It is possible that Margaret LeFay was a previous holder of Lasciel's coin.
  It would explain why she thought she could get away with antagonizing so many powerful entities.  It would explain her ability with many different types of magic.  Lasciel could have tutored her on types of magic most wizards knew nothing about.  It would put her going to the dark side, perhaps being a founder of the Black Council, into an understandable framework.
  There are some problems with this idea though.
  First, Margaret and Lasciel should have been able to resist Lord Raith.  He would not have been able to even partially enthrall her if Lasciel was helping her.
  But the big problem is that neither Nicodemus nor Lasciel ever mentioned to Harry that Margaret was a holder of Lasciel's coin.  Why would they not tell Harry that?  It might have been enough to get him to try it.

APG

  The issue as described by Bob in Dead Beat is, yes Harry ordered Bob to forget what he knew from his years with Kemmler.  However, when Cowl had possession, he could reverse that order.
  So, after the events in Dead Beat Bob undertook to get rid of that knowledge permanently.  He did this be splitting off Evil Bob.  He did not seem to recall doing this, but it must have happened shortly after the end of Dead Beat.

APG

  I still vote for Evil Bob!!!

APG

  In Blood Rites Lord Raith tells Harry he heard the conversation between Harry and Thomas in the portrait room.
  He did not know Harry was Thomas' brother before that.  So, I don't think he realized Harry is the son of Margaret LeFay.  Many do know that, but it is a detail Lord Raith might have missed.

APG

  Someone suggested in an old thread that perhaps Shagnasty was the skinwalker that  Morgan nuked.  He survived it, and over time was able to reform.  However, it would provide a strong reason for him to be pissed off at Morgan.
  It was also suggested that Shagnasty's attack on Raith manor was to help Madelaine escape.  That is, she heard about Harry and Luccio visiting, and made a phone call asking for help.

APG

  The assessment is that Peabody would have known about Luccio's boot camp, but nobody thought to include him in the list of possible traitors.
  As secretary, he would have known almost everything the Senior Council  knows.  The locations of safe houses and camps would have been in the orders and other forms he would have had the Senior Council sign.
  In addition, renting or purchasing the land for the camps, and the order to deliver supplies and equipment would have gone through him.

APG

Ref:  http://www.jimbutcheronline.com/bb/index.php/topic,48685.msg2258158.html#msg2258158

  The above link refers to a post I made a while ago about Justin, Elaine and Harry.
  I suspect that like Margaret LeFay, there is something important that we don't yet know about Elaine.
  My idea was that Harry called Elaine almost as strong as he is.  Harry is in the top 50 to 100 wizards worldwide for his age group.  So, I don't think it is possible Justin DuMorne could have found two apprentices that powerful by chance.
  We know from Blood Rites that Justin was an associate of Margaret LeFay.  I suspect Margaret and Justin worked together to learn how to create a Starborn.  After Margaret fled from Lord Raith Justin used that knowledge with Elaine's parents to create a second potential Starborn.
  This theory explains why Justin was aware of both Harry and Elaine.  It also suggest Justin may have been the reason both Harry and Elaine became orphans.

APG