What metaphors are used in Vampire Academy by Richelle Mead?

The moment, when Dimitri Belikov (Russian Dhampir) meets Rose and Lisa in the beginning of the novel, his task is to return girls in the academy after their escape. But during the first meeting, Rose becomes to resist and attacks Dmitri. He says that she is a “wild animal”. But actually he doesn’t mean that she is a wolf or another animal. She doesn’t want to return school and decides to fight with him, showing her aggressiveness and disaffection. Rose’s character and inner power is revealed by this phrase.