Neither in the hands of the player, nor completely AI controlled, Catholic CEOs are now identifiable characters with traits and prejudices. If your humble priests keep their conks clean and work hard they can end up sitting in the 13-seat College of Cardinals - the pool from which new Popes are elected.
On the death of a sitting Pope, factions with Cardinals get to participate in a murky, diplomacy-spiced election. It's yet another fascinating tactical tool in an already bulging player toolbox.
As in Rome: Total War optional tasks are tossed in your direction from time to time. Instead of the senate, in Med II it's often His Holiness who does the tasking; fall out with him and the offers dry up. Luckily, missions also come courtesy of the poorly-explained Council of Nobles. This convenient body subtly encourages you to expand, build up your armed forces and blood them with monetary incentives.
Above: That's gotta hurt. Every knight truly appears to fight for his life
More subtle/credible spurs to action come in the shape of immutable historical events. At some point during your campaign, the news arrives that the Mongol hordes are on the move. Eastern factions that don't adopt a war footing on hearing this are signing their own death warrants. In blood. Or possibly just ink.
Gunpowder is sprinkled into the game in a similar way. At a certain point you get news of its invention and exciting new branches appear on the already dense settlement structure tree.