Sister Larue was a nun of the Sisters of the Divine Magnatum.
Before she was Sister Larue, she was Dr. Linda Frank, mycologist. She was commissioned by I Thought You Were Hungry Foods, a major company in the agricultural industry, to oversee a project. That mission was, according to the Narrator, "the test tube conservation of the elusive Italian white truffle." She tried grating said truffle on three ITYWHF agents' pastas, but the experiment was a failure.
From Linda to Larue
What persuaded Dr. Frank into joining the Sisters of the Divine Magnatum was their truffle farm. So she joined the nunnery and became Sister Larue. When in solitude, Larue would experiment on the truffles. However, she needed some equipment for her labs. While searching, she found a secret door that led to the kitchen. There she met Hansel Von Getz, a Swedish cook, and fell instantly in love with him. In exchange for truffles, Von Getz would provide Sister Larue with not only laboratory equipment, but also forbidden items from the outside world for her fellow sisters.
After a few years, she finally succeeded in her mission. She decided to exploit this discovery for financial gain. Therefore, that day, she planned on leaving the Sisters of the Divine Magnatum. She gave the discovery to Von Getz. Unbeknownst to Larue, the Mother Superior had eavesdropped on her kiss with Von Getz. So Mother Superior sealed the doorway with bricks and wrote a breakup letter to Von Getz as Larue.
Father Ed attempted to save Larue's soul. But Larue fought and beat him all around the bell tower. In her final minutes, she looked out the glassless window of the bell tower holding her truffles. However, Pigby, the truffle hunting sow of the nunnery, snuck up behind her and pushed her out the window where she fell to her death.
She appeared in "Bad Habits".