Faust: Deconstructing Shocker
Kamen Rider Build through its run goes back to it's earlier Heisei and Showa era roots for inspiration. But knowingly or unknowingly when creating the Faust organization they ended up deconstructing many of the tropes that Kamen Rider has used in its history. Even thought Faust itself was a minor speedbump a pawn in the greater scheme of things. It's influence can be felt through the series. Since this analysis is long and stressful enough with the edit lock breathing down my neck there will be unmarked spoilers ahead for episodes 1 thru 36 of Kamen Rider Build.
Takumi Katsuragi: From Dr. Shinigami to Kamen Rider
Katsuragi is known as the devil's scientist who fell because he began experimenting on humans. For those who are shocked a thing to notice is that Build is not part of the Decaido mess timeline created by the Neo-Heisei series. Even Toei was aware that the Skywall was too much of an asspull so the world of Build never had riders or kaiju or anything before Build came along. He started out as essentially the Dr. Shinigami. The Evil Genius who makes monsters but after Gentoku went crazier wanted out. Obviously his associates didn't like that idea and erased his memory, swapped his face, and dragged him into a conspiracy to continue making weapons this time as Sentou Kiryu. The hero/unwitting pawn of Blood Stalk. This set up is similar to Tsukasa Kadoya/Kamen Rider Decade ironically enough. But while Decade managed to free himself in the span of a movie Sentou is constantly being manipulated. Unlike Tsukikage and Dai-Shocker who are smug asshats who can even get Hijacked By DiEnd. Stalk is a competent villain and Build is a properly written show making a genuine difference. Even when Sento completely outwits and overpowers Stalk. Stalk still manages to turn the tables and pull out a win showing that even at the end he never escaped being Stalk's pawn.
Nanba Heavy Industries: The magical money tree
Jusaburo Nanba is actually the perfect example of the kind of sociopath who would willingly fund an organization like Shocker or Faust. He is a man with no concept of morals or empathy and is arguably the most evil person on the show since Evolt's full motivations have yet to be revealed. His existence also shows that evil organizations need sponsors. The fact that Gentoku had to keep Nanba happy or worry that he would cut off his funds was a constant concern for the organization. And the fact that Nanba dumped Faust and went to look for other business partners showed that for Nanba human life was worth less than spent ammo casings.
Blood Stalk: Fruit Satan
Blood Stalk AKA Evolt. A cosmic nightmare not unlike DJ Sagara. Hell for all we know he might be DJ Sagara. Stalk is essentially the man behind the man. The Budo of Build made even clearer in how the Evol driver uses copied forms of Build and Cross-Z similar to how Decade was originally made to be the destroyer of riders before Tsukikage decided to dispose of Tsukasa. Oddly enough Stalk is the one part that is most played straight. Also let's be honest he totally looks like Overlord Kouta when possessing Sento.