1) Legal terminology 2) One who narrates 3) Storyteller, essentially 4) Vocal duet 1) Storyteller 
[Pete Yorn and Scarlett Johansson song] ...[law] Relator ər, female relatrix s, (Latin for `narrator`) is the legal term meaning a private person at whose relation or on whose behalf an application for a quo warranto or mandamus is filed. The relator appears as one beneficially interested, but the action is maintained on his behalf. The relator furnishes the knowledge or facts on w...
• (n.) A private person at whose relation, or in whose behalf, the attorney-general allows an information in the nature of a quo warranto to be filed. • (n.) One who relates; a relater.
Re·lat'or noun [ Latin : confer French relateur . See Relate .] 1. One who relates; a relater. 'The several relators of this history.' Fuller. 2. (Law) A private person at whose relation, or in whose behalf, the attorney-general allows an informatio...