Sal Bonphenseiro was a member of the Dimeo Crime Family, beginning his career as a cat burglar which was how he gained his affectionate nickname of Pussy. He was in the crew of Johnny Soprano and supported Johnny through the unrest of 83 and backed Johnny's wishes to have his son Tony surpass him as capo of his crew.
During this time Pussy also forged friendships with Paulie Gualtieri and Silvio Dante. When Pussy did not have enough money to put his three children through college, he began pushing Heroin, despite being warned of the dangers by family boss Jackie Aprile who offered to help out with the financial difficulties, but Pussy feared being in debt to Jackie and passed up his friend's offer. When Pussy was caught he was forced with a difficult choice to face: thirty years in prison or to inform on Tony and his crew.
While Pussy chose the latter he initially tried to stay loyal to Tony by feeding the feds false information seen with actions such as helping Tony's protégé Christopher Moltisanti hide the body of Emil Kolar and not bothering to tell the Feds. When Tony got a tip from dirty cop Vin Makazian that Pussy was a rat, he ordered Paulie to investigate but made clear to Paulie he would only authorize a hit if a wire was found. Paulie took Pussy to a bath house and attempted to have him take his clothes off, however Pussy refused and went into hiding.
However he returned after the execution of Jimmy Altieri by Silvio and Chris, an execution which took the heat off Pussy as Tony believed Makazian had mistaken Alrieri for Pussy. While reporting to his FBI Handler Skip, Pussy remained reluctant over giving up information on Tony. when Jimmy Bones spotted him with Skip Pussy went over to Jimmy's house and killed him in order to conceal his secret .
As Pussy's jealousy of Tony's interest in new recruit Furio Giunta grew, his reservations about betraying Tony began to dissipate when Skip made Pussy wear a wire at the confirmation of Tony's son AJ. Instead of getting information about the business Pussy spent most of his time upstairs with AJ recalling how Tony stayed with his sister in the hospital until her death and assuring the boy of his father's love for him.
When Chris was Shot by Matthew Bevilaqua, Pussy saw it as an opportunity to earn back Tony's favor by tracking him down. Tony and Pussy drew out the murder talking to the frightened upstart for a while before unloading their guns on Bevilaqua.
Shortly after this Pussy gave up any loyalty to Tony and began to cooperate more. After having a portentous dream about Pussy's betrayal. Tony went to Pussy's house and looked for evidence while having Silvio distract Pussy with conversation. When Tony found a wire, thus confirming his suspicions, he and Silvio took Pussy out to a boat, where Paulie was waiting for them where the three men shot their old friend dead.