When the Jerome crime family returned to Port Charles in 2013, Carlos Rivera relocated from Puerto Rico to Port Charles to serve as the family's operations manager. Carlos had worked for the family for many years and was privy to their secrets, including the knowledge that Julian Jerome was not deceased but gaining territory in town under the alias of Derek Wells. He also knew that the Jerome family planned to take over the territory which belonged to Sonny Corinthos and Carlos offered his expertise and assistance in the take-over.
In addition to his work for Ava and Julian Jerome, Carlos had plans to rekindle his relationship with Sabrina Santiago. Carlos was disappointed to discover that Sabrina was involved in a relationship with widower Patrick Drake but not undeterred. Instead, Carlos led Sabrina to question if Patrick would ever love her as much as he had loved his deceased wife. However, Sabrina remained committed to Patrick and made plans to marry him. On the day of the wedding, Patrick's presumed deceased wife returned and interrupted the ceremony. Sabrina was heartbroken and turned to Carlos for comfort.
Just as Carlos started to think that his chances with Sabrina had improved, he was taken by Sonny Corinthos and his associate Sean Butler. They intended to kill him in order to send a message to Julian until Carlos announced that he was related to Sonny's late wife Lily Rivera. Carlos claimed that he was Lily's half-brother and Sonny decided to keep him alive until he knew the truth. He was taken to Sonny's warehouse. As Carlos attempted his escape, Sonny and his men arrived and a gunfight ensued. Carlos escaped with a gunshot wound to the arm and reached out to Sabrina for help.
Sabrina hid Carlos at her apartment and he learned that she was pregnant with Patrick's child. Sabrina feared that Patrick would accuse her of using the pregnancy to break up his marriage to Robin and she planned to hide the pregnancy. Carlos stepped in and claimed that he had fathered Sabina's child. He described the life that he and Sabrina could have together if she would agree to his lie. However, Sabrina told Patrick the truth about her pregnancy and sent Carlos away.
Meanwhile, Carlos was torn between Ava and Julian when they each asked him to keep secrets from the other. Ava confessed that she had murdered Connie Falconeri but pinned the crime on A.J. Quartermaine. Carlos agreed to murder A.J. on her behalf but his plan was foiled by Luke Spencer. Around the same time, Julian was arrested for shooting A.J. and Julian asked Carlos to garner information about Ava's connection to A.J. When someone else shot and killed A.J., Julian was arrested and cleared. He suspected that Ava was involved in the murder and asked Carlos to garner information about Ava's connection to A.J.
Carlos remained loyal to Ava until the police discovered proof that he had broken into the Quartermaine mansion and attacked A.J. When Carlos realized that the evidence was mounting against him, he felt pressured to reveal that Ava had ordered the hit. Ava sensed that his allegiance was in question and she threatened to harm Sabrina and her unborn child if Carlos did not keep her secret. When Carlos received word that Sabrina had been involved in a car accident and given birth prematurely, he believed that Ava had carried out the threat. Although Carlos had not been involved in A.J.'s murder, he confessed to the crime to ensure that no further harm would come to Sabrina or her child.