Stefano was introduced as Lee DuMonde's friend from Europe, a man who came to Salem to see his son, Tony. Stefano initially had no idea that he was the father of Lee's daughter Renee. Renee and Tony began a torrid affair, and when one of them wanted to leave, he faked a heart attack. Roman wanted to bring down Stefano for his illegal dealings, and had proof, but Roman was soon killed.

He was also behind the Raven killings. The Pawn was introduced in 1986, who proved to be John Black. John Black proved to be Roman Brady, with plastic surgery and amnesia. He worked for Stefano, and was involved with Victor, but unsure of what he did. Megan Hathaway was killed by Larry Welch, but Stefano blamed the Bradys because he was sure Hope had committed this act. He sought revenge immediately. He kidnapped Marlena. Soon Patch and Kayla encountered a boy, Benjy, on their honeymoon. They wanted to adopt him, but it turned out that the boy was Stefano's.

At the end of 1991, Stefano was assumed dead. Yet, Stefano returned some years later with son Tony and a brother and sister pair he treated like his own, Peter and Kristen Blake (he never adopted them). He knew of John's affair with Marlena, and revealed John as Belle's father at the baptism. The Brady's were in turmoil again. He opposed the match between John and Kristen, and set it up like John murdered him before he died again.

As a tribute to her father, Kristen married Tony. Tony knew Stefano was alive, but didn't tell Kristen. This ripped their marriage apart, much to the dismay of Stefano. Stefano reemerged again surprising Kristen, and the rest of Salem. Marlena then revealed her feelings for John. Kristen was afraid of losing John after the death of Tony. Stefano manipulated Kristen and she started scheming to keep her man. This involved Susan, the confused Southerner, and double for Kristen. She gave birth to Little Elvis, or John Jr., but either way, he was still Stefano's youngest son.

Roman returned on the day of John and Marlena's wedding, sick and confused. Kristen, thanks to Stefano, had found Roman, and he was dying. Kristen had said that John and she were married and that Marlena still wanted to marry him again. Stefano said he had the cure and John, Hope, Kristen and Hope trekked off to the jungle compound. And for once, he wasn't lying. He had the cure, and Roman's alive today. Stefano married Vivian, who he had control of thanks to a chip in her tooth. Stefano wanted the treasures her ex-husband, Jonesy, left to her because they actually belonged to him.

Stefano now has control over Hope and is using her to be Princess Gina his art thief and forger. Vivian is about to exact her revenge on him for implanting the emotion chip in her tooth. Stefano just found Gina on a submarine with evil John and now has to deal with that too. Stefano's plans with Hope didn't work, and he ended up dead.

While under Stefano's control, Hope slept with Stefano and became pregnant. Stefano wanted to make sure that "his child" (the child ultimately turned out to be Bo's) stayed in the family. He also wanted to win favor with his daughter Lexie, who desperately wanted to have a baby. Stefano hired Rolf's niece, Marlo, who was young, pregnant, often drunk, and about the same length along in her pregnancy as Hope to give her baby to Lexie. But, Stefano wanted Lexie to raise Hope's baby (whom Stefano believed to be his) so he switched the babies at birth. To cover up the switch, Stefano killed Marlo. But, her body was soon discovered and Stefano had to flee the country to avoid murder charges.

Stefano returned in the summer of 2007 to carry on his life-long feud with the Bradys. By then, he had sent his youngest son, E.J. to Salem to start wreaking havoc on the residents. Stefano's kidneys were failing so he ordered E.J. to impregnate a woman so that he could use some of the stem cells to heal his ailing kidneys. E.J. did as he was told, but stopped short of letting Stefano hurt Sami or E.J.'s unborn child.

As the feud between the Bradys and the DiMeras heightened (Roman was kidnapped and John was "killed") Stefano presented Sami Brady with a proposal- marry his son E.J. and the feud would be over. She agreed and the two were married. Stefano's happiness was short lived as E.J. was shot and wounded on his wedding day.

As E.J. regained his strength, he grew closer to Sami and his child, John Roman DiMera. E.J. sided with Sami multiple times against Stefano. This choice angered Stefano and he decided that he needed a new soldier as he could no longer rely on E.J. Through the miracle of soap operas, Stefano was able to obtain John's "dead" body and have Rolf bring John back to life and brainwash John. John became Stefano's new assassin/pawn/soldier. But, E.J. discovered John's body in Stefano's basement and told Marlena where John's body was. The police came and arrested Stefano. In retaliation, Marlena snuck into Stefano's cell and injected him with a drug that caused Stefano's body to act like it was in a comatose state. Stefano could not move or speak. But, he could still hear everything that was happening around him. When faced with the decision whether or not to try to revive Stefano; Lexie, Tony, and E.J. all decided that the world would be better off without Stefano. He was sent to live in a nursing home where he would remain in a vegetative state.

A few months later, Stefano did awake from the coma and set his revenge sights on Marlena. He orchestrated a dramatic hostage situation where Tony, Anna, John, Marlena, Kayla, Steve, Joey, Sami, E.J., Lucas, and Chloe were trapped on the 7th floor of the hospital. Everyone survived, but the police were unable to have enough proof to charge Stefano. So, he returned to the DiMera mansion, where he set about securing all of the DiMera assets. He had to fight his half-brother John and his children at different times, but he insisted that the DiMera name and DiMera family would remain strong.

Determined that his grandchildren would be part of the DiMera family, Stefano came up with a plan to remove Rafe Hernandez from Johnny and Sydney's life. He and E.J. hired a small time criminal, Arnold Feniger, to impersonate Rafe. They have him surgery to look exactly like Rafe and tutored him on all things Brady. When Rafe went into the hospital following a car accident, Stefano made the switch. Arnold went home with Sami and began destroying her marriage. Stefano gave Rafe a drug that would erase his memories and sent him to live in an institution.

Arnold would frequently meet with E.J. and Stefano to get direction and payment. Fay overheard one of those meetings. Worried that she would ruin his scheme, and thus cost him millions of dollars, Arnold killed Fay. Arnold tried to leave town numerous times, but kept getting held up. Meanwhile, Rafe escaped from the institution and headed back to Salem to try to get his memory back.

Arnold, Rafe, and Sami came face-to-face in the safe house. It only took Sami a few minutes to realize which one was the real Rafe. Sami and Rafe tied up Arnold and started putting together a plan to pay back the DiMeras. Bo and Hope soon joined the scheme. Together, they learned that Arnold was responsible for Fay's death. When Stefano learned that Arnold had been arrested, he made plans to leave Salem.

Arnold signed a deal with the police to testify against the DiMeras in return for immunity and witness protection. Just as he was about to give an official statement, some other inmates recognizes Arnold as Rafe and beat him to death. Stefano and E.J. were arrested for Fay's murder, but had to be released once Arnold's statement was no longer in evidence.

Stefano returned back to the mansion and his evil ways. But, E.J. insisted that he was going to change. Stefano insisted that E.J. was still trying to win back Taylor, and encouraged him to give up. Taylor made the decision for E.J. and decided to leave Salem. E.J. and Stefano decided to bring power back to the family name. Stefano focused on some old secrets that he shared with Alice Horton.

Bo and Hope found a "IOU" stuffed into a Horton family Christmas ornament. The "IOU" was from Stefano. Bo and Hope did more investigating and found that Alice had called in some favors to give baby E.J. medical attention. To show his gratitude, Stefano gave Alice the "IOU." She never needed to cash it in, but Hope did.

When John was framed for corporate embezzlement, everyone suspected Stefano. However, it turned out that E.J. was actually the one who framed John. Bo and Hope came to Stefano with the "IOU" and asked him to reveal details that would set John free. Stefano didn't give them hard proof, but pointed them in the right direction. John was set free and Bo and Hope were thrilled.

On Christmas Eve, Bo and Hope found a key hidden the the plaque at the town square. The key was for a safe deposit box and as it turns out, was a joint box that Alice had with Stefano. Bo and Hope went to Stefano to ask him to open the box. He refused at first, claiming that they would be opening Pandora's Box. But, Hope wanted to see what Alice's secret was. Stefano explained that there were two envelopes in the box. One contained a secret that Stefano had on the Hortons. The other contained a secret that Alice had on the DiMeras. Stefano agreed to open the box, but only if he was the only one to see what was in Alice's envelope. Bo and Hope agreed and Hope got the envelope that Stefano put in the box. Stefano opened his envelope a few days later, cried, and set a new plan into motion. The envelope contained proof that E.J. was not Stefano's son.

Inside Hope's envelope was a marriage certificate for John and Hope. The two had been married in Alamainia, during the time when Stefano had them under mind control. After getting some legal advice, John and Hope decided to travel to Alamainia to file for the divorce. Stefano followed them. While there, he had them drugged and held in prison until they agreed to go back under his mind control so that they could steal back a valuable piece of artwork.