Nicki was first introduced in the episode "Forbidden Girlfriend" as a rebellious, brainy student that he was tutoring because she was failing one of her classes. They secretly started dating one another and for a while it looks like they weren't going to get caught. Somehow, her vet father and Lois found out and forbidden them from dating each other. However, Malcolm and Nicki continued to defy them by dating each other in secret.
In the episode "Malcolm Holds His Tongue", Malcolm was tutoring her again and she was telling him a story about his life that he didn't care about. Malcolm, who was now thinking before he spoke, was thinking a lot of very rude things to say in response to her, but instead just said something nice. This made her feel happy with him and led to them making out again.
In the episode "Long Drive", Malcolm was once again hiding from Nicki's father in the closet. Lois started accusing Malcolm of still going out with her, which he strongly denied. Later in the episode, Nicki called Malcolm's house phone at the risk that another one of his family members would pick it up, because she assumed that out of all five of them, Malcolm would be the one who'd pick it up. Sure enough, she was right. They talked for a while and just after they stopped, Lois then took Malcolm on a long car ride, where she talked to him about sex and how it could affect with relationship with her. At the end of the car ride, Malcolm was talking to Lois as though he had admitted that he was dating Nicki, surprisingly, Lois had no reaction to this and they casually conversed about this, as though it wasn't a problem at all.
Nicki made her last appearance in the episode "Kicked Out", where she and Malcolm had another make out session in her room. She then told Malcolm that she wanted to talk about her problems for once, having barely talked to him about them before. Just when she started to talk about them, however, her dad came in and Malcolm quickly hid under her bed. When Nicki's dad accused her of having a boy over, Nicki angrily told him that Malcolm was hiding under her bed at the very moment. Her dad perceived this as a "snotty remark" and said that she doesn't need to be sarcastic with him. Malcolm eventually gets kicked out of his house by Hal for unrelated reasons and he goes to live with her. Nicki hides Malcolm in her attic, just above her bedroom and they plan on spending their lives like that. However, about a day or two into this charade, Nicki tries talking about her problems to Malcolm and he ignores her, only talking about himself. Nicki gets angry at him for only caring about himself and so she breaks up with him, leaving him locked in the attic all alone. Malcolm had to fend for himself for a while with her father's survival kit and goes crazy without Nicki. Soon, Malcolm broke through the floor of the attic and lands in Nicki's room, just as Nicki, Hal, and her dad are in there, busting them both. After that, she was never seen again.
In the episode "Forbidden Girlfriend", Malcolm comes over to Nicki's house to tutor her and they both fall in love with each other. Malcolm very quickly becomes Nicki's boyfriend and things go very fast for them as they instantly begin making out. Nicki was forbidden to be seen around Malcolm and much less date him, when her overbearing father figured out that he existed. This, however, didn't stop her at all as she continued to date him and make out with him as confidently as she would is she wasn't forbidden to do so. The flame in their relationship was mainly based off of the thrill of doing something they weren't supposed to do without being caught, but as Nicki described, she doesn't like Malcolm just because of that, she likes him also because he's smart, cute, and funny. In the episode "Malcolm Holds His Tongue", Malcolm is shown to care about himself way more than he cares about Nicki as she was seen complaining about her own personal problems to him, much to the unhappiness of Malcolm. Malcolm was thinking in his head all of these rude remarks that were basically him telling her to shut up, but he kept himself silent, having taken up a new habit of thinking before speaking, which got on Nicki's good side and led to another make out session. Malcolm's indifference to Nicki's problems were brought up again in the episode "Kicked Out", where Malcolm was seen complaining to Nicki about his own problems a lot, but he was completely annoyed with her complaining about her problems to him, despite her listening to him when he complained. This eventually led to Nicki getting annoyed with him and so she broke up with him in anger, telling him that he was egotistical and a selfish jerk. At that time, Malcolm was living in Nicki's attic because he was kicked out of his own house, and so Nicki coldly locked him in there, never to return. After the break up, Nicki continued the charade of pretending that Malcolm was never with her, just as Malcolm breaks through the ceiling and lands in her room while her father and Hal were present. Nicki was seen in total shock when this happened, and after that, she was never seen again.
Nicki hates her father and the two of them spend most of their time arguing with each other. Nicki's father only wants the best for her daughter and wants her to be safe. However, he comes on a bit too strong as he acts very strict and even angry when he tries to protect her, which only makes her angry at him. Nicki always disobeys her father's rules because she knows she can get away with it. She acts very sneaky and does everything he tells her not to do and does it so confidently, that it's almost as though she was never told not to do that. This was all until the episode "Kicked Out", when Nicki was busted for dating Malcolm and hiding him in her attic for multiple days and that was basically the end of her story.
While not as strong and hate-filled as her relationship with her father, Nicki's relationship with Lois is basically the same thing. Lois forbids Malcolm to be seen with Nicki, yet she ignores her rules and goes out with Malcolm anyway. Although they never directly interacted, this much is obvious. In the episode "Long Drive", Lois said that she knew that Malcolm was dating Nicki, but given that Lois had no proof, Malcolm continued to deny it. Lois got Malcolm in the car and had a long talk about sex with him. At the end of the conversation, Malcolm and Lois were casually talking kind of out of character, with Malcolm openly telling Lois that he was dating Nicki and with Lois being perfectly okay with that. In the episode "Kicked Out", when Malcolm and Nicki's relationship was officially exposed, Lois was at her sister's house and so she basically had no idea that this happened.
Nicki and Stevie are actually pretty good friends with each other. Nicki likes to mess with Stevie by finishing his sentences when he stops to breathe and says things about how beautiful she is. Stevie doesn't entirely like Nicki. He doesn't hate her as a person, he just finds her careless and rebellious behavior to be very unadmirable. Their only interaction was in the episode "Forbidden Girlfriend" and due to her breakup with Malcolm, it's not likely that they two of them are still friends with each other.
- She is Malcolm's third official girlfriend, with the first one being Sarah Coleman from the episode Malcolm's Girlfriend, and the second one being Alison in the episode Stupid Girl. She is also the fourth girl Malcolm has even made out with, with the first three being the same first three girlfriends as mentioned before.
- In the episode Forbidden Girlfriend, she briefly mentions that she has a little brother who is always ratting her out to her dad. Her little brother is never actually seen in the show or mentioned again.