Dr. Deern is a middle aged man with graying black hair, a trimmed grey beard and rounded spectacles. He wears a white undershirt with a green tie, a brown suit and trousers, as well as a pair of black dress-shoes.
Throughout the entire game, he is the only member of the Oswald Asylum that shows any form of sympathy or compassion to Fran Bow. When she first collapses after taking her first pill of Duotine, he is instantly alarmed and tells the nurse to never let her take it again.
After he is fired, he wants to find out more information about what was actually going on in the asylum. While on his way to question Fran's Aunt Grace, he is surprised to find Fran still alive. Dr. Deern then takes her with him in search of answers.
His ultrareality self implies that his father was abusive, saying "...I tried to tell my mother the truth, but father would harm her as well. I don't want my father playing with his knife again... My arms hurt..."
His subsequent reaction to Fran asking about his father seems to confirm this.
Dr. Deern’s hair style, beard, round eyeglasses, and manner of dress (including his hat worn in Chapter Four) is reminiscent of Sigmund Freud, the founder of the field of psychoanalysis.