User blog comment:Spritydove/Deeper Thought into the Civil War/@comment-4692902-20120616075537/@comment-5116714-20120619080612

I thought that the whole revering Hagravens started after they were ejected from Markarth. Which is entirely possible. One of the former Harbingers of the Companions delt with the Glenmorril Witches (whom are hagravens) in order to gain greater power. It's entirely possible that the Forsworn formed deals with the Hagravens hoping that they would gain the power to retake their lands. The human sacrifices and briar hearts could simply be results from those deals.