Committed adultery with Julian Crane while still married to Jonathan Hotchkiss.
Helped Julian arrange for the Luis imposter to keep Sheridan alive.
Kept quiet about Alistair's plans to kill Luis and Sheridan.
Both blackmailed and threatened to kill Julian to get him to marry her (twice now).
Planned to drug Theresa to keep her from manipulating Ethan.
Used her influence to have the Lopez-Fitzgerald family evicted as revenge for Sarah's death.
Used her influence to push Julian into signing away his rights to Little Ethan.
Poisoned Eve to keep Julian from divorcing her to marry his first love.
E-mailed Ivy's letter to the tabloids.
Involved in Alistair's plots to murder Sheridan.
Created the fake tape of Ethan shooting Julian.
Rebecca and Ivy Winthrop were friends since childhood. Despite having been married for over twenty-five years, Jonathan and Rebecca had only one child together, a daughter named Gwen. Rebecca was thrilled when Ethan and Gwen met and fell in love, because she always wanted her daughter to be rich and powerful. When she found out that Theresa and Ethan were involved, she immediately warned her daughter. Rebecca recognized the same lies and manipulations from what she herself had done as a younger woman...feigned friendship to steal another woman's man.
Rebecca's warnings didn't help, because Ethan postponed the wedding and began seeing both woman. After Gwen returned the ring, Rebecca was determined to get not only her daughter, but also herself in the Crane house, and get revenge on the little gold-digger for scheming to break up Gwen and Ethan's relationship in the first place. It's possible Rebecca saw her husband in Theresa, as he had once married her for her considerable fortune.
She began an affair with Julian Crane, the plan to eventually get him to ask her to marry him. When she found the proof of Ethan's paternity on Theresa's laptop, she used Theresa's e-mail to send it to the tabloids. Most recently she filed for a divorce from her husband so she could land Julian for herself. She married Julian in a quickie wedding ceremony after he signed the annulment papers with Theresa, but when it was discovered that Julian and Theresa had slept together, that nullified the documents, so Rebecca was out on her ear. Although it was eventually discovered that Julian and Theresa's marriage was invalid, there was no mention of the fact that Rebecca's marriage to Julian was therefore valid, and Rebecca had to blackmail Julian to marry her by threatening to expose Eve to her family.
Blackmailing Julian wasn't her only plan though. Rebecca decided to turn the tables on Theresa and make Theresa pay for everything she had done to Gwen over the years by taking her son away. She had an even deeper motive; she planned to arrange for Ethan and Gwen to adopt Theresa's son, to replace the child that they had lost. Although Rebecca came to care deeply about her stepson, she firmly believed he was better off without Theresa in his life, and knew that Gwen and Ethan could provide him with both love and stability. After child protective services deemed Theresa an unfit mother and the courts terminated her parental rights, Rebecca used her influence to get Julian to sign away his rights to his son and to convince Judge Reilly to approve Ethan and Gwen's adoption of the boy. When she learned that the baby Theresa was carrying for Ethan and Gwen could be the result of Theresa's rape of Ethan, Rebecca swore to finally get her vengeance on the girl who had caused her daughter so much pain. At the same time, Rebecca, desperate to keep her husband, began poisoning Eve Russell.
Rebecca never did get caught for poisoning Eve. When the case went to trial, with Eve accused of poisoning Alistair, Julian and Liz (who had drank the poison Rebecca had intended for Eve), Rebecca manipulated Julian into signing a document that promised he would never divorced her -- then took the stand and pointed the finger at Liz. Julian kept his promise to stay married to her, but spent his nights in Eve's bed. When Gwen became worried that J.T. Cornell would tell Theresa the truth about the tabloid article, Rebecca used her sexual past with J.T. to keep him quiet -- until Theresa offered him money.