Cassie is shown to be a happy, friendly and caring girl. She is very feminine for the most part, but can be intimidating while angry. She is not cowardly and is very courageous. She peppers her speech with Scottish words and slang, such as "lassie" and cannae".
Cassie has pale skin, green eyes and red hair with orange highlights. Her original and main outfit is a pink skirt with flowers on it, big glasses, green stripes leggings and fancy white shoes. She speaks with a very heavy Scottish accent.
In the episode "Polish Power", when Team Aurora go to Poland, Zygmunt develops a crush on her, which she doesn't know about.
She and Aurora get along very well, and she is Aurora's best friend outside of the band.
In the episode "The Run to Russia", she develops a crush on Vadim Andreyevsky.