Julie first appeared in the Pilot episode. She was seen sitting next to Malcolm in his art class and complimenting him on how good he was at his work. She and Malcolm talked for a little, which got the attention of Dave Spats, who was possibly jealous, being in love with Julie too. Dave got revenge on him by making him sit in paint and staining his pants red in front of her. She was later seen, witnessing the fight that happened between Malcolm and Dave, watching in fear.
Julie made her first major appearance in Lois VS Evil, where Malcolm introduced her. He was so madly in love with her, that every time she talked to him, he would entirely misinterpret her and start thinking a million different thoughts about what the meaning of what she said was, even though the true meaning was as simple as exactly what it sounded like. In response to her, he would either freeze up, or he would lash out at her, assuming she was trying to toy with his emotions. Word spread quickly around Malcolm's school about Lois losing her job in this episode and everyone assumed that he was poor. Julie also misinterpreted this and so she founded a food drive in Malcolm's name and a bunch of other kids at the school, donated tons of food to him.
She appeared again in the episode Funeral, where she and Malcolm had plans to go to a Hanson concert together. However, Malcolm's plans had to be cancelled when his mom forced him to go to their Aunt's funeral instead. He called her back to call off the plans and she said she's take Jimmy Wescott with her instead. Assuming that this meant that she was going to fall in love with him there, he convinced Lois to cancel their plans for attending the funeral and then called Julie back and invited her over. When Julie came over, the house was a mess. Hal was listening to blasting music, Dewey and Egg were ruining the kitchen floor, and lastly, she walked in on Malcolm to see him in his underwear, she ran to the door and then tripped over the electrical wire and landed in the soapy floor, sliding into a spilled trash can. She began to cry and run away, hating Malcolm.
Julie was only in those three episodes and eventually disappeared in season 2. It was never really revealed why or if she shared the same feelings Malcolm had for her. Her last appearance was when Julie was disgusted by Malcolm and left him. It can be assumed that her disappearing was not fiscal and this was meant to be her officially leaving the show for in-universe reasons, despite the fact that she only appeared in three episodes.
Julie is a very happy and accepting girl who has a very high tolerance for both the world's groups of people and for bs. She is very nice and will go out of her way to express the biggest acts of kindness for even the smallest and most insignificant of people in need, such as founding a food drive for Malcolm, who she assumed was poor in Lois VS Evil. She is only annoyed when she is pushed extremely far, such as witnessing the horror of Malcolm's home in Funeral. Here, she freaked out and ran for her life and then started hating Malcolm.
- It may be possible that the school bully and aborted antagonist Dave Spath had a crush on her too, as in the Pilot episode, he was shown to be concerned when he saw Julie compliment Malcolm, causing him to pull a prank on him, making him sit in red paint.
- In the episode Funeral, it was revealed that she was a huge fan of Hanson, as she had a bunch of posters of them in her room and wanted to go to one of their concerts with Malcolm.