Gloomy and dark-humored, Lizzy generally speaks in a monotone and is uninterested in the work of her fellow students. Despite this, she was a childhood friend of Franny Robinson and the two have remained friends well into the future. Her passion for caring for fire-ants would be reflected in her villainous persona in the video game's alternate timeline, where she has positioned herself as the queen of a mechanical ant hill referred as Hive. It also shows that she is one that holds onto a grudge, what with the whole thing having been set up by an accidental collision that ruined both of their Science Fair entries.
Lizzy is one of Lewis' classmates. Uncaring and bored by Lewis' failed Memory Scanner attempts early on, Lizzy later appears at the Science Fair with her fire ant farm, despite Mr. Willerstein's warning about fire ants being dangerous to people. During the chaos caused by Bowler Hat Guy, Lizzy makes a mischievous smile when her fire ant farm is broken on top of the gym coach. She appears again at the end of the film to see a successful test of the Memory Scanner.
After a mishap in traveling to the Science Fair, Wilbur Robinson accidentally sets into motion a growing rivalry between Lizzy and Stanley that culminates in the two of them becoming dueling supervillains in the future. In 2037 of this altered timeline, Lizzy has become an underground-based leader of a swarm of robotic ants terrorizing the city and clashing with Stanley's own machines. Wilbur infiltrates the hive to retrieve Time Machine #1, which was stolen when Wilbur first arrived into this altered future, only to lose it to Stanley's guards.
When going back to the Science Fair, he prevents himself from making the same mistake he did earlier and sets things back to relative normalcy before going after Bowler Hat Guy. Lizzy is the owner of a Pet Shop now.