Solve the Riddle

A little girl runs around in circles, giggling as she plays with her black cat. She can't be older than five. Her black hair shines under the moonlight, and her green eyes twinkle. She stops all of a sudden and looks around. Then, she slowly looks up at the moon. It's a full moon. Then her head snaps towards the forest. There's a wolf howling not too far away. In a blink of an eye, she's gone.

In her place is a sleek black wolf. The wolf sniffs around for a bit, but the howling of the wolf brings her attention back to the forest. She breaks into a run towards the forest, howling with them.

She is no animagus. She's a werewolf.