How I have to name the fraction?

[BarboII]

How I have to name the faction?

[The Sundance Kid]

What? This question makes no sense. Do you mean a 'faction'?

[BarboII]

yes, faction.

[Alexios Komnenos]

There's a document called Expand.text in the "text" folder inside "data" folder in which you can change many things, such as the names of the factions, the titles for the king and the heir (for example, if you want the leader of Venice to be called "Dux" instead of "Doge" you just must change the "Doge" that's outside the brackets:

"{Doge}Doge" to "{Doge}Dux"

or "{Poland}Kingdom of Poland" to "{Poland}Glorious and Most Magnificent Sovereing Kingdom of Great and Proud Poland"