Kat a short, skinny and dark-haired girl who has blue eyes.
She is British by birth (because her father is), but was raised in Italy (as her mother is Italian). Her family moved to England just a few months before the beginning of her first year. This makes her very self-conscious about her English skills, but it doesn't stop her being outgoing and particularly - sometimes annoyingly - talkative.
Her life in Italy was very ordinary and boring (it just consisted in her going to the Muggle school), but during the holidays, her family would always travel to some exotic place or famous city to visit it and learn everything possible about the place and the local culture. This helped to make her really curious about everything.
Despite her brain being very energetic and enthusiastic about every new subject, she is physically really lazy and this creates a quite funny contrast in her. Also, it's very easy for her to get bored about anything that isn't intellectually challenging.
When she received her letter from Hogwarts, she was enthusiastic, but also a bit disappointed that she wasn't getting to study at the muggle university she wanted to attend.
Anyway, what she's worried about is her lack of knowledge not only regarding the English culture, but also the Wizarding World (which she's trying to learn everything possible about before actually getting to school). She hopes this won't be an impediment in making friends in the new school, because she does really feel very lonely since she had to leave her old friends, who apparently she won't be able to get in contact with while at Hogwarts.