Demetri is (initially) a member of Famiglia Bellone, one of the 12 ruling mafia families ("
Dodici Famiglie") of the wolf version of Italy ("
Siracusa"). He works directly for the son of Don Bellone and the underboss of the famiglia as his personal soldier, but his allegiance is ultimately with the head of the family. Don Bellone orders Demetri to create chaos around Famiglia Bellone's territory city Volsinii, essentially using him to act as a triple agent. Unbeknownst to him until much later, the Don actually intended to use his chaos to destabilise the city and pit all the famiglie against each other so they could wipe each other out (telling Demetri the intention was for Famiglia Bellone to come out on top).
During the chaos the Don poisons himself and dies, and Bellone's underboss severs his ties from the famiglia in order to create a fortress city with no mafia influence, leaving Famiglia Bellone both without leadership and vulnerable to the attacks of the other famiglie. Most of the famiglia are wiped out, and the rest scatter. Demetri and the few loyal remaining members of the famiglia decide to rebuild the family, and appoint Demetri himself as the new Don Bellone.
Demetri wants revenge on the underboss who wants to rebuild the entirety of Siracusa and rid it of the mafia completely, so he decides he will enter the new city, as mafia, and weaponise those laws against him. He also uses those laws to lawfully and legally double-cross another mafia family, and becomes the Don of that one too.
At his current canon point, he is lawfully the regional manager of 12 wineries within the new city ("Nuova Volsinii"), and unlawfully the Don of Famiglia Bellone and the acting Don of Famiglia Saluzzo.