Quote Originally Posted by JeromeGrasdyke
The key factors which determine whether a faction will accept a protectorate are:
* do you have territory which borders his (there must be at least one region-to-region border)
* superior overall faction vs faction military strength
* superior production capability (a combination of more settlements and a minimum amount of money)
* impending threat (enough force inside its provinces or in neighbouring provinces which you own)

Hopefully that clarifies matters a little..
Jerome, it clarifies matters a little indeed, but could you expand on this in more specific detail? What is the superiority level required, as since the BI version came out, I have been unsuccessful to negotiate one single protectorate...

Also it seems to me that the factors the AI looks at are a bit insufficient, the numer of battles won recently against the would-be protector as well as the number of territories lost to them should factor in as well.
A strange example is the Western Roman Empire demanding of me to become a protectorate every 4 turns or so without any actual means to enforce their will upon my faction (for example the Alemanni), they have fought about 20 or 30 battles versus me and have not won a single one. Gameplay- as well as strategy-wise it looks rather weird to have the cheek to demand protectorate status if you cannot seem to win against that faction's army.
Another example that illustrates the problems I see with this part of the diplomacy would be in the original campaign, when I played as Macedonia, I allied with Greece and got backstabbed 2 turns later, they took one city, in turn I re-took it and took all their mainland settlements. One turn later, a Greek diplomat appears and wants my faction to become a protectorate.
Surely a strange occurance?
The final critic I have about the protectorates and the negotiation thereof is the fact that often, when you elect to bow to their demands and become a protectorate, the protector will attack again after some turns without any provocation from my side. This surely must be an overlooked issue in the AI coding, as I can't see any logic behind a protector attacking its protectorate if it behaved peacefully.