Reworking Factions to be Engaging and Dynamic

No matter else can be said, the faction system does one thing very well, it reflect the incentive structures of vassals, in game vassals very rationally leverage the carousel of claimants to demand increasingly generous term and their personal powerbases thrive under weak kings.

Where the current system fails is in contextualizing these wars, particularly claimant wars, in the current system if vassal don't quite like you enough they are able start bloody civil wars with very little pretext provided, imagine if external war functioned like this where you could simply declare wars on same faith neighbors in the name of claimants half way across the world with the sole prerequisite being that you didn't have +80 opinion of them.

Just think of the downstream effects of requiring you to have +80 on succession with enough vassals to prevent factions, currently you either cheese it to the point where everyone loves you so much that you have to deliberately choose to maintain rivalries or you risk having your primary title taken and your vassal contracts being irreversibly fucked for at least a generation.

My proposal is the addition of Factional Casus Belli's or "Pretexts" which serve to cleanly address this. Essentially these are reflection of where you stand in regards to your vassal expectation of you as defined by their religious doctrines + tenets, and their culture ethos + traditions.

The idea is instead of requiring your vassal near total adoration, you can mostly skate by on their general apathy if you are the picture of an ideal king, survive with general approval if you fall reasonably short, survive with near total adoration if you fall significantly short, or end up embroiled in frequent civil wars if you are unacceptably out of line.

Here is a general outline of how this could work.

A ruler could fail short of the ideal granting a weak Pretext that will be used by anyone not generally happy with you(under say 40 opinion).

A ruler could have massive shortcomings or committed violations of religious norm granting a strong Pretext that will be use by anyone barring your adoring fans(under say 85 opinion)

A ruler could have done something unforgivable granting an absolute Pretext that will be use by anyone under nearly all circumstance barring only certain traits and relationships.

A ruler who is more than slightly disliked might see vassal joining faction with no valid Pretext(under say -10 opinion

Beyond changing the general game feel this can serve to provide some gameplay variety to different religions and cultures.

So for instance a playing over an Equal Fundamentalist religion with "vow of poverty" + "unrelenting faith" + "sanctity of nature" might potentially give vassal the Pretexts like the following

"Spouse of different faith" Strong PT
"Has over x gold income" Weak PT
"recently Had over x000 gold" Absolute PT
"Recent build 4+ level building" Weak PT
"Recently build 2+ barony building" Strong PT
"Recently built dutchy building" Strong PT
"Under 20 prowess" weak PT
"Under 12 prowess" strong PT
"under 8 prowess" absolute PT
"not Faithful after 1 years" weak PT
"not Faithful after 4 years" strong PT
"not Faithful after 5 years" strong PT
"unfaithful to spouse" strong PT
"recently caught sleeping with my spouse "absolute PT

While playing the exact same way over a Male preference Pluralist faith of "Pursuit of Power" "Pacifist" "Polyamory" might instead give a vassal Pretexts like the following

"Female Ruler" weak PT
"Unlawfully Revoked title of hostile faith" Weak PT
"Unlawfully Revoked title of astray faith" Strong PT
"recently at war for over 2 years" weak PT
"recently at war for over 5 years" strong PT
"recently at war for over 10 years" absolute PT
"recently white peaced hostile war" Strong PT
"recently surrendered hostile war" Absolute PT

Beyond adding gameplay diversity to question of how to prevent post succession civil war, this also serves to create a reasonable guideline for the AI selection of claimants to push during claimant wars.

Overall I believe that change like this could serve to turn the faction system into a more meaningful push and pull, instead of being always provided with the exact same problem of "your vassal don't like you enough" you instead get interesting problems like "your soulmate wife of a different denomination is seen as satan's influence, either convert her, divorce her, and prepare for war" or "you are expected to be x fame x month into your reign, so find a CB to start a war with major power, even an unwinnable one that you white peace out of later" or "Your lack of children is seen a divine ill omen" or "Your unhappy court is seen as reflection an evil soul" that's all before we consider how this provides natural complexity to manage big multi-religion empire without resorting to universal negative modifiers, and how the upcoming culture update could synergize beautifully with a more complicated faction system.