Thank you for the replies. They have gotten me closer to what I'm looking for.
In the ballad "Edward", Edward's mother did not love his father. The evidence for this is that she expresses no sadness when told of her husband's death. She had subtly encouraged Edward to kill his father. The evidence for this is that she expresses no surprise when told of the killing, and also that Edward curses her in response to her question about what he leaves to her.
"Exposition" and "aside" refer, as I understand the terms, to revelations about the back story made "deliberately" by a character within the work. If that is so, then there are no asides and there is no exposition in "Edward". Is there a more general term that would describe asides and exposition and also more subtle evidence of the backstory?
Kent