THE important thing in Crusader kings is piety - and it is often overlooked. prestige might be cool, it can help build an empire, but whether the empire does last is ultimately a question of piety.

Piety is linked to the notion of "badboy". When you are a nice person, your badboy is at zero. When you claim a title, you earn 1 badboy point. When you annex the aforementioned province, you earn 2 badboy points. When you diplo-vassalize a province, you earn 1 badboy point. An assassination attempt costs one, plus one additional if deiscovered.

Badboy is the reverse of good reputation. It harms in 2 ways. First, it brings more war against you. Second, & here lies the danger that destroyed many empires, it reduces you vassal's loyalty by 0,4/100 a month per badboy point. Therefore, if you claimed 4 provinces & annexed 3, your badboy is at 10, each vassal will lose 4/100 of loyalty each month, & will soon reach zero, then leave your overlordship - with a war, that is. Not cool at all.

The only way to reduce badboy, other than inheritance(whice reduce it by a mere third) is having piety. High piety. The accurate formula is unknown to me, but around 1000 piety, loyalty loss is reduced by 1/100 a month each year.

As piety is reset through inheritance, I therefore tend to manage my realm so : when young, crusading as much as possible to exceed 1000 piety, then use prestige available to expand in christian territory - always watching my reputation out. The most accurate way to know your badboy is to open the screen of one of your vassals, & hover the mouse pointer above its current loyalty. 1 badboy point = 0,4/100 loss of loyalty due to reputation. Keep it in mind every time you plan a nasty action.....