Logan’s partners as mirrors of the siblings
I’ve had this theory for a while that Logan’s primary partner in each season is a narrative mirror of the sibling whose “season” it is as prospective heir. I think 4x04 made the parallels more explicit with the return of Marcia and the scene between Kerry and Roman.
Marcia and Kendall
Marcia begins the series as Logan’s wife, and Kendall as his heir apparent. In the first episode, Kendall is viewed by the financial world as the natural successor to Logan. Logan resents Kendall for being a concrete possibility for a future after him.
In “Tern Haven,” Logan turns his disdain for feeling forced into choices onto Marcia. Naming a successor is “not how [he does] things”. Nan Pierce’s comment that Marcia is “a credit” to Logan is soon followed by his having an affair.
Kendall and Marcia hold similar positions in 4x04. They were estranged from Logan, but were still his wife and successor on paper. Now that Logan is dead, their legal positions are all that matter in terms of securing power.
Rhea and Shiv
Soon after Shiv becomes heir apparent in season 2, Rhea is introduced as a challenger. The two are both outsiders to the company. Shiv has been in politics for all of her adult life, while Rhea has worked at PGN. Shiv and Rhea are unique among the main cast of characters for being liberals.
Because of their time spent outside of Waystar, neither know the details of the Cruises scandal. Shiv alleges that she knows nothing.
Rhea and Shiv's similarities also have a visual component. In contrast to Logan's other partners, Rhea has lighter hair that she wears in a bob like Shiv.
Kerry and Roman
This one is probably the most obvious comparison. Viewers have been pointing out Kerry and Roman’s frequently matching wardrobes since season 3. They also spend season 3 as Logan’s primary partner and most likely heir, respectively.
Though Roman is the middle sibling, he is viewed as emotionally immature and unserious by most of the other characters. This emotional youth translates to literal youth in Kerry. All they can offer to Logan is unconditional love, which is useful to him personally, but not publicly. Kerry could never be Logan’s wife, because their relationship is obviously exploitative. Roman could never be Logan’s successor, because Logan “thinks there’s something wrong” (3x09) with him.
Kerry and Roman also share the subtext of being “not real people.” The concept of “No Real Person” in Succession is often tied to sexual coercion. In other instances it is tied to racial and class-based violence, the latter of which is also applied to Kerry in 4x04. Among the first people that the term is applied to the series are sex workers murdered aboard Brightstar cruises. Kerry is treated as NRP in 4x04 because she isn’t upper class (works as an assistant, lives in a “little apartment”) and isn’t legally married to Logan. Kerry pays for Logan’s crimes as a billionaire exploiting the love/loyalty of an employee 50 years his junior by being thrown out of the wake. She is treated as “distasteful,” an ugly reminder of another wrongdoing Logan was never even challenged over. I think its common knowledge here that Roman is implied to be a CSA survivor—I’ll link to an article that details this in more depth. Like Kerry, Roman is viewed as “dirty” because of what has been done to him by other people who almost certainly faced no repercussions.