Being part Shifter, Tessa can alter her appearance to mimic any other person, animal, plant or object. She uses the ability more often than her father or brother do. However, her favoured appearance has long, wavy dark brown hair, a pale complexion and the occasional scattering of freckles. She is slim and is 5'8 in height. Her blue eyes are lighter in shade than her mother's and sometimes can look grey.