She first appears as a stage girl like thing to her boyfriend's show, then hearing Dr. Schadenfreude complain about his lack of winning every year. She gets into a brief argument (which involves them slapping Dr. Shaudenfraude's hunchback) before they make up and Jaclyn slips into one of her pills to change into Dr. Glickenstein's girlfriend named Heidi, whom his Igor (and the main protagonist of the movie) has a crush on, unaware that she is just faking it. She later appears when she and Schadenfreude finds out that Igor had created the monster which is supposed to resemble life which she calls herself Eva. They chase the trio down the road, but fails. Jaclyn under Schadenfreude's commands turns into Heidi again, this time to give him the card that teleports him to Shaudenfraude's place. She gets frightened by Eva, but she then lies to Eva because she knows of Igor's feelings for her. She goes back and Schadenfreude kisses her before she eats a pill, turning her back into Jaclyn. Jaclyn gets so frustrated that she has to seduce every other mad scientists' girlfriend year after year to help him win and she tells him about Eva's desire to be an actress. She then turns into Heidi to seduce Igor to break Eva's heart to turn her evil and join Shaudenfraude. Igor rejects 'Heidi' for Eva before revealing herself to Igor. She joins in with Schadenfreude takes over the throne briefly. After Malaria is free from the evil storm clouds again, she last seen about to get her pills but she finds out that she is run out she transforms into a female hunchback.
She is a beautiful woman with fair skin, white hair, green eyes, red lips, a purple bowler hat, teal eye shadow, a light blue bow tie, a short black dress with purple sleeves, a short skirt, purple leggings and a veil on the bottom and boots. As Heidi, Dr. Glickenstien's girlfriend, she has red hair in pigtails, a Swedish accent and a Swedish dress that is purple and green. When she ran out of the pills, she is transformed into her true form a female hunchback with Heidi's pigtails.
- She has yet to return in a mystery, maybe with Schadenfreude.
- Jaclyn and her alter-ego, Heidi is a pun off the characters, Jekyll and Hyde.