Ultima/Chronology

Scarlet Bond
Violet serves as a minor antagonist of the film, being Lacua's master and the creator of Towa's cursed tiara. When Diablo learns of the tiara and the magic circle polluting the waters of Raja, he confronts Violet, suspecting her involvement. After some banter between the two, Violet reveals the details of her connection to Raja's royal family. Diablo then requests that she leaves Raja alone, informing her that Lacua had acted outside her orders and violated the contract she established with the royal family. Fed up with Diablo's attitude, a fight breaks out. While the two are relatively even at first, the magic body Violet created for herself begins to disperse. Though Violet desired to keep fighting, both her servants stepped in and convinced her to withdraw. While leaving, she learns the identity of Diablo's master.

Later on, when Rimuru has Lacua at his mercy, Lacua attempts to bluff his way out of trouble by using his master's "name". Just then, Violet contacts Lacua, disparaging him for his rash actions and abandons him. When Towa sacrifices herself to save Hiiro, Violet resurrects her as thanks for the entertainment she and her ancestors provided her, and also as an apology for Lacua ruining their contract.

Trinity in Tempest
Following the events of Scarlet Bond, Violet takes an interest in Tempest and enters the material world, taking the form of a cat to conserve her power. To enter the country, she sneaks into Nemu's bag, due to finding it suitable at the time, and spends the next several days travelling through human lands with the main trio. Though she has taken an unexpected detour from her original goal, Violet finds no problems and is enjoying her life as a cat, much to the distress of her two close servants who wish for her return to her domain.

At one point during her travels, she considers assisting the main trio when they're overwhelmed by Orthrus, but decided not to when Touka shows up.

Hero Awakening
Violet is recruited by Diablo who is looking for subordinates to help out with his "chores". At first, Rimuru thought she wasn't strong but Raphael quickly corrected him. Violet energetically introduces herself and pledges her loyalty to the demon lord. Her mannerisms and appearance were so cute that Rimuru doubted she was a daemon at first.

She gained a physical body by inhabiting one of the many golem skeletons prepared by Rimuru, each fitted with a Pseudo Soul. Her skeleton was slightly modified by Rimuru to retain her beauty, gold being mixed into it and turning the magisteel into orichalcum. After successfully completing her incarnation, she along with her two hundred soldiers were given names. Her two closer servants were named Veyron and Zonda. Ultima and Veyron evolved into Daemon Lords while Zonda's limit as an Arch Daemon was released.

She was then assigned to be Chief Prosecutor of the Public Prosecution Office in Tempest. Ultima accepted the job happily and looked forward to it. As shown in The Ways of the Monster Nation, she is seen frequently patrolling the streets and cracking down on crime.