Magic Kitten: Sparkling Steps by Sue Bentley
Flame the magical kitten must hide in the human world to escape his evil uncle but he can't stay in any place for too long. In every Magic Kitten story, he takes on a new guise and seeks out a child who is in need of his very special help.
Olivia has not been welcomed by the other girls at her prestigious ballet school, who are jealous of her dancing. Then Olivia discovers loveable blue-grey kitten Flame and suddenly, magically, things start to look up . . .