A hand in the face is not what she expected, so without really thinking too much, she backs up just enough to bite down on it. She doesn't even know why, but her sharp fangs pierce skin easily, and while she could probably take a few fingers off easily, the coppery taste of human blood surprising her enough to spit his hand out without doing any major damage. She's tasted blood before, goodness knows she's eaten her fair share of raw whale and seal, but humans just taste different than she expected. Not something she'd like to try again.