So the Crusade for Arabia was won. By me. I got the entire de-jure duchy of Oman (it's a nice slab of land, but disconnected by sea and desert), and two connected provinces in the middle of the freaking desert, surrounded by Seljuk Mesopotamia on one side and the heart of the Fatimids on the other. Wew.
So then what? Something interesting. A Fatimid Prince decided to adventure for Anatolia (another Crusader Kingdom held by me). He loses. I imprison him. And while doing other things, I notice I have the opportunity to demand his religious conversion, which releases him. Curious (I could have sworn earlier he was zealous), I do so. He converts, drags his wife over to my court and converts her, and settles there. He has a claim on Anatolia... and the Fatimids (who are the rulers of Arabia, Cairo, sections of Egypt, and more than half of Nubia). An idea hatches. I land him (in, of course, one of my two provinces sitting in the middle of the Arabian desert), then I make a war for his claim, calling in Castille to aid me. The Fatimids are in the middle of wars with the Byzantines, Absynnia, and a (relatively) small revolt, so this is promising.
(meanwhile I get the traderoutes event. It goes to the Minaids (who broke off in a decadence revolt way back), who rule all of Egypt except Cairo (which is the capital of the Fatimids, amusingly), and a strip of land at the bottom which is also Fatimid. Somehow I become friends with the Sultan of Egypt through this. While waging war for territory that includes Mecca and Medina. Oh well.)
It goes well. Too well. I win, and revoke the Fatimids from my Prince friend while he still is a powerful king with literally only one county to his name (since this isn't Ironman, I tested letting him keep it, but he creates the Kingdom of Nubia if I let him go, which prevents me from taking everything). Now about a third of the entire Islamic world is under my thumb. The Shia Caliph is based in south Nubia (they own quite a lot of land there, incidentally), and is now my Spymaster. The abundance of really big, powerful vassals in the Muslim section of my Empire means that all the major people who could pose serious threats are in the council.
Couple questions.
Number 1: wat do.
Number 2: I have Religious title revocation. I could revoke everything, although it would probably lead to a lot of revolts and potentially destabilize the realm. Do I want to? I'm not sure there are enough courtiers to own all of this, even. I could land every single member of my family, that's an idea. I'd like to remake Arabia in a Christian image, but I don't want piss off my vassals. I could also ask vassals to convert, but I'm not sure what the results of that would be).
Number 3: The Kingdom of Absynnia got nothing out of the deal. I'd like to let them become a powerful bastion of Miaphysitism in East Africa (ideally let them take Egypt, but at least all of de-jure Nubia), but, obviously, I own it. Or rather, I own people who own it, which is an important difference. I have the option to create the Kingdom of Nubia, so theoretically I could set them independent (ideally with a Christian ruler) and see how that works out.
Number 4: The Shia Caliph soon called a Jihad, which spooked me, until I realized it was for Jerusalem. Besides being hilarious (Surely they'd rather call a Jihad agains the Infidel holding Mecca? Can he not call a Jihad against his liege? Is it because he is in the Council?), what does that mean for me? It was a Shia Jihad: The Fatimids were one of the only Shiite powers (the Minaids in Egypt are the other). If one of my vassals win, do I gain the Kingdom of Jerusalem? That would be hilarious, I admit.
Number 5: ...what now? I wasn't expecting to win. It's stable, even, at least for now (no telling what succession is like).