Grant Titles to Non-local people

Question

Should I grant titles of my newly conquered lands to courtier from my religion and culture? Does it help spread my influence on them?

E.g: An Orthodox Russian Courtier gets granted lands on Islamic Kazan region.

Answer 1

It is very important for numerous reasons that your vassals have a good opinion of you, especially those who hold landed titles. There is a large opinion-penalty for people of different cultures and an even larger one for people of a different religion. For that reason you should generally avoid to give any titles to people not of your religion and culture.

When you give an Orthodox character a Muslim county, the first thing they will do will usually be to set their court chaplain to "Proletylize" that county and make it Orthodox (especially when they have the "Zealous" trait). When you want your whole realm to be of one religion (you do!), then that's one more reason to avoid giving titles to infidels and heretics.

The only advantage it might have to have vassals who are of the same religion/culture as their counties is that automatically generated characters in that county will usually be of the local culture. That means these characters will like their boss better which means the vassal has a lower chance of getting assassinated or having to deal with rebellions. But this is usually a very minor aspect.

There might also be very rare situations in which a certain religious mechanic gives a vassal an unique advantage from which you also benefit. For example, their religion might give a vassal a Casus Belli against a neighbor which you don't have and give them the opportunity to conquer land for you which you couldn't conquer yourself (doesn't work with holy wars, by the way. A vassal can't declare holy wars when their liege is of a different religion than they are). But that's something extremely circumstantial.