Kay is the middle Bennett child. She refuses to get along with her sister, teasing her constantly. She developed a crush on friend Miguel, and uses her best friend, Simone, and his best friend, Reese, to try to get closer to him. His growing relationship with Charity is a threat to her, so Kay has been doing everything to get rid of Charity, knowing she is her cousin. When Simone suggested that Charity's long-lost aunt might be her mother's sister, Kay did everything she could to make sure that the two never met -- her crush on Miguel proved more important to her than her mother's happiness.

Although she pretended to support Charity and Miguel, in reality, she was trying to keep them apart. After the incident in the mineshaft, Kay became more determined than ever to get Miguel...and sold her soul to Hecuba in order to get him. She helped Hecuba arrange for the demons of Hell to get their hands on Charity, but there's one problem...now the demons have their hands on Kay, too!

Kay was lucky enough to escape from the bowels of Hell and get her soul back, but her flirtation with goodness didn't last too long before she found the Book of Spells, and cast a spell to entomb Charity in a block of ice, and created a Zombie Charity to aid her in getting Miguel. Things seemed to be going okay, until Zombie Charity developed a mind of her own, and now has her own agenda!

While her plan has always been to get Miguel at all costs, even Kay isn't heartless enough to want her family dead to get what she wants. Zombie Charity has been threatening not only Miguel, but also Grace lately, and Kay is doing her best to convince Zombie Charity not to kill any of her loved ones.

Zombie Charity was defeated, but not before Kay committed the ultimate betrayal of friendship. She used Charity's essence to make Miguel think she was her cousin, then seduced him. Miguel was horrified and disgusted upon learning that he had actually slept with Kay, because he had no idea it was her. They found Charity a short time later, and while Miguel is thrilled to have his love back, Kay is still wishing her cousin dead. Not only that, but she is fighting with Grace as well, blaming her mother for all of her problems.

Kay watched the man she was obsessed with made plans to marry her cousin, and sought to destroy them at all times by threatening to tell Charity, even though Eve said it would be dangerous for her to know the truth. She also continued her verbal attacks on her mother, who would not help Kay in her schemes to destroy Miguel and Charity's lives. On Charity and Miguel's wedding day, Kay fainted at the Church, and everyone was shocked to learn Kay was pregnant!

Kay was thrilled that her condition resulted in the wedding being postponed, and despite Miguel informing everyone that he never would have gone near her, Kay is telling everyone that Miguel was meant to be hers. She is basing everything on something Miguel said once in the mine shaft, which is that if Charity never came to town, he may have asked her out. Recently she vowed to move out of the house after her mother gave her a choice...either follow the rules that Grace and Sam had, or leave. So to punish her mother for not helping her with her schemes, Kay left in the middle of a blizzard, putting both herself and the unborn child at risk.

Kay finally ended up at Tabitha's and blackmailed Tabitha into letting her live with her. Once she learned that Ivy and David were lying to Grace and Sam, rather than tell her parents the truth, she immediately began using it to her advantage, holding it over her mother's head whenever her mother wouldn't help her in her schemes to get Miguel. Kay also decided she wanted to learn to be a real witch like Tabitha, so that she could use the same evil she used to get Miguel into bed to break him and Charity up permanently. Unfortunately, nothing is working for Kay. Miguel is now wary of her after getting a glimpse of her dark side, and he is more in love with Charity than ever, even though Kay has just given birth to his daughter.

The baby's life was in jeopardy numerous times, but it didn't stop Kay from continuing her scheming. She even used her daughter's health crises in an attempt to manipulate Miguel away from Charity. Although she is no longer willing to kill Charity to win Miguel (because she doesn't want to end up in prison), she is still desperate to break up Miguel and Charity so that she can force him to be with her. She refuses to listen to Tabitha and Simone when they tell her that if Miguel is only with her by force, then it's not love. When her niece Sarah died Kay didn't care about the baby or her half-brother, only how she could use it to get to Miguel.

Kay continued to pursue Miguel, thrilled when they seemed to break up after Miguel caught Charity with Reese. Once she realized that Miguel was still dreaming about Charity and had no interest in her, she began plotting again full-force with Tabitha. Tabitha put a spell on Kay that turned her into a dog, and in that form, Kay went after Charity in Castleton, nearly killing her. When Miguel, trying to save Charity, speared the dog, it turned back into Kay, leading Miguel to believe he had accidentally speared Kay and not the dog. In the aftermath, Kay learned that due to the intensive medical damage, she could never have more children. When Miguel still refused to give up his love for Charity, Kay railed at him, blaming him for everything that had ever gone wrong in her life. It didn't make a difference; Miguel still left Harmony.

After Miguel left Harmony, Kay began to turn her life around. Although still living with Tabitha, Kay worked double shifts at the cannery to support herself and her baby daughter, and began to become a responsible adult. She started realising all of the things she had done wrong over the years, and although she did not confess the details, apologized to her father and sister for everything that had happened. She was devastated when her younger sister Jessica started smoking, doing drugs and sleeping with older guys, and was unsuccessful in getting Jessica to turn her life around.

After a few initially rocky encounters with Fox Crane, he and Kay began a relationship that became serious very quickly. Fox soon began spending a lot of time with Kay and her daughter, Maria, and Kay, wanting to do something wonderful for Fox, asked Tabitha to cast a spell that would make him successful in business. Unfortunately, she didn't listen when Tabitha warned her that she would have to pay the price for her request. Things started going sour when Fox all of a sudden began spending more and more time at the office, and more and more time with Valerie.

Valerie was finally out of the picture, and Kay and Fox were well on their way to a happy life together when Miguel came back into the picture. He returned home for Pilar and Martin's vow renewal, but decided to stay in town after giving up his search for Charity. He finally told her that he was in love with her, and although she tried to convince him (and herself) that Fox was the man she wanted to be with, she couldn't stop herself from being drawn to Miguel. She was horribly jealous when he got involved with a newcomer, Siren, and when she learned that Siren was really a mermaid she was terrified that Miguel would fall prey to the mermaid's curse, but no one would listen to her.