Understanding Personal Union Mechanics

[Pippin123]

I've been doing some testing (killing heirs and kings with the console) on the dynamics of EU4 royal dynasties, but it's still very arcane to me.

Here's what I found :

• If you have no RM and no "extended family" that share your dynasty in another country, a random noble from your country will take the throne (Tested with England: York, Lancaster, Holland, Plantagenet each took turns)
  
  
• If you have even one RM, a noble from the RM's dynasty will take the throne.
  In case of multiple RM, it seems it's the most powerful country that takes priority. Stuart (Scotland) took over the throne with -100 prestige vs Cleves +100 Prestige.
  
  
• In case you have no RM, but share dynastic lines, nobles from your Dynasty will keep spawning, and sometimes, it's the actual ruler of the country you share blood bonds with, resulting in a PU. e.g. Killing all De Valois in France results in a PU with Provence, despite no RM.
  
  
• when there's both RM and Blood bonds, I just don't understand what's going on anymore... ;)

Most PU are followed by a succession war, usually from a Rival/Ennemy of the country inheriting, apparently just out of spite (no previous RM or bond with the inherited country).

Anyone knows how the AI decides who gets on the throne ? It seems Prestige matters little, for dynastic change, but it's supposed to do for PU...
Is there no way to have a PU without a Succession war ? (I know I did in single player)

[Bitter]

PUs are incredibly rare, inheriting someone instead of just PUing them is even rarer (Inherited France in one Ulm game.)

[The Rainmaker]

basically personal unions do sometimes happen out of the blue and most of the time claim throne doesn't work.

the sole seeming purpose on claim throne is to do a succesion war with someone from your own dynasty. It seems useless outside of that.

basically unless its the same dynasty and you start the succession war dont try for personal unions because they will just randomly happen or not happen.

[Mikey]

If there is only 1 contender then a succession war will not happen, if there are multiple the two with the highest prestige will duke it out (the highest prestige gets the initial PU during the war unless you have "claim throne" on them)

[Pippin123]

But I was able, as HRE, to use Claim Throne on Hungary, who was not of my dynasty and there was no succession war. Maybe because the other countries didn't dare, given our relative size.

@Mikehsan I tested it, and it's not 100% correct. Provence (same dynasty, RM) entered a succession War for France with Savoy, despite Savoy having no RM with France, andno significant prestige advantage (but they were Provence Rivals)

[Ursinho Flinflon]

i do believe the game is a little "broken" on these details, a lot of shady or random results from the RM mechanics, paradox could really improve this stuff, or at least explain it to us
(i really like the system with CK2, they could use some things from this game for EUIV)

[Mikey]

Pippin, there is a Hungarian event that fires giving them a habsburg king, when he dies you automatically get a PU CB on them.

[Pippin123]

That 's not it. I was Trastamara not Hasburg (I created HRE starting as Castile, for the achievement, and made a guide about it, if you're interested).

Anyway, I think I'm resigned to the fact that PU are partially random/mystery :)

[light5_fl]

Yah, personal unions are interesting epsecially when your on the wrong end of one and they try to annex you... I won indepenence wars against france one time as england but got crushed and most of my country annexed as war spoils when playing ireland and I had to fight off the whole holy roman empire which pretty ruled most of western and central europe.

[RMassive]

Agreed that they can be really odd, and that claim throne is useless. In my opinion, they've gone a little too far to nerf PUs, although I am glad they arent as spammable as they were in the old days. I had a Brandenburg->Prussia game, and an RM with Russia. When the King of Denmark (who had all of Scandinavia) died, I got a chance to start a succession war with Russia, who had an RM with Denmark, and was my rival. This was probably the most fun war I had ever fought (I killed a frankly ludicrous number of Russians), and the enormous navy of Denmark was the best prize I've ever one. It just seems ludicrious that I could start a claim war with a country I had an RM but different dynasty from over another nation that I had no connection to (were actually my rivals). Yet when I have an RM with a country with no heir and I actually claim the throne, nothing ever seems to happen. I think I should at least get a member of my dynasty installed if the claim is uncontested

[Eroba]

Its something that the heir has weak claim so sometimes it is like in the disputet sucsession meny but if you hover over the king name its on monark death regency for Louis von Wittelsbach