Game concept
Involved
From the game's encyclopedia
When a Character or a County is Involved, it means they're considered a natural and integral part of a Struggle by the people of a particular Struggle Region. They benefit fully from the fluid advantages of Phases, and are the primary activators of Catalysts.
Cultures and Faiths that are considered Involved are those that have or had significant presence in the Region.
To be Involved, a Character must have both their Culture and Faith be Involved and have their Capital within the Struggle Region.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Involved is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "When a Character or a County is Involved, it means they're considered a natural and integral part of a Struggle by the people of a particular Struggle Region." It is part of Struggle. Patch 1.20.1.2, from game/common/game_concepts/03_fp2_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/03_fp2_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.