Edit: added a fair amount of information to my original response.

Sorry, like I said it's been a long time since I spent any real amount of time researching/reading about post-Soviet political economies of eastern bloc countries.

I can tell you that most of what I was reading was in peer-reviewed journals, which I'm sure are still available with the right keyword searches on LexusNexis....or Library Genesis.

If you aren't already, I would recommend checking out Vlad Vexler. Who is a Soviet-born, political philosopher/academic, outspoken Putin critic, and one of the better English language sources for intimate and nuanced explanations and analysis of the Russian political system, including the competing power structures and political dynamics of Putin's court.

He also provides some of the most thoughtful and considered arguments and analysis in support of Ukraine.

Edit (hope this helps):

Here's a keyword to jump start your search:

Silovik

That's the term for an elite within the intelligence community (FSB), or close ties to it (ex-KGB).

I asked Llama for examples of Siloviki who tried to amass power and influence outside their domain, and it provided me with this response:

Examples of siloviki who have tried to amass power in different fields and faced consequences include:

• Mikhail Khodorkovsky: A former FSB officer who became a successful businessman and politician, but was eventually imprisoned and exiled after he began to challenge the Kremlin's authority.

• Boris Berezovsky: A former KGB officer who became a wealthy businessman and politician, but was eventually forced into exile after he began to challenge the Kremlin's authority.

• Alexander Lebed: A former KGB officer who became a politician and governor of Krasnoyarsk, but was eventually killed in a helicopter crash under mysterious circumstances.

It's worth noting that the Kremlin's tolerance for siloviki accumulating power in different fields can vary depending on the individual and the circumstances. Some siloviki may be allowed to build significant business or political empires, while others may be subject to strict limits or even persecution.

To be fair, I haven't double checked the veracity for the people cited above, but only because even if their hallucinations, it aligns with how I understand their system of checks and balances to operate.

The system is setup this way, to give Putin the ability to play mediator when disputes arise and be the bridge between rival factions. So, he remains up top, and no one is capable of amassing enough power or influence to seriously challenge him.

It also means that Putin is not the arch-puppet master pulling all the strings as he's often portrayed in Western media. He sits a top the food chain, but his power over the elite comes from how he can exert, or finesse influence e.g. mediate disputes, not because he can slam a gavel and make everyone ignore their own self interests.