Christopher was the deceased younger brother of Derrick, the patient in the Season 8 episode Holding On. He was only seen in photographs and was portrayed by actor Brayden Brooks.
The team finds a photograph of Christopher when doing an environmental scan of Derrick's apartment. They confront him about it and he admits it is his deceased brother. He later admits he is hearing voices that he believes come from Christopher.
Jessica Adams comes to believe that Derrick was never allowed to properly grieve for Christopher and that this is the primary cause of his symptoms.