I've watched ATWT for about 8 years, so I've seen Cady's entire run as Rosanna. The character existed prior to Cady joining the cast in 2002 and was played by one other actress from 1992-1999, but we don't care about her, so I'll skip ahead to the recent history. :)
Rosanna is an extremely wealthy (think billions!), successful businesswoman. Her father was very wealthy and she inherited tons of money and a car manufacturing company called Cabot Motors from him. She is/was the CEO of the company as well as the owner. Rosanna could buy and sell the whole town, basically. She's very powerful and well respected in Oakdale.
Rosanna's mother died when she was young. Rosanna came to Oakdale and was taken in by Emma Snyder (still on the show in a grandmotherly capacity) and lived at Snyder farm for a long time. Snyder farm is a bit of an ATWT landmark; almost everyone has lived there at some point, and Emma has been on the show forever. Rosanna and Emma always had sort of a mother/daugher relationship. Whenever Rosanna needs a place to hide or recuperate from any drama in her life, she runs to that farm.
Rosanna's only blood relation on the show is her older half-sister Carly. They only share a mother, so Carly is not wealthy like Rosanna. Rosanna and Carly hated each other for a long time (dispute over a man, Mike, who is no longer on the show). When Cady joined the show, Rosanna came back to town hating Carly. They were rivals for a long time and tried to screw each other over a lot. Eventually they made up, though, and now they're great friends and very supportive of each other.
Carly has another half-sister, Gwen, with whom she shares a father. Gwen is not related to Rosanna, but they like each other.
Rosanna has been married a couple of times to Craig Montgomery, a conniving menace that everyone loves to hate. During Cady's previous stints on ATWT, Craig was played by Hunt Block, Cady's real life boyfriend. They always had an amazing chemistry on the show... big surprise! :)
Hunt was (sadly, unfairly) fired from the show around the same time Cady left in 2005, but the role has since been recast (twice). The guy who plays Craig now is the original portrayer from back in the 80s. He just came back a few weeks ago.
During her first marriage to Craig, Rosanna decided she wanted a child. Due to an accident, she unfortunately had to have a hysterectomy (very beautiful dramatic acting by Cady - this is what won her that Emmy!), so she decided that she wanted to adopt. Craig agreed, and in an attempt to make Rosanna happy by getting a baby really fast, he arranged an illegal adoption in Canada. Rosanna thought the adoption was legitimate, so she naturally grew very attached to the baby, whom she named Cabot.
Craig, Rosanna and Cabot
Meanwhile, Rosanna struck up a friendship with Paul Ryan. They started off hating each other, but quickly became confidants and best friends. Paul was wrongly accused of murder, and Rosanna stood by him, posted his bail and helped him beat the charges. She was the only person in town who believed in him. Paul was a sounding board for all of Rosanna's problems with Craig. Craig ended up getting really jealous of Paul and Rosanna's friendship, even though nothing romantic was going on (yet!).
Rosanna bails Paul out of jail.
Rosanna eventually found out about Cabot's illegal adoption and was heartbroken. She considered leaving the country with Cabot, and even got as far as the airport (with Paul's help). But at the last minute, she changed her mind when she realized that kidnapping the baby would be wrong. She came back to town and handed the baby over to the Canadian authorities. This was another absolutely brilliant, heartbreaking scene in which Rosanna broke down in Paul's arms. She ended her marriage to Craig and told him she never wanted to see him again. She left town for a few weeks and went off to regroup and get her life back together.
Rosanna came back to town and received an anonymous message that if she could get Jordan (one of her employees; no longer on the show) to marry her, she would get Cabot back. She flirted and tried to get Jordan to sleep with her, but she failed and ultimately had to confess her motives to him. He eventually agreed to marry her to help her get her child back. Eventually it was revealed that Jordan was actually Cabot's biological father, and she tried to keep the information from Jordan, but he eventually found out. Then they found out that Jordan was James Stenbeck's son, and therefore Paul's half-brother.
There's so much James history and way too much to recap, but basically he's pure evil. He's the big villain on ATWT, and will go to any lengths to manipulate people and ruin lives. He's in prison most of the time, but he always escapes, wreaks havoc, and gets arrested again. He can do anything. He's Paul's father. Paul's mother is Barbara Ryan.
So, as it turns out, James was the one who sent the anonymous message to Rosanna and was the one manipulating her into marrying Jordan. Upon learning that Cabot was his son, Jordan insisted that he be part of the baby's life and pretty much refused to leave Rosanna alone. Ro really started to get irritated with Jordan and just wanted the baby to herself.
Okay, meanwhile, while stuck in the marriage to Jordan at James' insistence, Rosanna started to fall in love with Paul. He moved into her mansion to protect her and the baby from James, and they ended up confessing their love for one another. They made love and Rosanna immediately regretted it because she feared losing her son. This prompted Paul and Ro to come up with a plan to get James transferred to a maximum security prison in California. It was successful (or so they thought!), and Rosanna and Paul celebrated their freedom as Ro and Jordan ended their fake marriage. Paul even proposed to Rosanna and she accepted.
Paul and Rosanna's first kiss.
The first date!
Paul tells Rosanna that he's falling in love with her.
Paul and Ro confront James in prison.
Unfortunately their happiness only lasted about a day. James escaped during the transfer to the new prison and kidnapped Cabot and Rosanna. He took them to an abandoned cabin and planted a bomb in it. He put Cabot in one room and Rosanna in the other, and forced Paul to make the choice of who to save: the love of his life, or the love her hers. Paul only had time to save one of them, and he chose Rosanna. They escaped seconds before the bomb went off, and Cabot died in the explosion (or so they thought!).
Rosanna was furious and horrified that he didn't save the baby, and vowed never to speak to Paul again. She went to Emma's farm and mourned the loss of her child. Eventually she forgave Paul and they got back together and got married at the farm.
Paul and Rosanna celebrate their engagement.
Paul and Ro get married!
But once again, their happiness was cut short by more Cabot drama. On their wedding night, Rosanna found one of Cabot's shoes in the couch. Little hints of Cabot started appearing all over their house; someone was gas-lighting her. They first blamed Barbara, and later Paul's brother Will, but ultimately it was discovered that Emily was the one haunting Rosanna. Emily was arrested, claiming she didn't remember doing anything. (Emily was Paul's first love and was married to Paul's ex-stepfather, Hal.)
Paul comforts Ro after she finds Cabot's shoe.
Paul stares down Emily in jail.
It was eventually revealed that Barbara was drugging Emily and hypnotizing her and making her haunt Rosanna. Barbara was arrested.
Rosanna freaks out!
But James Stenbeck's only true weakness is his love for Barbara, and he couldn't let her stay in jail! So he planted a videotape of Cabot in Rosanna's house, proving that Cabot was alive, and that he didn't really die in the cabin explosion. He told Rosanna that her only chance at getting the baby back was to get Barbara out of jail by taking the blame for drugging Emily. So she did. But then James appeared in her house with Cabot and told her that if she didn't leave Paul, she'd never see her child again. James forbade her to tell Paul the truth, and said that he was not allowed to know that Cabot was alive.
Paul's wicked mother, Barbara, lets Ro take the fall for her crimes.
Rosanna finds the video of her son.
Rosanna had to choose between her love for her husband the her love for her child, and ultimately she chose her child. She couldn't let Cabot be raised by James. So she staged an elaborate breakup with Paul and broke his heart, then she went off with James and Cabot. Paul was devastated, thinking Rosanna never loved him. He became very bitter and cold and angry after she left. Paul then started up an affair with Emily.
Rosanna reluctantly tells Paul she never loved him and leaves with James.
Rosanna and James
A couple of months later, Rosanna appeared again - in Bangkok! James had her and Cabot stashed there, and was even talking about sending Rosanna to a Chinese work camp and stealing Cabot again, but Craig showed up (purely coincidental, heh) and saved them. James was arrested and Rosanna decided to give Cabot up in an anonymous adoption to protect him from James. She knew that if Cabot was with her, he'd never be safe. So in yet another emotional scene, Rosanna said goodbye to her baby and returned back to Oakdale with Craig. To this day, nobody knows where Cabot ended up.
Craig finds Rosanna in Bangkok.
Rosanna says a final goodbye to Cabot.
Rosanna came home and immediately wanted to rebuild her relationship with Paul. She told him the truth about why she left him, James' involvement, and that Cabot was alive, but she couldn't prove any of it and he didn't believe her. He was still extremely angry with her for dumping him, and basically didn't want anything to do with her. He rubbed his relationship with Emily in Rosanna's face and made Ro give up on any hope of being with Paul again, even though she still desperately loved him.
Paul tells Rosanna he doesn't care about her anymore.
Meanwhile, Jennifer (no longer on the show; now dead), Paul's sister, was pregnant with Craig's baby from a drunken one night stand. Jennifer didn't want Craig to be part of the baby's life, and tried to block him from having any rights. Feeling indebted to Craig for saving her life and Cabot's, Rosanna vowed to help Craig get joint custody. Because of Craig's bad legal track record, his lawyer advised him that the only way to have a shot at paternal rights was to marry Rosanna. Rosanna reluctantly agreed to the marriage after walking in on Paul and Emily having sex and being tossed out by Paul once again.
Rosanna tells Carly about Craig's proposal.
Rosanna and Craig got married, and shortly thereafter, Rosanna met Gwen (the aforementioned sister of Carly), who was also pregnant. Gwen didn't want the child, and agreed to let Rosanna and Craig adopt the baby. Gwen and Jennifer both ended up going into premature labor on the same night, and Jennifer's baby (or so they thought!) died. As it turns out, Craig switched the babies, and it was really Gwen's son who died. But Craig made the switch, allowing himself to adopt his own son. Jennifer mourned for her child, and Craig and Ro prepared to take the other baby home.
Craig and Rosanna get remarried.
Craig, Rosanna and Gwen
Rosanna gets excited about her new baby.
Rosanna inevitably found out about the baby switch, however, and was horrified. She confronted Craig, who admitted it, claiming he only did what he had to do to be able to raise his own son, but Ro was shocked and disgusted and immediately rushed out to tell Paul what had happened. Craig was right behind her, and chased her down the road in his car, eventually running her off the road and into a terrible accident. She was knocked unconscious, but woke briefly when Paul arrived on the scene and cradled her in his arms. She only managed to whisper a cryptic hint about the babies being switched before she lost consciousness again.
Rosanna learns that Craig switched the babies.
She was rushed to the hospital, where the doctors informed Paul and Carly that she had slipped into a coma and might not wake up. Paul sat at Rosanna's bedside and confessed his undying love to her, promising that if she woke up and came back to him, they'd never be apart again. Rosanna was whisked off to a special clinic in Switzerland, and that's where she's been for the past two years.
Carly says goodbye to her sister.
Paul vows to love Rosanna forever.
Craig was arrested for attempted murder and was sent to prison. Paul eventually found out about the baby switch (after decoding Rosanna's hint) and Jennifer was reunited with her child. Since then, Jennifer has died, Craig has been released from prison, and the baby (Johnny) has been taken away to an unknown location by Craig's daughter Lucy. Craig is still searching for them.
Oh, but also, Paul tried to keep the truth about the baby switch from Jennifer when he found out. He thought her life would be better without Craig's meddling, even if it meant she would never know her child. Paul eventually saw the error of his ways and told Jennifer the truth, and after a long time she forgave him. But Rosanna is going to be really pissed off about this when she finds out, both because she knows what it's like to lose a child and because she nearly died trying to get the truth to Paul.
Paul is now dating Emma's daughter Meg, and they're involved in a scheme with a wealthy businesswoman and fellow Craig hater named Lucinda (another very important ATWT veteran) and Emily's younger sister Alison. Alison's voice sounds very much like Rosanna's, and Paul had the idea to rattle Craig by having Alison make fake phone calls to Craig pretending to be Rosanna. It worked at first, and Craig believed that Rosanna was awake and making the threatening calls, but Alison just screwed up the plan by laughing during one of the calls, so now Craig knows it's a scheme. Meg is trying to act as Craig's confidant and get him to admit that he tried to kill Rosanna. He claims he was just trying to stop her, and that she was driving like a crazy person and that the accident wasn't his fault.
However, Craig hired a private investigator who confirmed that a woman matching Rosanna's description was spotted in Switzerland getting on a plane. It looks like Rosanna is going to make an explosive return to Oakdale and surprise everyone, even Paul.
So Cady's coming back to a quadrangle involving Craig/Rosanna/Paul/Meg. It's going to be really good. Paul/Rosanna are amazing together, and I cannot wait to see them together again!
Whew, that was long, sorry! Believe it or not, I left a lot of stuff out. It's hard to concisely recap so many years' worth of events. I know that's a hell of a lot to digest, so if anyone has any questions or needs clarification on something, I'm happy to try to answer any questions. All you really need to know is that Rosanna is AWESOME! She's got so many layers and different facets to her personality, and Cady really gets an opportunity to shine in this role.
If anyone wants clips, I have tons I can share. There's a lot of good stuff on Youtube too.
My Rosanna/PRo vids are here, and I can upload more. Also, everyone at the Paul/Rosanna board is really good about answering questions, so feel free to join us over there. Tell them Mads sent you. ;) My username there is VanillaRachel.