Abby has always been "sketchy", so that's why I've included her. Other than knowing Liv rescued her from an abusive relationship, not much has been given about her past.
We know she's not above using sex to get what she wants and she doesn't have a problem with breaking & entering or stealing either.
Does it really make sense that it's her . . . probably not, but this show has taken a wicked twist once or twice before.