Supernatural (2005)

S6E11 Appointment in Samarra

In "Appointment in Samarra," Dean approaches Death with the hope of retrieving Sam's soul. Death agrees to assist but demands that Dean take on the role of Death for a single day. Simultaneously, Sam, feeling conflicted, chooses not to reclaim his soul and enlists Balthazar's help for a protective spell to keep it from re-entering his body. Balthazar informs Sam that the spell requires their father's blood. With John Winchester deceased, Sam resolves to use Bobby's blood instead, considering him a suitable substitute.