Theresa 'Tessa' Grey

Tessa is the heroine of the novel. Tessa was born and raised in New York. After her mother's death, she came to London to live with her brother Neal. When Tessa arrived, she was met by a woman she did not know and forced to do things she did not realize she could do. It turns out that Tessa is the child of a demon and a Shadowhunter, a new breed of person that makes it possible for her to take on the shape of a person or creature whose essence she is able to touch in an object. Mortmain, the Magister, knows of this power because he was the one who arranged for Tessa's conception. As a result, Mortmain plans to use Tessa as a weapon against the Shadowhunters, whom he despises because they killed his adoptive parents who were a warlock and a witch...