Succession is the inheritance of a title. It is triggered when the current holder of a title dies or abdicates. The order of succession depends on the title's succession laws. They also dictate how titles are shared between heirs, if the late ruler had multiple titles.
继承人
An heir is any character who stands to inherit a title. If this includes the ruler’s primary title, they are considered to be their primary heir. Additionally, the player heir indicates with whom the player will continue upon death; unless they are of a different dynasty, this is the primary heir as well.
有继承资格的子女
The gender law determines which children can inherit titles. 
Bastards cannot inherit unless 
legitimized, their children can only inherit if born after legitimization took place. The following traits disinherit as well: 
bastard founder, 
devoted, 
disinherited, 
eunuch, 
order member, and any trait considered to be criminal.[1] Note that the progeny of disinherited characters still qualifies.
- Male only (agnatic): Only sons inherit titles.
- Female only (enatic): Only daughters inherit titles.
- Male preference (agnatic-cognatic): Daughters do not inherit titles if any eligible sons exist. Daughters with at least one son take precedence over daughters without.
- Female preference (enatic-cognatic): Sons do not inherit titles if any eligible daughters exist. Sons with at least one daughter take precedence over sons without.
- Equal (cognatic): Both sons and daughters inherit titles.
Realm succession
The realm succession law determines who will inherit each title without its own succession law.
Single heir
Every title is passed on to a single relative, keeping the realm fully intact.
Primogeniture
All titles are inherited by the oldest eligible child. Note that a dead or dishinerited child’s progeny takes precedence over younger siblings. If the gender law is set to male preference, male children of daughters are given precedence over their parent; vice versa for female preference.
If no living descendants remain, the title is passed on to the father in a patrilineal marriage, or mother in a matrilineal marriage. If this parent is dead, an heir will be sought in their progeny according to the same principles.
Ultimogeniture
All titles are inherited by the youngest eligible child. Note that a dead or dishinerited child’s progeny takes precedence over older siblings. If the gender law is set to male preference, male children of daughters are given precedence over their parent; vice versa for female preference.
If no living descendants remain, the title is passed on to the father in a patrilineal marriage, or mother in a matrilineal marriage. If this parent is dead, an heir will be sought in their progeny according to the same principles.
House seniority
All titles are inherited by the oldest eligible house member.
Multiple heirs
Titles are distributed among all eligible children, splitting the realm. If no eligible children exist, every title gets passed on to the oldest eligible relative within the smallest degree of consanguinity.
Confederate partition
- New titles, that are the same tier as the primary, will be created if enough of their de jure land is held.
- The oldest child is given the primary title along with the capital and any higher de jure title it belongs to.
- All titles, that are the same tier as the primary, are distributed in the order they're displayed, with priority given to the oldest child with the fewest titles.* Children, except the primary heir, are also given any lower de jure title. When a child inherits a title equal in tier as the primary, they gain independence.
- If applicable, all remaining titles one tier below are distributed likewise. Note that, except the primary heir, all children who received a title before are excluded from further distribution. When a child inherits a title that is lower in tier than the primary, they become a vassal of the primary heir.
- The previous step repeats itself till all titles are handed out.
- * duchy+ titles do not affect the number of counties you get.
(Regular) partition
- The oldest child is given the primary title along with the capital and any higher de jure title it belongs to.
- All titles, that are the same tier as the primary, are distributed in the order they're displayed, with priority given to the oldest child with the fewest titles.* Children, except the primary heir, are also given any lower de jure title. When a child inherits a title equal in tier as the primary, they gain independence.
- If applicable, all remaining titles one tier below are distributed likewise. Note that, except the primary heir, all children who received a title before are excluded from further distribution. When a child inherits a title lower in tier than the primary, they become a vassal of the primary heir.
- The previous step repeats itself till all titles are handed out.
- * duchy+ titles do not affect the number of counties you get.
High partition
- All children are divided into two groups: the Primary Heir and Other Heirs.
- Perform a regular partition, treating Other Heirs as if they were a single person.
- Titles that Other Heirs obtained as a group are then distributed among members of the group through regular partition.
- * duchy+ titles do not affect the number of counties you get.
Examples
Primary heir rules
The following diagrams denote the line of succession for the primary title. Squares are male, circles female. Only valid canditates are shown, ignoring the gender succession law. Black figures are deceased.
Partition rules
The following diagrams denote who of four heirs inherits each title. Higher tier titles are displayed above lower tier titles, and their de jure relationship is drawn out. The crown indicates which county is the capital. The black figure is the primary title.
Title specific succession
A title succession law can be assigned to individual titles—besides the gender laws, these are all a form of elective succession. Options are restricted to certain ranks, cultures and faiths.
Claim inheritance
The gender law determines which children can inherit claims. Bastards, disinherited and eunuchs never receive claims. Valid children are given a pressed claim on titles they did not inherit nor vassalize. If the ruler in question held pressed claims, each valid heir is given an unpressed version. Unpressed claims cannot be passed down themselves, but will become pressed if used in an inconclusive war.
- Male only (agnatic): Only sons inherit claims.
- Female only (enatic): Only daughters inherit claims.
- Male preference (agnatic-cognatic): Both daughters and sons inherit claims.
- Female preference (enatic-cognatic): Both daughters and sons inherit claims.
- Equal (cognatic): Both daughters and sons inherit claims.
Notes
- If an unlanded character inherits a title but no holdings, they will automatically usurp a county in their realm; preference is usually given to its de jure capital.
- With partition succession, anyone but the primary heir can be granted titles their siblings stand to inherit.
- If an heir already owns land within a certain title, they will inherit it before siblings who do not.
- Baronies are always inherited by their de jure count.
- The primary heir receives all wealth/gold and men-at-arms upon death.
- Characters with the trait devoted or order member can still inherit claims
- Disinherited characters can still inherit titles from rulers outside their dynasty
- The display order of titles in the character screen is decided as follows:
- The primary title always comes first.
- Higher tier titles come before lower tier titles.
- Titles of the same tier are ordered according to how long each title has been in possession, the oldest one coming first.
Tips
- With partition, one could grant children titles in advance for a major opinion boost—remember that a quarter of vassals’ positive opinion, or half of vassals’ negative opinion, is passed on to the primary heir (opinion of predecessor). As the house head, one can also modify their feudal contract with a weak hook.
- With partition, try and keep your domain within the capital duchy: every county within will be given to the primary heir as long as all siblings are given a duchy+ title. The same applies to kingdoms and empires.
- Relatives within the 3rd degree (extended family) can be asked for an alliance—this means a partitioned realm can be reunified as a federation.
- Characters above the age of 9 can be asked to take the vows, disqualifying them from inheritance; even married characters can be asked, assuming they're the patriarch/matriarch.