So with seduction focus there's inadvertently the best succession law ever. Never marry, just impregnate everyone, especially people with the right traits, and then legitimize whatever son is capable enough. Get like 40 children and choose one.
This sounds (a) a genius idea and (b) the perfect basis for a long-lasting imperial society!
Isn't that sorta how Imperial Rome worked? Sure, if there was a legit son, he was the heir, but otherwise, it was like 'hey, randomdude that's capable, you my totes legit son now, go rule when I die'.
Not sure if it's still in there, but there was a "Adopt a worthy heir" item in the Intrigue panel that would be available if you had no heir and your monarch was over 40 or so, where you could adopt a randomly generated child and legitimize them as an heir. Or maybe that was just an add-on in the Elder Kings mod, I can't remember.
I frequently run into the "wife dies when my king is 55" trap, especially if I'm playing with Ultimogeniture. I try to marry the best available wife that's 40+ so I don't crank out an infant heir right before I croak. Even with Primogeniture it can be a trap, because if you start cranking out additional children, they're potential claimants who could one day come back and wreak havoc on your primary heir.
So, on a different tangent -- I present to you the story of Tuk Khazbek, my current game's version of Rasputin.
Tuk and his brother Eskhakh were Tengri Avar refugees who fled to my court when Avaria was finally overrun and rechristened Pannonia (in my game, the Magyars got curbstomped early, so Hungary never appeared. The Avars held Avaria until well into the 11th century until finally being ousted by Orthodox Bohemians).
I welcomed them into my court with little notice, until he knocked up one of my cousins. After a while, I started noticing that minor courtiers were being murdered on Tuk's orders. Then my Spymaster exposed one of his plots, and he had them murdered. Then he murdered my sister. Then my wife. Then another spymaster. And yet, I had no option for righteous imprisonment and didn't want to take the tyranny hit for imprisoning him or banishing him (not to mention I could never get a very high chance to imprison)
So, I decided to murder him back. Because of the wake of bodies he had left, I found numerous willing allies and quickly had a plot power of 292%. Consider him worm fodder, right?
WRONG. After about 15 failed attempts, I abandoned all hope and just waited for him to die, which he eventualy did (of natural causes) at the age of 67. At some point late in his life, he converted from Tengri to Reformed Suomenusko.
I really need to find an event viewer utility so I can figure out just how many people he had killed. I figure there are all sorts of folk tales in my realm now about Tuk Khazbek, and that he's become a sort of boogeyman to frighten small children.