Cassie is depicted as being eccentric and suffering from several mental disorders - most notably, anorexia nervosa - and multiple problems, including low self-esteem, suicidal idealization, and drug addiction. Murray described her character as "very interesting because she has a lot of problems, and she's very troubled, and she's anorexic and completely lacking in self-esteem and self-belief, but along with that she's sort of quite smart. I think that she has quite a good reading on a lot of the other characters about what they're like and how they work and stuff, and I think she's a very clever girl, and she's also kind of silly and dreamy and quite fun at the same time as being a very tragic character."
The titular second episode of the first series and the penultimate episode of the second series focus on Cassie; the former focuses on her mental state and the latter focuses on her relationship with roommate Chris Miles.
The show's producers and writers discussed her character and described her centric episode in an interview with The Independent as about "how she gets through her day without eating, how she feels and what her tactics are", and campaigned to prevent any announcement of any Telephone counseling.
During the episode's credits, there wasn't a overall happy ending, because they "didn't want a little preachy drama where everyone hugs at the end"; instead, the producers hoped that people would recognize their own faults in Cassie. One reviewer described Cassie as being "as pale as Hamlet's Ophelia and arguably twice as mad".
Cassie's profile on E4's official Skins website.