Htebazile "Eizzil" Enived, a.k.a. Negative Numbuh 49(-Temporary), is the Negative Universe counterpart of Lizzie Devine and a member of the Destructively Nefarious Kids, working for Eeballaw as one of his most trusted agents. Her whole name is Lizzie Devine spelled backwards.
Since she is the opposite of Lizzie, she is very mean and evil. Even though Eizzil is the opposite of Lizzie they are both loud and bossy.
She captures her positive counterpart and lures Nigel to the Negaverse, where she attempted to pose as Lizzie but Nigel wasn't fooled. Surprised by his deduction, Eizzil triggered a conveniently placed springboard that launched Nigel into the DNK treehouse.
Later confronting a chained Nigel, Eizzil learned from him that he knew she was an impostor when he looked into her eyes and he demanded the real Lizzie. As a confused Lizzie asked what was happening, Nigel cunningly suggested Eizzil's ex-boyfriend explain. Begrudgingly, Eizzil summoned Legin, who then boasted about their organization, the Destructively Nefarious Kids. Nigel soon proceeded to mock Legin, correctly suspecting he wasn't DNK leader. Eizzil attempted to punish him with a S.P.L.A.T.T.L.E., only for the Little Traitor Dudes For Children's Defense to appear and set their positive counterparts free. Though Nigel and Lizzie managed to escape, Eizzil and Legin later recaptured them and went into the Positive Universe in order to pose as their positive counterparts and convince Numbuh 4 to take apart the Energy Enhancement Grid in Sector V's treehouse.
However Numbuh 4 was able to figure out that he was being tricked when Negative Numbuhs 2, 3, and 5 arrived and Numbuh 4 saw that Negative Numbuh 3 wasn't Kuki. Numbuh 4 manages to beat up Negative Numbuhs 1, 2, 3, and 5 and send them back to the Negaverse, however he manages to somehow convince Eizzil to see the error of her ways and assist him in stopping his negative counterpart's plans. When Eeballaw enters the positive universe, Eizzil tells him to get off her friend's world and kicks him back into the Negaverse.
After Eeballaw is captured, Eizzil rejoins the DNK in the Negaverse and assures the Postive Sector V and Lizzie that they won't need help from their positive counterparts now that nobody is afraid of Negative Numbuh 4 anymore. As Positive Sector V leave, Eizzil hugs Nigel for complimenting her eyes, calling him "Positive Nigie" before he's taken back to the positive world by Lizzie.