C.C. takes pleasure in creating conflict in the household and so is seen as something of a villain, albeit a comic one. In one of her first scenes, whilst at a party to get backers for Maxwell's new play, C.C. notices Fran coming down the staircase in an eye catching red dress, to which she condescendingly asks, "What's that?".
C.C. is the business partner of Broadway producer Maxwell Sheffield, having worked with him for almost 20 years. She harbors an intense crush on Maxwell and tries to move in on him after his first wife, Sarah passes away. A running joke is Maxwell's seeming obliviousness to C.C.'s overt romantic advances. C.C. is typically portrayed as a functioning alcoholic, as well as egocentric, mean-spirited, tactless and uncaring, particularly shown in how she never remembers the names of Maxwell's children Margaret, Brighton, and Grace.
Once Maxwell and Fran get engaged, C.C. plunges into depression, gains weight, loses her sanity and has to be institutionalized for a month. Finally C.C. accepts that her feelings for Maxwell are unreciprocated, and decides to re-evaluate her life.
C.C.'s main rival is Niles, the Sheffield's butler, who has despised her from the start, and frequently makes quips at her expense. Her parents are divorced, although her father Stewart is portrayed as amiable. When Fran comes to work as the new nanny, C.C. immediately views her as a threat for Maxwell's affection. She always refers to Fran as "Nanny Fine", even after Fran is wed to Maxwell and becomes the new lady of the house. C.C.'s Pomeranian dog, Chester, a gift from Maxwell, adores Fran but growls whenever C.C. is near.
During the final season of the show, the hatred between Niles and C.C. reaches its zenith; during an argument, their mutual rage turns to lust, and they suddenly start kissing each other passionately. Later, Niles finds that he can no longer effortlessly insult C.C. like he used to, and accidentally blurts out a marriage proposal. Once he is turned down, Niles proposes again several times, only to be rejected and mocked at each attempt. This situation becomes so intolerable that both C.C. and Niles declare they are terminating their employment with the Sheffield house and Maxwell's business, respectively. However, before Maxwell and Fran are able to talk them out of this decision, they stumble on Niles and C.C. in bed together.
C.C. and Niles marry in the series finale, as Fran is giving birth to twins. After they're being pronounced man and wife, C.C. learns that she is pregnant with Nile's baby, which causes both of them to faint. During the wedding ceremony, it is revealed that "C.C." stands for "Chastity Claire," which shocks everyone there except for the now love-struck Niles who tells her that her name is 'beautiful'.
She, along with Niles, accompanies the family to California.
C.C.'s despised Fran from the first time she set foot in the Sheffield home. She was extremely jealous of her attractiveness, and how Maxwell noticed her. However, Fran was also C.C's occasional friend in desperation.
After Fran and Maxwell's marriage, C.C. went insane and gained more weight, since there is no more hope of her being Maxwell's wife. But when C.C. realized she loves Niles, her relationship got better and better and better with Fran, and they both eventually became good friends.
C.C had an undying crush on Maxwell. She was one of Maxwell's college friends (when she was still a brunette and a bit plump) so they were friends, but nothing closer. In the episode The Producers, C.C accidentally blurted out to Fran that Maxwell should be her husband and Fran's babies should be hers. Maxwell, who walked in on them during this conversation, threatened C.C that if she and Fran don't become friends, he will end his business partnership with her. But when C.C realized she loves Niles, her obsession with Maxwell eventually ended, saying that Maxwell didn't have a chance with her and that she is "Completely, and totally, and multiply satisfied" with Niles.
A running gag on the show is that she never remembers the names of the Sheffield children. She once made a bad impression with Maxwell and wanted to use the children to fix her mistakes. She asked Gracie (by bribing her with money, but forgets her name when she wanted to write the check) but she said that she wants the big one, not the little one, so she asked Maggie, saying that she felt a special link with her, but messing it up afterwards by saying she danced on Maggie's wedding and then getting told by Gracie that she is not married, so C.C. had to go to Brighton, whom she then called "Trevor".
C.C. has experienced a few interesting things with the Sheffield children;
- C.C. once made Maggie dress exactly like her, but Maxwell said that it made her look 50.
- C.C. once met a man on the internet, with whom she and - as well as he - mutually enjoyed corresponding. He, however, turned out to be Brighton.
- Gracie said that (during Gracie, C.C. and Maxwell's trip during Christmas) C.C. misses Niles, conjuring a yes and no argument between them.
C.C. met Niles long ago when they were still very young. It is shown that ever since C.C. worked with Maxwell (she used to be his secretary before his business partner), he despised her, and would argue with her every time he would get a chance, joking about C.C. being a spinster, being old, being evil/witch-like, and being a man. Eventually, it became love, and Niles messed it all up when he proposed marriage to her. He proposed to her four times, but was turned down at every proposal. Niles eventually said that time is passing by her ("and it sucked" according to C.C.), and the man of her dreams is married to a woman half her age. Hurt, C.C. said to Maxwell that she's resigning the next morning. However, when Maxwell and Fran decided they wanted to convince Niles out of resigning, they found C.C. and Niles fast asleep with their arms wrapped around each other in Nile's room. Since then, C.C. began to have sex with Niles every time she had the chance (which is shown in a quote when C.C. is talking to Grandma Yetta, "Where? Kitchen, Closet, Stairway, Limo, Walmart?'), which eventually, led to her being pregnant.
C.C. rarely talks or interacts with Sylvia, but in one episode, she became friends with her when Sylvia and Fran are having a feud (calling her Syl). But when Fran and Sylvia apologized to each other, Sylvia said that "Please, it's over!".
When Fran and Maxwell went overboard on their honeymoon cruise, C.C. and Sylvia took a helicopter to see if they are still alive. They both have an argument when C.C. wanted to throw out Sylvia's "prescribed" candies because they weighed too much, but they were stopped by the pilot and apologized to each other.
C.C, Fran and Val would sometimes go to a singles club and just "hang-out", saying that they don't need men. However, like Sylvia, Val rarely interacts with C.C., only talking about her with Fran. However in one episode Val is seen as a great annoyance to C.C. after she becomes excited that 'Miss Babcock' knows her name.
Unlike Sylvia and Val, Grandma Yetta had a funny thing going on with C.C. Niles would sometimes joke about her being the same age as Grandma Yetta. Yetta once ate some almond cookies, which Fran bought from a Cantonese shop, that makes whomever eats it fall in love with the first person they see. She ate the cookie in front of C.C., and asked her how does she feel about going in a hot tub with her. Another one is during Fran and Maxwell's wedding, when C.C. and Yetta danced, and Yetta said that she would be lying if she said she wasn't turned on.