Michael's Biography (from ABC)
Michael "Sonny" Corinthos, Jr. (adopted father)
Caroline "Carly" Benson (mother)
Alan "AJ" Quartermaine Jr. (biological father)
Mike Corbin (grandfather)
Adela Corinthos (adopted grandmother, Deceased)
Richard "Ric" Lansing (adopted uncle)
Courtney Matthews-Morgan (adopted aunt)
Jason Morgan (biological uncle)
Emily Quartermaine (biological aunt)
Dawn Winthrop (biological aunt, Deceased)
Kristina Ashton Davis (half-sister)
Morgan Stone Corinthos (half-brother)
Michael Corinthos, III has been the center of numerous battles since the day of his birth. His mother Carly, lied about his paternity and claimed that his biological uncle Jason was his real father. Jason went along with the story, to prevent his brother AJ from learning the truth--that AJ in fact was Michael's father. Michael was born via emergency c-section after his mother collapsed and began to hemorrhage. Jason named Michael after his friend and local mob boss Michael "Sonny" Corinthos. Shortly after his birth, doctors discovered Michael had a heart condition that required immediate surgery. With Carly still in grave danger, Jason was forced to make the life-saving decision to allow Michael to have the surgery. Jason became a permanent fixture in baby Michael's life after post-partum Carly left Port Charles. Upon Carly's return, the Quartermaine family began to work her for access to their newest heir. At just three months old, Michael was kidnapped by Tony Jones and later rescued by Jason. Michael's paternity was eventually revealed to AJ by Robin Scorpio, Jason's girlfriend. This revelation led to a bitter custody battle between Jason and the Quartermaines. Although awarded joint custody, Jason chose to give up his rights so that his dangerous lifestyle would not harm Michael. The war over Michael came to a head when Sonny learned that Carly was pregnant with his child. Sonny blackmailed AJ into signing over his parental rights to Michael so that Sonny and Carly could raise their children as a family.
Over the years, Sonny and Carly would divorce and remarry numerous times. Throughout, Michael would come up with various schemes to reunite his parents-which often worked. Michael became a big brother with the birth of baby Morgan. Morgan is the son of Carly and Sonny. Michael would later learn that he also had a sister named Kristina from a tryst between Sonny and Alexis Davis. Michael enjoyed being a big brother, but his happy family would soon be shattered. Michael, Morgan and Kristina were kidnapped from their homes by Faith Roscoe. Michael put up quite a fight and managed to escape only to later return, because he could not bear leaving his brother and sister behind. Michael stole a cell phone off one of Faith's goons and called Sonny. During the call a gunshot went off, leaving Sonny and Carly fearing the worst. Jason, Sam, Carly, Sonny and FBI Agent Reese Marshall followed Faith's trail to Louisiana. After an intense gun battle in a church, Faith was taken into custody but the children were nowhere to be found. Morgan and Kristina were recovered at a nearby airport, but there was no trace of Michael. Jason later finds a picture of seemingly dead Michael on a sniper that was hired to kill Faith Roscoe. Sonny and Carly were inconsolable upon learning that Michael may be dead. Jason refused to give up and continued to search for Michael. Michael turns up alive on a private jet, only to have it crash off the coast of Georgia. When Michael comes to, he saves a trapped passenger from the plane. When he flips the passenger over, he discovers it is AJ. AJ begins to mess with Michael's mind and tells him that Sonny and Carly don't want him anymore. While stranded, Michael is bit by a scorpion and becomes seriously ill. AJ calls his pilot and has them "rescued." AJ and Michael turn up in the Bahamas where the mind games continue. Back in Port Charles, Jason fails to give up and tracks Faith's bank records to the Bahamas. Jason and Sam fly down to the Bahamas and discover recent pictures of Michael and AJ together. AJ flees back to Port Charles with Michael and they hide in the Quartermaine attic. Carly learns that Michael is alive, when she sees him in the park. Sonny, Carly and Jason go to the Quartermaines to retrieve Michael but he runs away. Sonny and Carly find him in the boathouse, but realize AJ has been messing with his mind. AJ and Jason get in a fight on the Quartermaine landing and plunge down to the foyer. At the hospital, Sonny and Carly try to reconnect with withdrawn Michael to no avail. However, Reese manages to connect and comfort him. Michael eventually recovers and reconnects with his parents. He has therapy to help him deal with the trauma.
Michael continues to experience trauma in his young life. His longtime nanny, Leticia is murdered. Michael takes the news very hard and insists that Sonny get revenge. Michael takes matters into his own hands. He buys a gun. It accidentally fires and the bullet hits Kate Howard, Sonny's girlfriend at the time. She survives her ordeal.
Michael continues to want to get into the business with Sonny and Jason. Sonny tells him many times that he wants Michael to take a different path. Hoping to be a good example to his son, Sonny takes Michael to the coffee warehouse to show him his legitimate business. There is a hit put out on Sonny and Michael gets caught up in the crossfire. Michael is shot in the head and put in a coma.