Mathilda Simmons

Appears in episodes 17 and 18 of the first season. She is one of the young and beautiful nuns working for a heretical cult gathered at an old, unused monastery on the outskirts of Breston. She falls in love with Sebastian at first sight during his infiltration and, after being "marked" by him in a remote cabin, ends up providing information about the cult while smitten. Grell was so displeased with Mathilda, who had been "marked," that he even wrote her name on the list of the deceased, but the marking on her body later proves to be useful when Sebastian needs to escape a crisis.