Courtiers are unlanded characters.
Your courtiers can serve in many of the same positions as landed direct vassals: as council members, flank commanders (except in the Byzantine and Roman Empires), and holders of honorary titles. You have full control over their marriages and education.
Characters residing in your court include most of your courtiers, along with some other characters temporarily living in your capital while retaining their existing liege. The distinction between your courtiers and characters residing in your court is discussed in the final section of this article.
As of 3.2, it is possible to select in the game rules if you wish to be more implicated with court management. A big court might cost money to maintain, but it also add some new events.
You can often gather the courtiers you want through invitation, especially if you have high state diplomacy and likable traits. If a courtier will not accept immediately, calculate whether you can clear the necessary opinion difference for accepting invitations using gifts, seduction, or letting them educate up to two minor children or grandchildren. (In the character search window, characters that can be swayed by a gift will have a yellow horizontal hand instead of a red thumbs down.) With the Conclave DLC, enough wealth and the right conditions, consider buying a favor from the character and using it to force the invite to your court. This is the only way you can invite characters of another religion over to your court.
If they can marry, request to have them marry into your court.
As such there are two ways to look for courtiers - either filter by adults, not imprisoned, not rulers, and gender, or just "will join court: yes" and gender. The former is a chore to sort through, but includes the ones you grab with bribes favours or marriage. The later is a lot faster, and often enough has enough options to suit your need.
Furthermore, it's not enough for your court to be just capable, you also want it to be agreeable. And many of the potential courtiers that you'd need to resort to bribery for are NOT the agreeable sort.
Agreeable court means less plots and plot power against you, more plot power for you, and also means your courtiers more likely to stop (backing) the plots you don't want to succeed (provided you know about said plots in the first place). It's particularly important to watch for the attitude of courtiers with non-trivial intrigue, and it's especially important that your spy master likes you.
But, regardless of what you are searching for keep an eye out for high opinion courtiers. If nothing else, most of those can be used as temporary one-law councillors, and if they are both agreeable AND capable that's even better.
Talented councillors: Filter by male (unless culture, religion, gender laws, or game rules allow generic females to be councillors) then sort by skill. If your council power isn't "abolished" look for not just the best, but for "good enough" with high opinion. if your council power is rather high and they get to vote an a lot more than just laws, look specifically for capable ones (near the top of the skill list) with high opinion and agreeable traits (content being the leading one here).
A good practice is to re-run this search every five years or so to look for "upgrades". Especially if your council power is relatively high, and yet you still need a lot of laws pushed. Once you're ready for the next law look for good councillor candidates. Gather a few that you can upgrade, or at least re-place. Then take out the replacable ones, put puppets in their place (either loyalists or the ones you have favours from), push your law, then take out the puppets and put the replacements in.
Champion commanders: If you are expecting war anywhere within one generation time frame (which more or less translates to almost always), you may want commanders who specialize in army movement speed, siege speed, or combat. In addition to sorting by martial skill, consider searching by trait names such as "patient" or "organizer".
However, don't forget the marshal's "organize the army" task. Ideally you want to find the best marshal you can get your hands on, then look if there are any outstanding commanders available. If there isn't it might be better to let your outstanding marhsal find the new commanders instead of paying salary to mediocre ones. If there are, grab them, assign them as commanders and try to get your marshal to make them even better. Start doing this in peace time, long before you even know which war will be the next one, as it takes time and the more time it get the better results it provides.
Guardians: Having educators in your court lets you choose tutors for all your courtiers, and often for courtiers of vassals (such as their heirs). While you can get your own children and grandchildren educated almost anywhere, having the guardian in your court ensures they will not change the child's culture.
However, keep in mind that kids that don't have a guardian by default are assigned to your management (without occupying the ward slot) which, depending on your approach to playing CK2, could be preferable to having them be groomed by a skilled courtier with good traits. And the ones that already have guardians assigned will incur the "lost ward" opinion penalty towards you on their guardians if you DO re-assign them.
Alternatively, look for guardians that will change their wards religion or culture. There are multiple possible reasons to want those changed and education is a free and easily accessible way to do that (the only downside of the method being the time it takes for the generations to change).
Catholics may want to identify strong cardinal candidates or taxation-maximizing antipopes. Followers of Indian religions can steal other rulers' Court Gurus by searching for "mastermind scholar patient". With the Reaper's Due DLC, consider stealing courtiers with very high Learning to become your Court Physician.
Claimants: Press a claim for someone in a way that will make them your vassal, or arrange to inherit a claim for your dynasty's next generation. Claimants are generally willing to accept invitations if their current liege holds or controls the claimed title.
Heirs: Make your dynasty powerful by getting male heirs into matrilineal marriages with your daughters, and vice versa. Arrange for foreign duchies to inherit into your kingdom. Also consider pretenders, heirs of heirs, and anyone else who might inherit a title after a few murders.
Potential spouses and concubines: For whatever your goals are: quickly expanding your dynasty, eugenic breeding, gaining alliances and claims, or simply gaining prestige. See also Advanced marriage guide.
Bloodlines With holy fury DLC there's now power to be had in blood of others. But you need matrilineal marriage to be able to take that power and nothing facilitates acceptance of matrilineal marriage like having no say in the matter. Refer to the bloodlines page for more instructions including instructions for finding those bloodlines and their living members.
You can inherit money from rich courtiers in two ways. First, if they have no parents and no living progeny, you will simply inherit their gold and artifacts when they die in your court. Many lowborn characters, especially those with high skill, will earn over 20g during their time as council members. Gifts you send to these characters are great investments.
Second, if they have no valid heirs, you can grant them a county with the intent of making them lifetime administrators. Upon their death, you will regain the titles, along with any gold, retinues, and tech points. You can assassinate them to speed up the process. Or you can appoint an heirless old man with a middle-age wife, and let him die naturally. This is a good way to deal with counties in excess of your demesne limit (and duchies in excess of two) that you might want later.
You can also take money from rich prisoners by banishing them. If you have a valid reason to imprison someone, such as a known plot or excommunication, you can imprison and banish them once they are your courtier. If they are already your prisoner, but answer to another liege, you can invite their spouse and then banish them.
Last but not least, they make a decent choice when giving away titles. To develop holdings AI needs money. Instead of plotting multi-stage genocide to claim the occasional 150 gold, let them pour those 150 gold into your realm's lands. Especially if it's a new city you've just built in one of your core counties. Be warned however that AI can also waste money. That said, waste or no waste, the need for money is still there, and while money in AI pockets doesn't guarantee development, lack of money in AI's pocket will guarantee lack of development. Still, this is only a good move if taking money from them is somehow problematic. If you can easily take that gold then go ahead and do that. It's better to order new building in a vassal barony from your pocket than to count on AI to build it from their pocket.
Your court may grow through invitation, procreation, decisions that generate courtiers, and events. Banished characters and ousted rulers may also land in your court. If a courtier's marriage ends, they will often(?) move to the court where their parents live.
Your court will also grow or shrink due to marriage, because spouses move together when they can. A courtier who marries a ruler will move to the ruler's court. When two courtiers marry, the wife moves to the husband's location, or vice versa for matrilineal marriages.
Once you hit 30* people in your court, your courtiers receive reduced fertility. If you need a couple to produce multiple children, you may want to consider landing them. Alternatively, you could marry off some unneeded single adults to reduce the size of your court. (*Some mods may change COURT_SIZE_CHILD_PENALTY_THRESHOLD.) Additionally, a court with 25 or more courtiers is more likely to spread disease.
AI courts with 10 or more courtiers will be periodically "pruned" of "useless" characters in order to prevent the game from slowing to a crawl as time advances.. Characters under 40, with health at least 7, those with claims, and certain others (e.g. who caused someone's death, and immortal characters in mods) are immune to pruning.
Make sure to keep most of your courtiers happy - high-intrigue courtiers who dislike you can bring a lot of plot power to assassination plots against your ruler and family.
The player's court is not subject to pruning (the outright killing of courtiers in AI court), but unimportant characters still receive important penalty to health and fertility. The fertility decreases the number of children that characters can have by one. The health penalty does not affect anyone who has a living parent, nor anyone with a living spouse, a job, or an honorary title. It does not apply to children, or to characters of the court owner's dynasty.
Game Rule Court Size
If the game rule court size is activated, having a big court may cost money (0.5 gold/extra courtier). The court limit and can be increased and the court maintenance cost diminished with the majesty technology and the rank of your realm. Children and prisoners don't count. The game rule also accelerates courtiers pruning. It also allows expelling up to 5 several courtiers by decision when court limit is surpassed. It cost 5% of annual income (scaled, minimal cost 5, max 45). This will prevent prestige and opinion negative effect of normally asking courtier to leave court. The decision will allow you to review the courtiers before their leave. Beware that councilors and commanders can be accidentally removed this way, although it shouldn't expel any courtiers that you marked as important (if the code is believed, but it doesn't work, the decision will still expel characters that you marked important).
One of the safest and easiest way to get rid of useless courtiers would be marring them away. Obviously only works if they are adult and single.
Over the court limit will sometimes lead courtiers praising you for your hospitality. This can give the host 150 prestige and 15 piety upon accepting the praise.
Characters residing in your court
Your courtiers usually reside in your court, but so do several other types of characters. Characters also reside in your court if they are your prisoners, landed council members, or children being educated by adults residing in your court. You, too, usually reside in your court.
Characters residing in your court form their opinion of you based on your Personal Diplomacy attribute, instead of your State Diplomacy total. Residence location is also relevant for assassination plots and capture in sieges. Your courtiers who are not residing in your court are considered "abroad" and are listed in a separate tab of your character screen.
Lowborn characters and characters who don't have any family member (dead family members count, unsure if dead spouse counts) may leave your court and instantly die when your ruler dies. Consider marrying key councillors and commanders if they are such courtiers. This is the case of event/decision invited courtiers.