My IRL friend and I are both playing Ireland in an online match (she's Munster, I'm Connacht). It is vicious. At first we allied together to unite Ireland, and I promised that she could be the King as long as she helped me revoke the unruly Breifne lord. Then she started getting greedy and taking things I was trying to claim, so we got into a war, which she eventually won. For 50 or 60 years, we remained at a tenuous peace, where I forced her into Elective Succession and gave one of my cousins Dublin (and, thus, the Duchy of Meath and an extra vote). She put Feudal Taxation at Harsh.
At around the 1130sh mark, where we started tonight's game, all hell broke loose. I assassinated her main character (First King of Ireland), who had killed my father AND grandfather in battles. Then she became my mother, as well as Queen of Ireland (I had voted for my mother, even though she was in her dynasty, because her original heir was me). Nobody much liked this woman, because she was actually a Breton (and I don't think she was even from Ireland). I ended up assassinating her with the help of the Earl of Ossory. Her aunt (First King's sister) left Powys (in Wales) to be the new Queen, after getting votes from Meath and Leinster (dope AI always gets greedy right when I'm about to be King!).
We fight a multitude of bloody Irish revolutions against the Tax Queen over the next fifteen years. The first one ends in an assassin war where my assassin fails and hers stabs my Main in the chest. He is replaced by his legitimized bastard half-brother. The half-brother proceeds to join the next revolt, and is imprisoned. His regent joins every revolt after that in an attempt to rescue his liege. The Queen is always alone in these wars, but has so much money in the treasury from the harsh tax that she just buys mercenaries. I turn the tide of the revolts by hiring smaller bands of cheap mercenaries, who tear Ireland apart. Eventually, after the 5th of 6th war, she runs out of money. However, she has just run out of real enemies from the AI, too.
Meath arranges for me to get out of prison, and I become the Chancellor (possibly in an attempt to placate me). After a few years, the Earl of Ossory and I murder the queen (who is trying to get some random from her Dynasty elected). She is replaced by the random, who the Duke of Ulster and I kill, thus making the Duchess of Leinster the Queen of Ireland (Ruler #5, with #4 lasting less than a year).
The very first thing the Duchess of Leinster has done is attack Gwynedd (which I approve of). Right now we're waiting for that war to be over, and then it's back to plotting to get the throne back.
It's such a sordid game. Between the two of us, our families are constantly interelated thanks to a huge flurry of marriages I made with her family and her branches when she first became ruler, along with the marriage of the sons of our first two Mains. Tonight alone, I assassinated four of her Mains (one of which was my Grandfather, the other of which was my actual Mother), I almost lost the direct line of succession (thankfully I legitimized that bastard!), and the future of Ireland is uncertain.
The rest of the world is pretty basic, except that the Iberian Peninsula is dominated by Muslims and England is constantly fractured and has been in a succession war for as long as I can remember.