Hermes Costello is a tall, muscular, afro-latina woman with tan skin and striking yellow eyes, as well as a charismatic, vulgar disposition and no-tolerance policy. Her hair is long, curly, and black. Usually styled in long box-braids.

Her fashion sense is eccentric and punk-rock, with a penchant for greens, yellows, and black shades. She is determined and loyal, especially to her loved ones. She misses her older sister who raised her, Gloria, after she was murdered. 