From the Super Mario Wiki
Vinny is the brother of Tony and a member of the Pianta Syndicate. Although loyal to Don Pianta, he does not always agree with his decisions. During the events of Paper Mario: The Thousand-Year Door, the mobster Frankie and the boss's daughter Francesca elope, causing the Don to wish vengeance against the happy couple. However, Vinny wishes for Don to be happy for Frankie and Francesca's marriage. In the end, Don Pianta reconciles with his daughter and number one thug, and gives them command of the Pianta Syndicate.