Karen was a friend of Joe's neighbor Claudia in New York. She met him in passing a couple of times, including while Joe was on his way to Beck's surprise party carrying the special cake he had made her with the scrabble board spelling out "everythingship". Karen commented on it and said Beck was lucky to have a guy who cared. Another time, he sees Karen threatening Ron to leave Claudia alone with a baseball bat.
After Joe's breakup with Beck, Karen came onto him and they had sex, leading to a relationship between them. They were together several months and seemed to have a stable and healthy relationship. She referred to him as "babe", which he had mixed feelings about since he and Beck had made fun of people who called each other babe in a relationship. According to Joe, Karen was a neat freak and always keeping everything tidy, she was caring and liked to take care of him and others, she brought out the best in him, and they had a very active sex life.
While out together with Joe, they run into Beck who initiates a conversation with Joe. Karen asserts herself and dismisses Beck, and she and Joe continue on. She then asks Joe if that was "everythingship" girl, and he replies "ex everything". At a housewarming party for Ethan and Blythe, they run into Beck again. She greets Karen calling her "little Karen Minty", then apologizes saying she had been drinking. Making conversation, Karen gushes over Joe and what a great guy he is, specifically his relationship with Paco and how big his heart is. Beck excuses herself.
When it is apparent that Claudia has relapsed and is very sick, Karen refuses to take her to a hospital as she will lose her job and possibly lose her son Paco. Instead, she and Joe take her to his glass cage in the basement of the book store to detox and Karen stays with her to take care of her.
When Joe suddenly ends things, Karen is very calm and collected, to Joe's surprise. Although she was clearly hurt, she reasonably gathers her things and accepts the situation and leaves.
Later, she confronts Beck and thanks her for being her "get out of Joe free card". She says that she was aware of their lying and cheating while she and Joe had been together, and that Beck had shown her who he really was. She adds that she bets Beck is "no Candace", that he was still hung up on her in some way, and that he would one day do to Beck what he had done to her, or worse, "maybe he'll do whatever the hell he did to Candace". We do not see Karen again, however Paco angrily tells Joe that Karen was gone and not there for him or his mother anymore because of him.
- Relation: Ex-Boyfriend
- Relation: Colleague and friend
- As of Season 3, Karen and Marienne Bellamy are the only of Joe's love interests to survive their encounters with him.
- Karen is the only former girlfriend of Joe that he has not had an obsession with.