spontaneous expanded headcanons for the previous generation of the best aduna royal family:
Ardamin - Gimilzagar at this point - has a complicated relationship with his father. Earcalo, his older brother, is charismatic, popular, talented, strong-willed - and very Faithful. He uses the Quenya name intentionally. Gimilzagar is quiet, awkward, likes drawing and staying out of trouble. But he is a King's Man, ideologically speaking, and Calmacil would much rather that he take the throne and continue his legacy. He'll have more competent advisors, after all. And Gimilzagar wants to please him, but really resents that he only matters to his father as long as he can fulfill a role he hates.
Earcalo is engaged to Calairë, the oldest daughter of the lord of Andúnië. Calmacil's plan was probably to force the Andustalië to restructure their succesion in accordance with Aldarion's laws, which would force Earcalo to become lord-consort of Andúnië with some clever legal maneuvering, leaving the throne empty. Earcalo figure out what's going on and tries to have Gimilzagar disinherited preemptively on grounds of attempted treason, Zôrzimril has Earcalo assassinated, you already know this bit.
Calmacil is one of those people who seems very fatherly and warm in person, to everyone except his actual kids. And he's incredibly calculating. Used to be more of a hothead as a young man, grew out of it over multiple military campaigns. The plan comes first, always. He's actually a very good grandfather to Ardamin's kids, he doesn't have the same baggage with them as he does with their father and is just this sweet old guy with the cool sword collection who happens to be king.
Zôrzimril outmaneuvers his loyalists and throws his plans out the window as soon as he's dead, but that goes without saying. And Ardamin really hates politics.