The objectives of the player in Medieval Europe are many and may or may not coincide with the aims of leaders of same kingdom.
The control features in Medieval Europe are kept to a minimum because the philosophy of the game is to allow free player movement and decisions such as strategic maneuvers, betrayals, esponiage, corruption etc...
A player can fully endorse certain leaders to make (for example) the Kingdom of Naples the strongest kingdom in Europe and so rich and powerful to be able to put under siege all the other kingdoms and eventually conquer all of Europe.
Otherwise, the player views differ from those of his leaders, so he can concoct a plot to break the chain of power, by recruiting a private army. He can become a spy or a mercenary, and sell himself to the highest bidder, or work towards a political or ecclesiastical career.
The ultimate goals that can be pursued are various: acquisition of power, success, wealth, overthrowing power, build your own army, work on a strategy to safeguard and make your kingdom the most powerful.