Kate's past carries many scars and more than a few secrets. While married to the abusive Curtis Reed, she had two children, Austin and Billie. She had an affair with Dr. Bill Horton and became pregnant with Lucas. When Curtis found out about her affair and pregnancy, he beat her, threw her out and told her that their children were dead.
After Kate established a new and very successful life for herself and her son, she returned to Salem. She even married the powerful Victor Kiriakis, which brought her a place at Titan Publishing. Her past came back to haunt her when the presumed dead Curtis reappeared. He tried to blackmail her and then turned up dead. And Billie Reed was the prime suspect. During Billie's murder trial, it came out that Billie and Austin were actually Kate's children.
Since Curtis had been alive when Kate married Victor Kiriakis their marriage was invalid. This made Kate a target for Vivian Alamain, who wanted Victor back. Vivian made certain that all of Salem knew that Lucas was Bill Horton's illegitimate son. Vivian had herself in vitro fertilized so that she, not Kate, would carry to term the baby Victor wanted. Then, Vivian drugged an airplane pilot's coffee; Kate's plane went down and she was presumed dead for about a year. During that time, Kate was actually on a fishing boat.
Kate returned to Salem, arriving in time to see Victor and Vivian together in bed. Kate became enmeshed in a love triangle and a power struggle at Titan with Vivian. Eventually, Kate regained control and threw Vivian out.
Sami manipulated Kate by threatening to reveal that she was once a high-priced call girl and that she hired Franco to destroy Hope and Bo's relationship. She promised to stay silent as long as Austin stayed with her. Austin and Carrie married on the heels of the revelation that Will was really Lucas' son.
Sami got a taste of her own medicine when Kate framed her for Franco's murder. Lucas, the real murderer, felt guilty. Kate paid Nicole five million dollars to marry Lucas, so that he could get custody of Will over Austin and Carrie. When it was time for Sami to be put to death, however, Lucas ran in shouting "I shot Franco!" Much to Kate's dismay, Sami was released.
At Greta's coronation, Victor was shot and, presumably, killed. Kate returned to Salem the queen of Titan, but that didn't last long. Victor returned, at first haunting her as a ghost. Eventually, he came out of hiding and kicked Kate out - of Titan and his life. Kate got a job at a diner and used Philip to get money out of his father so she could get back on her feet. Eventually, this ultimate survivor got a job at Titan's competition, John Black's new company Basic Black.
Kate's life took a surprising turn when she began a relationship with Roman Brady. They exchanged vows on New Year's Eve, only to have Roman killed by the Stalker that very night. Kate was horrified when the identity of the Stalker was revealed. Marlena was responsible for Roman's murder, and she said she had done it all out of love for him. Little did any of them know that all the murder victims - and eventually Marlena - were alive and living in an exact replica of Salem on a tropical island.
Kate and John Black were both lonely and convinced themselves and each other that their loved ones would want them to move on, with each other. They shared some passionate kisses and were ready to make love when Bo burst in on them with the news that Roman and Marlena were alive.
Many of the "dead" Salemites returned home from their island prison. Billie was discovered there and came to town, as well, but Roman and Marlena were recaptured. When they finally headed back to Salem, it was just in time for John to propose to Kate. She accepted, but with the return of their partners, the engagement was off. John and Marlena and Roman and Kate were trying to renew their vows when Marlena fainted. Roman shouted, "Be careful, she's pregnant!" Much to Kate's chagrin, Roman was determined to stay by Marlena's side. Kate and Roman's marriage was over.
Kate turned her attention to trying to make the lives of her children perfect. One of her most important goals was to keep Lucas from marrying Sami. With a little help from Nicole and Tony DiMera, she learned that Sami had been "Stan" and in a dramatic move, she exposed this truth at the wedding. Unfortunately, who was waiting to pick up the pieces of Sami's once-again tattered life? Austin.
Kate figured out that Sami had assistance in saving Lucas during a snowstorm, and that EJ - on the run from the police - was that assistant. She planned on using this information to once again stop Sami and Lucas' wedding. Kate found a photo of Sami and EJ in Lexie's car on the night in question. Thanks to EJ, the photo ended up in the middle of a video shown during the reception. Lucas surprised everyone by asking Sami if she still wanted to be his wife. She said yes.
Daniel and Kate had had an affair and, after he began dating Chelsea, agreed to keep it a secret. Unfortunately, Chelsea did find out when Kate texted Daniel and she broke things off with him.
Kate was diagnosed with lung cancer. Daniel was her doctor. She needed a bone marrow transplant, and Chloe ended up being a match. Kate at first refused when she learned it could harm Chloe, but eventually accepted. Kate gave Chloe and Lucas her blessing to get married. Unfortunately, Chloe's involvement in Kate's treatment brought her and Daniel closer.
Chloe and Daniel had an affair, and Kate uncovered the truth. She told Daniel she knew he and Chloe had had an affair. She wouldn't say anything to Lucas if it never happened again, but if it did, she'd make him pay. Kate also told Chloe she knew about the affair. Chloe ran to Daniel for comfort, and Kate saw them kiss. She decided to poison Chloe and frame Daniel. She very nearly succeeded. Poisoned Chloe was in a coma, and Daniel was arrested!
After Daniel had Chloe injected with an experimental drug, she woke up and vindicated him and blamed Kate! Stefano helped Kate dispose of any evidence that she had poisoned Chloe and framed Daniel. In exchange, she agreed to marry him!
A disguised Kate broke into Madeline Woods' safety deposit box to steal important evidence against the DiMeras. She also learned something else: Madeline's son Chad's real father is Stefano! Eventually, she sent Chad his birth certificate anonymously.
When Kate learned that EJ planned on kidnapping Johnny and Sydney, she called Sami and told her as much. Sami went to the DiMera mansion and shot EJ. When it became clear that Kate had betrayed the family, she moved out. When Stefano became distraught over what was happening in his family, however, Kate returned to comfort him.
Kate and Stefano's blackmail marriage soon turned into real love. When Stefano fell ill with diabetes, Kate took charge and nursed him back to health. The two began pooling their resources to scam their enemies. Kate found professional happiness, too, when she relaunched Countess Wilhemina Cosmetics. Kate's main rival was the recent Titan acquisition, Mad World Cosmetics, run by Madison James. Kate and Madison were bitter rivals. Kate plotted to take Madison down by hiring Sami away from Mad World and getting Sami to reveal their secrets.
What Kate didn't know was that Sami had double-crossed her. She was working for Madison the whole time. When Madison realized that the situation was dangerous for Sami and ordered her to quit, Sami refused. Instead, Sami committed all of her attention towards making Countess W great.
An old flame of Kate's, Ian McAllister, came to Salem. He also happened to be Madison's husband. He told Kate all about Madison and Sami's plan. Kate toyed with Sami for a while and then fired her. Kate warned Sami that the police would be notified, sometime, but didn't tell her when. Ian tried to convince Kate to rekindle their relationship. She resisted at first, but when she mistakenly believed that Stefano was falling for Marlena again, Kate slept with Ian. She regretted it immediately.
Stefano was testing Kate the whole time. He was never after Marlena, but set Kate up to think that he was. When Kate failed the test, Stefano vowed revenge on her and Ian. He used his controlling share in Countess W to remove Kate as CEO and give the job to Sami. He also removed Kate and Lucas as heads of Hearth and Home. Finally, he kicked Kate out of the mansion.
Ian gave Kate the position of co-CEO with Madison of Mad World. She reluctantly agreed to work with her nemesis. Kate also continued her relationship with Ian. What she didn't know, but what she learned in the aftermath of the explosions in Salem, was that he was still in love with Madison.
When Stefano was shot and killed, Kate was considered one of the suspects. When it was revealed that Stefano was in fact very much alive, Kate tried to see him, but he refused, then disappeared.
