Sheridan is the much younger sister of Julian Crane, born when he was a teenager. She has always felt much closer to his son, Ethan, who is only a couple of years younger than she is. Her life was forever changed when she was an adolescent, first with the death of her mother, and then with her memory of finding a body shortly after. Her family has always allowed her to believe she killed someone that night for reasons that have not yet been explained. She was sent off to spend years in a Paris mental institute (Ethan was shocked to learn of this, as he was always told she was in boarding school), and later in her life, became friends with the late Lady Diana, the former Princess of Wales.
Sheridan returned to Harmony after being betrayed by her fiance Jean Luc, who wanted her only for her money (like so many others before him). She hasn't done much with her life up until now, always buying her way out of her problems. She couldn't do that when she crashed into Luis Lopez Fitzgerald's police car, and was sentenced to do 100 hours of community service at the Harmony Youthe Center. During that time, she flirted with and dated Hank Bennett, but it was Luis she fell in love with. It began in earnest when she followed him to New Mexico, hoping to prove Martin Fitzgerald was still alive, and was a certainty when Luis saved her instead of the man he thought was his father. (Turned out to be an imposter hired by the Crane family.)
Overhearing (yet another) imposter hired by the Crane family to "be" Luis claim he was using her, she decided, once her 100 hours was up (it took her nine months), to return to Paris. Unfortunately, in Paris, Roger and Pierre (the two most inept hitmen in history) are waiting for her. Luis followed her to Paris, and has saved her life more than once, but she still refused to return to Harmony with him. In desperation, he kidnapped her so he could get her safely back to the States. She had him charged with kidnapping, which almost resulted in the loss of his badge.
She continued to date Hank Bennett once back in Harmony, while still lusting for Luis. When it looked like the drug cartel followed her back to Harmony, the FBI assigned Luis to guard her (didn't really give him a choice). The two got closer and closer, even though Sheridan's dating Warren was a slight problem for them. Luis scared Warren off, leaving Sheridan alternately loving and hating Luis. Finally, in desperation, Sheridan went to Eve to hypnotize her about the night she found 'the body'. Her hypnotism seems to have revealed that she killed Martin Fitzgerald, but Eve convinced her that she was merely guilty about her mother dying at the same time, and associated the two events.
With this out of the way, Luis and Sheridan were finally free to be together...only the drug cartel, his hatred of her family, her family's hatred of his family, and her dating his best friend could have kept them apart. Despite all of that, the two finally admitted their love for each other, but before they could make love, Sheridan was shot and killed, leaving Luis heart-broken. But wait! It turns out she's not dead after all, and it was a plot by the FBI to make the drug cartel THINK she was dead. The only problem is that everyone who knows about the plan is being held hostage by the drug cartel, and she's in the casket!
Luckily Sheridan was saved from certain doom, and her and Luis finally got together. Unfortunately, their repeated attempts to become lovers have all been thwarted, the most recent by the revelation that Ethan is not a Crane. They finally managed to make it to the bedroom...and now they're headed to the altar! Luis has just become the latest in Sheridan's long line of fiancés. The wedding never went off when the tabloid sprung the news that Theresa sent the documents (although Theresa didn't do it, Sheridan believed it), and she and Luis went to Bermuda. After her body was positively identified after a boat explosion engineered by Alistair and Julian, Sheridan was believed dead.
After Sheridan's death, a young woman named Diana washed ashore in Bermuda, and was taken in by a fisherman named Brian O'Leary, his good friend Liz Sanbourne, and their friend Doc. They nursed her back to health, and slowly Brian and Diana fell in love. Unfortunately, Diana developed a gambling habit (one night's worth!) and lost thousands of dollars. Her markers were all bought by Nick Bozman, a former associate of Brian's. Desperate to save Diana from being in Nick's debt, Brian decided to go back to racing, which he had previously stopped doing when it became dangerous for his health. By the end of it all, Brian paid Nick off, he and Diana got engaged, and they decided to return to Harmony.
Once back in Harmony, it took Sheridan only one look at Luis' face to remember the love that they shared, and the two made love. Unfortunately, before she could break the truth to her new fiancé about her old fiancé, Brian (who was now known as Antonio) ended up in the hospital with a life-threatening illness. Rather than put Antonio's life at risk by telling him the truth, Sheridan elected to marry Antonio. She and Luis were prepared to tell Antonio the truth after a miracle drug saved him, but just then, Sheridan learned she was pregnant...and either Luis or Antonio could be the father!
Throughout her pregnancy, Sheridan and Luis continued to keep the truth from Antonio, allowing him to believe that his wife was carrying his child when the baby could belong to either one. Sheridan was kidnapped a few weeks before she was due, and kept in the basement of the Wallace home. Her baby boy was taken from her immediately after it was born, before Sheridan could ever learn it's gender, and after she escaped from drowning, she was led to believe her child was dead. She developed a strong attachment to Marty, the child Luis had with Beth, and it didn't take long before she was convinced that Marty was hers. This feeling became even stronger after Antonio died and she reunited with Luis, but Luis refused to believe it. By the time Sheridan was able to get DNA results proving that Marty was hers, Beth had fled town with Marty, and Sheridan refused to have anything to do with Luis until he brought their son home.
Shortly after Luis left town, Sheridan met Maureen and her son Mark. Hours later, Maureen was dead, the victim of the tsunami, and Sheridan was determined to care for Mark. Before Sheridan could even get used to her new role as surrogate mother she learned that Mark's father, Christopher Boothe, had come to town to claim him, and the little boy was really named James. Determined not to let James out of her life, Sheridan agreed to watch James while Chris worked, and before long, Chris and Sheridan became close friends as well, and Chris was there to comfort Sheridan when she received news that Luis had died. Slowly, the relationship between Chris and Sheridan deepened and as she fell in love with him, she agreed to marry him. Immediately after they married, Sheridan and Chris learned that the man Chris had rescued from Otto Krause's Hawaiian manse on their search for Marty was actually Luis.
When Luis awoke in the hospital, Sheridan agreed to marry him and even went through with the ceremony, never telling him that she was actually married already -- to Chris. He soon found out, and Sheridan tried to make it clear to him that her future was with Chris and his son James (and the baby she was expecting), but Luis was determined to get her back. He went to Rome to find Marty, and Sheridan was left in Harmony, dreaming of a future with Chris, James, Marty and her child with Chris.