Two of Your Glorious Few (2010)

Mason and Mercy have almost nothing in common except that they are fraternal twin brothers. Mason is simple, ordinary, and good-natured. Mercy is smart, talented, and psychopathic. An introverted musician with an unhealthy revulsion toward "bad" people, Mercy submits to his inner demons and commits a murder. He attempts to quell his rage via creative output in the form of a concept album, but when he's jilted by a young girl he recruited to sing, his bloodlust rises, and so does the body count. Mercy's viciousness against those he deems unworthy to live and his appetite for violence seems to know no limit. Meanwhile, a charismatic man named Denver enters Mason's life with the promise of an inheritance. He reveals Mason's late grandfather to have been the founder of a new denomination based on Christian theology, and Denver, now the leader of this small sect known as The Army of Light, enlists Mason and trains him to defeat a demon named Legion, who they believe will possess someone and lay the groundwork for a biblical apocalypse. When Mason meets the enchanting Grace, one of his grandfather's loyal followers, his attraction seals his fate. He accepts his destiny to slay Legion, even though it means murdering a human host. Mason and Mercy's opposite yet parallel stories are juxtaposed, blurring the lines between hero and villain, religion and morality, fantasy and reality, until the tension escalates to its gruesome climax, and the ties between brothers are pushed to a tragic breaking point.