Casey was introduced in the "Don't Stop the Music" storyline. She was Jamal Jenkins' cousin from Detroit, MI. She came to live with them, when her own mother went to pursue help and treatment for her struggle with being an alcoholic. She was a jokester who played pranks on Jamal and his family on occasion and really liked peanut butter. Furthermore, Casey met Ghostwriter midway through the aforementioned story arc and (presumably) became a member of the Ghostwriter Team at the end.
Casey returned in "Four Days of the Cockatoo". She was listening to Calvin Ferguson explain to them all that the bird Gaby recently found was a palm cockatoo. Also that it was illegal to have them in their country. Therefore someone smuggled it in. Not knowing what he meant, she thought he said snuggled. He very rudely looked at her and snapped saying: SMUGGLED!
Then she apparead again in "Attack of the Slime Monster," where she was wrote a short story based around a toy "slime monster" she recently received, Gooey Gus. Her story featured the entire team as they tried to find a way to battle Gooey Gus (since he came to life at some point in Casey's story).