There's a conspiracy theory that part of Giuliani's famous takedown of the Italian mob in NYC was actually a takeover by the Russian mob who became much more prominent after their competitor mob was gone.

I'm not saying it's true, I don't know if we will ever get the evidence to say, but it's an interesting lens to view his later activities through, for example when he went to Ukraine to try to pressure Zelensky to investigate Biden, or when he tried to flip an election to favor the candidate Russia favors.