In the Dresden's backstory, when he's a child, Justine DuMorne, widely-respected warden of the White Council is an abusive foster parent and teacher who tries to isolate Harry and then put the mind-whammy on him to make him into a starborn thug under DuMorne's control.
That goes wrong when Harry (inexplicably) kills DuMorne and is arrested by the White Council for murder.
Harry's version of events is that Eb is a saintly old man who risks his life to spare Harry, takes him into his home and teaches him the good parts of magic and self-control and makes him the man he is today.
And yet...
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.