Ivy De Vil pretends to be a sweet, kind, thoughtful and caring child (this even made the Dearly Family question how she could possibly be related to someone like Cruella by blood); though it doesn't take long for the Dearly Dalmatians to discover that her personality was just a ploy and that she exploits her kind persona in order to deceive those around her into believing she's purely innocent. Ivy tends to work for her relatives in order to help them achieve an objective, in which she uses her innocence as a means of getting past most people's suspicion; though Ivy also likes to use her innocent nature as a means of placing the blame for action on somebody else, even if it doesn't seem logical that they could have been responsible for the transgression.
While Ivy is initially subservient to her relatives, she gradually becomes more and more dominant and it doesn't take long before she starts bossing Cruella around, though Ivy's appearances in the series are rather infrequent. In order to make her innocence seem more believing, Ivy tends to speak in a very soft and polite tone, though she also walks around with a toy stroller, along with various other toys; though the stroller and toys are actually highly advanced technological equipment that Ivy uses to send information to Cruella and vice-versa. Despite the fact that Roger and Anita believe she's one of the kindest people they know, the Dalmatians realize they'll have to work extra hard to prevent her from succeeding in her schemes.
- Poison Ivy: Ivy helps her aunt in a scheme to buy the farm from the Dearlys by committing crimes and framing the puppies.
- Beauty Pageant Pandemonium: Ivy and Amber, Anita's niece, enter a beauty contest. Ivy forces her aunt to help her win by cheating, threatening she will report Cruella to the IRS fiscals if she doesn't. Cruella then bribes the contest staff, but failed thanks to the puppies. Out of anger, Ivy fulfills her threat.
- During this episode, whenever Ivy is nice, her pigtails are down, but whenever she is bad, her pigtails go up and almost resemble devil horns.
- Coup DeVil: following orders from the head of the family, Cruella hosts a family reunion so she and her relatives can think up plans to steal the Dearly Farm. Ivy is one of the relatives who attended the meeting, and the only one Malevola De Vil has sympathy. After Cruella momentarily manages to take over the Dearlys' land, she makes an agreement with Ivy in order to ensure Malevola will not become Cruella's next-door neighbor: if Ivy manages to turn the Dearlys' land inhospitable, she would become Cruella's heir. Ivy failed to make an asteroid fall on the Dearlys' land but somewhat remained as Cruella's heir.
- Ivy's change from good to bad is reflected by her clothing: her dress was blue when she was nice, but then turned red when she was bad. After this, her dress stayed either blue or red for the whole episode.
- Also, it is revealed Ivy is not so evil as she seems: she had chance to kill all her relatives letting an asteroid fall on the family reunion, this after Cruella signed the contract which turned Ivy her heir. It would make Ivy inherit all the family fortune at once, but Ivy saved their lives without thinking twice.
- It's arguable if there was the main inspiration source for Ivy's dual personality:
- Ivy shares the same first name and hair color scheme as Princess Ivy, a character from The Curse of Princess Ivy.
- Ivy is similar to Suzy Johnson, as she can be cute and innocent beside very mean as well.
- Ivy is also similar to Two-Face from Batman, as both have a two-sided personality - even symbolizing them with the color of their hair.
- Ivy is also similar to Minima De Spell, both being nieces of two great Disney female villains (Ivy of Cruella De Vil and Minima of Magica De Spell).
- Ivy can have been inspired by the character Shreeky of the 1985 TV series Care Bears: both characters have somewhat similar physical appearance and personality being both nieces of two great villains as well.