currently a vassal of the Abbasid empire which has blobbed big time and just repelled a crusade and stole a duchy from the Byzantine empire. I've been hiding under the empire for protection from outside forces and infamy. Somehow, the Shia caliph is a vassal of the Sunni caliph. Also, Danmark took Sweden and Italy is a united kingdom.