1- Grevane didn't think Harry was a Kemmlerite. he sensed dark/ necro magic trace in Harry. that is it. not once did he call him a Kemmlerite.
He didn't come right out and say it in those words, no. He says "You are, in fact, more of my own persuasion" and "This need not end in bloodshed - particularly not now, so close to the end of the race. Join me against the others." The implication is that he thinks he and Harry have been working at the same goal, Kemmler's teachings, ("the race") and that they should work together against the other Kemmlerites.
2- Cowl did not imply he met Grevane and CT before, he comes out and says it directly in that chapter i provided. he speaks and works with them.
He says he has seen them in action before, and that when it comes down to it, he's the smart one who actually gets things done. That's not the same thing as speaking and working with them.
3- Harry senses the dark magic in Cowl when they meet in front of the bookstore. much like himself. than when Cowl flees he senses a stronger use of the dark magic. also using the Darkhallow is dark magic. why give away yourself using necro magic if you don't need to? it is a tactical decision.
What's tactical about it?
4- Cowl is bonkers. p324 same chapter. H " your the orrect madman for the job."
C, "i do not percieve myself to be mad. but if i were truly mad, would i be able to tell."
He's probably not all there, but he's at least capable of considering the question. Has Harry not wondered the same thing?
5- he considered himself the lesser of the 3 evils. which is a load of bunk since he would be responsible for killing thousands still by finishing the Darkhallow instead of stopping it.
He considered himself different based on what was going happen to the world if Grevane or Corpsetaker ascended versus if he ascended.
6- he spared Harry?! he would have killed him in at the book store. he killed him by breaking the circle holding Erl knowing he would come back to kill him. he told dresden if he came to the ritual he would kill him.
Harry's still alive, isn't he?
He never indicated that he intended to kill Harry at the bookstore. He seemed more interesting in taking the book and testing his strength. He then left when a couple wolves showed up rather than press matters.
He told Harry he would kill him if he got in the way of his plans to save the world from an evil dark god. Harry got in his way twice anyway. He let Harry go after the Erlking summoning, even though he was at his mercy. Yes, he assumed that the Erlking would come back later and finish him off, but he still spared him. He even spared him at the Darkhallow, even when Evil Bob told him the ritual would likely fail with Dresden alive.
7- he wasn't going to wipe out the WCV he was going to place Vitto at its head to run it for him.
Vitto turned on his own people. The Malvoras and Skavis all died, and all the Raiths would have died. The only White Court vampire to survive would have been Vitto, and any lesser vamps who didn't attend. The White Court would have been basically extinct. Nowhere did Cowl or Vitto imply the goal of the operation was to consolidate power under Vitto, and it wouldn't have made very much sense. If that's what they wanted, they should have not involved Dresden and Cowl should have killed the Skavis.
8- why not tell him the WCouncil is corrupt it will make him not trust them and take away an ally from him if he stops working with them. he tells them the WC will fall perhaps tomorrow. Cowl was planning on gaining that power from the Darkhallow so he basically said he was going to destroy the WC.
And why did Cowl need to be so indirect with Harry, who he clearly outclassed? Why did he talk about the horrible things Grevane and Corpsetaker were going to do to the world that he needed to stop?
9- he was burning the Erl book because he did not want the summoning ritual to be used by someone to stop the Darkhallow. since he had already had the book he knew the ritual.
If Cowl was BC, he could have just asked Peabody and they could have never written the book.
in WN Cowl would not have wiped out the WCV. he would have gained contol of them. they were supposed to be involved in the war aiding the RCV. thanks to Dresden backing Lara he took them out of the war. Cowl planned on using Vitto to get them back in the war since the RCV were weakening.
Vitto worked for Cowl and was going to burn a building down and kill dresden and the Ordo. Cowl did not bring Dresden's attention to the culling, Madrigal did it w/out Vitto or Cowl's order.
as for Cowl not killing anyone in DB.... haha. he practically killed Dresden a few times. by breaking the circle he knew the Erl would want to kill him. Harry would have died when Cowl absorbed the Darkhallow as well as Ramirez and thousands of others. only reason he didn't kill Harry was he was worried about Dresden's Death Curse so close to the ritual time.
The only thing Cowl would have gained control of would be the massive pile of WCV corpses he and his agent created.
Lara instigated the Skavis and Malvora plots to kill mortal women, not Cowl. The only direct action Cowl took in White Night was to watch his servant murder nearly all the WCVs. No WCVs would have survived had Dresden not intervened.
Unless Dresden held Erlking in that circle until he died of old age, Dresden had already screwed himself over. Cowl breaking the circle changed nothing with regard to what the Erlking was going to do to Dresden when he got a chance.
Cowl was not afraid of Dresden's death curse, and as Dresden said, he wouldn't need anything near as powerful as his death curse to stop Cowl at the moment he was drawing down the power.
And Cowl's actions in DB were nevertheless very different from the other bad guys, who ran around killing and black magicking indiscriminately. Cowl, meanwhile mugged Dresden, used an EMP, veiled himself, and tried to finish the Darkhallow.