Steven is a fair-skinned man of average height with blond hair styled in a bowl cut. He has blue eyes. Despite being Melissa's twin, he does not look similar to her, except for a slight resemblance. He generally wears a lab coat over his normal clothes.
Steven is a mostly quiet person, burying himself in his work often. He can be very protective, especially over his sister, Melissa. He tends to be very passionate about his projects and research.
Born due to an affair between a human man and an angel woman, Steven was raised by his father and step-mother, unaware of his angelic heritage. At an early age in his life, his parents died and he was sent to live, along with his sister Melissa, with his uncle Richard Devlin.
Having excelled in school and developed an interest in Richard's lab work, Steven was hired at the Laboratory of the Unexplainable and soon became an assistant scientist. His regular studies include angels, demons, and their origins.
- He has a fondness for soup.