Let’s think of insulting nicknames for King Korb which Harry will use, I start with Mr Toad.

That's not what we see when Eb is on-screen, and it's not what we see in how other people react to Eb, and it's especially not what we see in Peace Talks.

Every book where Eb is on-screen, we learn that he's not at all who Harry thought he was. In Summer Knight we learn that the irascible hermit is politically connected enough to swing a Senior Council vote. In Blood Rites we learn that the "magic is not for killing" sensei is actually the White Council's dirty-jobs assassin. In Changes we see him ripping the life out of humans, just shredding the first law and everything he's taught Harry.

And Harry's still isolated -- which we're told in the text is "what abusers do". After years of living with Eb, and years of living after that, he doesn't have a single wizard friend until Luccio drags him into the Wardens and he meets Carlos. That made some sense when we thought Eb was a loner hermit, not so much now that we know he's a political mover and shaker with lots of wizard friends.

What are the big fights about in Peace Talks? Eb wants Harry to cut himself off from Maggie -- to whom he says exactly four words, upon first meeting his great-granddaughter, before disengaging from her completely to have a knock-down-drag-out fight with Harry insisting that he has to send her away.

The other is about the White Court Vamps -- but is that really about protecting Harry from them, or about a predator marking his territory? If Eb does use subtle mind-control magic, he might worry that WCVs would be able to spot it in Harry. Could he have been freaking out about Thomas because he thought Thomas could expose him? (Did he arrange Thomas's death for that reason, and to isolate Harry from both the Whampires and the Svartalves?)

And then there's the cornerhounds... we see Eb getting Harry to do two things which are explicitly Warlock-bad things: using a ring of fire and making direct mental contact with the Outside. We only have Eb's word, in a vague and shifty fashion, that the latter is actually safe for Harry. And the former seemed like an unnecessary risk.

And imagine what that scene looks like to a White Council that's thinking about kicking Harry out, again.

Anyway... if we imagine that Ebenezar McCoy was Peabody's boss and has been trying to isolate and mold Harry into his tool, a lot of these things make sense.

However what Eb himself does is represented in the real world by paramilitary police death squads. Murderers above the law. I don't really get the urge to give Harry the Black Staff given that, but whatever.

OK, but what does it suggest to you if it isn't a lazy use of deux ex machina by the author?  Ebenezer's age leading to an onset of dementia could be a natural explanation for his behavior.  Anger issues and sometimes extreme anger can be a part of this illness.  I've personally seen this kind of thing in action and it's a sad and depressing thing to witness.  Perhaps some of the people on this forum have had a similar experience.  More importantly, it fits with the theme of the older members of the Senior Council hanging on because they know a storm is coming and they believe they are the only ones qualified to deal with it, when in fact they may no longer be up for the job.

However, there is another explanation which also fits with a major plot element in the larger story.  Alarm bells should go off when we see a character who is acting against their nature.  It's one of the signs that they are no longer themselves and have been nemfected.

If either of these possibilities are correct then Ebenzer McCoy is no longer fit to wield the Blackstaff.  It's also a clue that Eb is nearing the end of his journey and someone else will have to carry the Blackstaff.  You know, it might not be something that the White Council bestows upon Harry as much it's something Harry picks up when Eb falls in battle.  At that point the Council would have a choice.  They could let the Winter Knight; who is no longer a member of the White Council, use the blackstaff as he sees fit or as Mab sees fit, or return him to his position on the Council, allow him to leave the Wardens; because Harry never wanted to be one in the first place, and become the new Blackstaff of the White Council.  This would also prevent Harry from returning the staff to its original owner.   

Harry was told that being a Starborn gave him power over Outsiders.  What if that was just partially true, but didn't include that he has power over more than just that?  What got me thinking about it was the thread about conjuring Harry is more dangerous for you, than him, and Jim saying that it isn't dangerous for Harry's Name being known as it is for others. 

Another thing is that Harry seemed to defeat Mother Winter in a battle of will's I think?  He doesn't have her absolute raw power, but in a battle of will, I think he won.  Also his battle with Ortega, again a battle of will, and Harry was going to win.  Then when Before was in Harry's mind, Harry won that battle of will as well... 

In much of the dresdenverse, belief is real power.  Perhaps ones will can bend reality as much as the combined belief of lots of people.

Harry's Starborn gift may be an unshakable will that puts him on par with the most powerful Being's out there.  He just needs to tap into it more, like when he faced Before.

As a Nemesis-controlled agent overall Id say. Nemesis invested a metric f*ckton of energy and resources on that scheme, fought the Hunt and even fielded an actual Walker for it.  All it would have take for Nemesis to Win the Day was for Murphy to Not Pull the Trigger at the end.  Or even to simply Miss, as humans do.  I have to think Nemesis would have played that card if it could have.