Cassiopeia is intelligent, cunning, and ambitious. She has many good aspects character wise, and also many bad aspects. She is smart, and if she puts her mind to something, she'll get it done. She is perseverent and prudent. However, she often lies and steals and will do bad things to get her own way.
She has glasses, dirty blonde hair, and bright blue eyes. She has a spattering of freckles on her face. Her hair is collar-length. Her ears have two piercings next to each other. She always wears a necklace from her mother, made of black string with a pearl on the end.

She grew up with her parents, Andrew and Miranda Rowle. They were both wizarding-born. She has an older brother, Marcus, who is a fifth year at Hogwarts, and three younger siblings, Charlene, two years younger, Gregory, three years younger, and Etamin, five years younger. Her family is rich, and she grew up in Ireland.

Her family first saw her magic when she was two years old. they were at a Muggle amusement park and Cassiopeia had already had ice cream earlier that day. However, she wanted more ice cream, but her parents said no. They were ready to go home. An active 7 year old boy, a 2 year old toddler girl, and a baby girl had tired them out. But Cassiopeia really wanted ice cream. She was so mad, that she made ice cream appear in her hand!