Dante is Sonny's son with Olivia Falconeri. Sonny was never told about his son. Sonny and Olivia dated as teenagers and she became pregnant after Sonny had left Bensonhurst. She kept the secret from Sonny because Olivia felt Sonny's lifestyle was too dangerous. She did tell the secret to her cousin Connie (Kate Howard), who was also involved with Sonny in Bensonhurst. Dante Angelo Falconeri was born in Bensonhurst, NY. He arrives in Port Charles as a hired gunman for the mob. It is not long before it is revealed that Dante is an undercover Detective using the name "Dominic Pirelli." He is trying infiltrate Sonny's organization to take Sonny down. To do that, he starts getting close to Morgan, who is immediately drawn to his new friend. Dante starts having relationship with Lulu Spencer, who is under Sonny's protection.
Dante becomes very close to Sonny and starts to witness many things that make him question going after the mob boss. He believes that Sonny is very good father. He tells Olivia that "Look, Sonny's a criminal, but he's a good father. He's great to his kids." Sonny has concerns about Dominic at the beginning, but quickly starts to see that Dominic has a lot of potential. Dominic saves Morgan's life at the carnival and for that, Sonny is eternally grateful. Dominic also saves Sonny's life in a shootout that goes bad. Sonny feels Dominic is becoming very valuable to the organization and even takes Dominic off a risky assignment that might get him killed. Dominic's performance so impresses Sonny that he thinks seriously about giving over "the business" to Dominic if he ever retires.
Michael overhears "Dominic" talking to Johnny on the docks and saying how he has a lot of evidence on Sonny and can put him in prison. Michael tells Sonny what he heard. Sonny doesn't believe Michael at first, but after some research, Spinelli confirms that there is evidence to arrest Sonny for the murder of Claudia and the evidence is coming from an undercover cop that has infiltrated the organization. Sonny and Jason make plans to kill "Dominic" for his betrayal. Sonny summons "Dominic" to the house for a job, but Dante becomes suspicious. When he realizes Sonny knows the truth, he tries to arrest Sonny for murder. Sonny pulls out a gun and shoots "Dominic." Olivia runs in and tells Sonny he shot his own son. Sonny seems in shock and tries to save Dante in the aftermath of Olivia's confession. Sonny starts asking Olivia questions and he seems overwhelmed by what she is telling him. He insists that he has to talk to Dante and try and make things right.
Dante is hired by the PCPD. He wants nothing to do with Sonny. He testifies in court at Sonny's trial for the prosecution. Sonny continues to try to establish a relationship with is Dante. After time, Dante starts to develop a relationship with Sonny and is not so hard on him. He realizes that Sonny has some traits that he can admire, but they will always disagree on issues with the law.
Dante gets shot at Sonny's warehouse when the Zacchara family tries to smuggle drugs into Port Charles. Dante is critically injured and has part of his lung removed. Sonny stays vigil at Dante's bedside. Sonny continues to try and establish a relationship with Dante.
Dante gets married to Lulu Spencer on December 23, 2011.
Sonny continues to try and be a father to Dante. When someone shoots at Dante, Sonny dives to protect him and takes the bullet instead. Dante finally realizes that Sonny is sincere in his feelings toward him. Dante comes to a new understanding and accepts Sonny as a father.
Dante and Lulu want to start a family. Maxie agrees to be a surrogate of their child. Dante and Lulu's child is born on August 21, 2013. However, it is revealed that Damien Spineilli is the biological father of the child.