Greetings counts and dukes! Today Paradox bring us The Royal Court from a different perspective: your perspective! It is not always you that will be the king, but it's other dynasties, to whom you will give tribute and ask for help.
Player vassals can approach their King-or-above ranked Liege with a Petition at any time through a new decision, providing they have enough Prestige, there is something they can ask for, and they haven’t done so in the last 5 years. Lieges will currently only interact with this content if they happen to have a player as their vassal and they make their own—no doubt outrageous—requests.
The possibilities include asking for a position on your Liege’s Council, asking for a Title you hold a claim on, or dismantling an unruly Faction in your own realm. There are currently 14 different options, each having some equivalent in the Hold Court events brought to Lieges by AI vassals, ranging from helping you convert your lands to paying off your debts.
This will allow you to ask for things directly without resorting immediately to war, which can remain a last resort for when you need to topple said king or emperor.
It is up to the Liege whether to receive a Petitioner, though outright refusing will damage relations and be seen as slightly tyrannical. The request itself may also be rejected once heard, and the odds of acceptance by the AI will be tipped more in your favor if you make reasonable requests and maintain good relations.
However, your Liege may also ask for something in return for granting your Petition, such as a Favor Hook or a bit of Gold—a counter you can of course reject, leaving you both empty-handed.
If a Liege is not being very forthcoming, you can also attempt to convince or outsmart a trusted advisor as a last resort, at the cost of some Prestige. You will need to pass a skill check in a relevant area, usually against one of your Liege’s councilors, or have an ally near to the throne, whose assent will force your Liege’s hand.