Isla is a student at South Park Elementary. She first appeared in the Season Nine episode, "Marjorine". She can also be seen watching the Jonas Brothers perform live in "The Ring" and later be seen sitting with the popular girls' clique in "Insheeption". She appears again seasons later and plays a much more significant role in the Season Twenty-One episode, "Doubling Down", where she and the other girls take Heidi out to dinner to celebrate her break up with Eric Cartman, but later begin to tease her and make her feel guilty. She plays another major role in the following episode, "Moss Piglets", where she is portrayed as one of the victims of Heidi's bullying.
Isla has wavy, shoulder-length dark brown hair, with a lock of it hanging down the center of her forehead; identical to Kal's. She wears a red sweater with green pants.
When dressed for bed, Isla wears a red nighthgown with white lace trim.
In the episode, "Doubling Down", Isla imitates Cartman to mock him and his relationship with Heidi, and does so near perfectly. This suggests that like the other girls, Isla may have a personal vendetta against Cartman, and speaks of him rather harshly.
- "Marjorine" - Seen with the "popular girls", playing with a cootie catcher.
- "Tonsil Trouble" - Seen in the background on the playground.
- "Breast Cancer Show Ever" - Seen watching the fight; background only.
- "The Ring" - Seen watching the Jonas Brothers.
- "Super Fun Time"
- "Butters' Bottom Bitch" - Seen in the hallways; background only.
- "Insheeption" - Seen sitting with the "popular girls".
- "Funnybot"- Seen from behind in the cafeteria.
- "1%" - Seen at Clyde Frog's funeral.
- "Cartman Finds Love"
- "Gluten Free Ebola"
- "Where My Country Gone?"- Seen on the playground.
- "You're Not Yelping" - Seen in the hallway.
- "Sponsored Content"- Seen in the hallway.
- "Skank Hunt"- Breaks up with Brimmy.
- "The Damned"- Seen in the hallway.
- "Wieners Out" - Seen in the stands at the volleyball game and in the cafeteria.
- "Douche and a Danish" - Seen making danishes in the school cafeteria.
- "Doubling Down" - Takes Heidi out to eat with the other girls. Teases her for her relationship with Cartman, although playfully, she unintentionally hurts Heidi's feelings when she imitates Cartman.
- "Moss Piglets" - Is verbally attacked by Heidi in the school cafeteria, and at the bus stop.