It appears that Stella was an activist and environmentalist, as well as a vegan. In , she was seen protesting outside of Principal Folsom's office, lobbying for less of the cafeteria's mystery meat and more of vegetables, and any other health food. But her cries for the menu to be revised disturbed the principal, who was trying to have peace and quiet, and she stepped outside the office to confront her about it. Undeterred, Stella explained that she had to keep trying until she achieved her goal. Principal Folsom agreed, however, she still wanted peace and quiet most of all, and she broke Stella's picket sign in half.
Later, Stella was seen continuing her cause for change to get the word out, by passing out flyers to other students who passed by her. After they reviewed two photos with one featuring the splatter of grape jam on Raycliff's golf cart in the school's hallway, the other featuring the splatter of that same jam on Fiona Ashbury and her models, and evaluating the possible suspects behind those, Fillmore and Ingrid questioned her about them. Stella admitted to sabotaging the golf cart in disagreement and retaliation to the sheepskins that Raycliff had on the golf cart, but she denied exploding the jam on Fiona and the models, as Fiona used and showcased the material of the apparel that came from animal fibers according to a catalog for the fall fashion line-up. After finding the modem to her computer to be overloaded, Horace told Stella he was confiscating it. She told him she needed them to E-mail more people about a rally to save doodlebugs. He told her she would just have to do it the old-fashioned way: via regular mail.
Once finding out that Stella was in detention one Saturday with Wilbur, Grover Brady and Becca Baccadero, teaming up with them to get revenge for their being bullied and reviewing the suspects again, Fillmore, Ingrid, and Vallejo eliminated all of them except Stella. It was determined she was the one in the ninja outfit who fired spit-balls from a pitching machine, who ran across the rafters in the cafeteria, who Fillmore and Ingrid encountered earlier, and who almost ran into Wilbur in the school's kitchen. Horace informed the two Safety Officers he had a way of pinpointing the person behind these and they had him show them. In the Converted Center Control Room, Horace used a computer that featured a security system with a camera that's focused on the students in the school's hallway. On the monitor, the camera almost instantly zoomed in on Stella, who was scoping out through a pair of binoculars and wearing some foliage disguised as a potted plant. Fillmore and Ingrid then met up with her and Fillmore demanded she tell them where the three other bullied victims were. She refused and took off running. They continued through the hall, where the X Middle School Knitting Team were and Stella got caught in a large yarn ball, tumbling and bouncing into the control room before it came loose, and she was freed. Stella conspired with Wilbur, Grover, and Becca to get back at Horace for all the bullying he did to them even though he denied it, and they had him tied up in a rolling chair. Just as Wilbur was about to damage the control panel by dumping some gumbo from a pot onto it, Fillmore told them it was not the answer. He convinced them there are other ways to solve problems with bullies. From the monitor, everyone watched as Principal Folsom announced the winner of the quilting contest. Afterwards, the four did time in detention again, as revealed on the front page of the X Middle School Examiner.
Stella was a Caucasian teen girl with long, mustard blond hair and blue eyes. She wore a red bandana or head scarf, gray hoop earrings, olive green vest, teal, long-sleeved shirt with a folded collar, long, blue, double slit skirt with each split extending up to the lower leg, and brown sandals.
She is voiced by Shanie Calahan.