n.b. "Lasciel's Shadow" and not "Lash."
In another thread, I advanced this theory. I haven't seen anyone suggest it previously... but I could easily have missed it. Apologies if this has previously been thrashed-over!
I thought the notion seemed solid enough to present as its own topic, under its own title. Below, I expand on the idea (a bit of text copied from that thread).
In Battle-Ground, Harry goes ragemode, loses his temper, and tries to kill Rudy. A couple of Knights of the Cross step in... in fact, the ONLY TWO THERE ARE step in!
Let's think back to the last time Harry was called-out for losing his temper: he had to have a chat with the Shadow, for amping-up his rage.
Let's think about Changes for a moment... Harry gets a call from Susan, learns about Maggie, and... begins to feel a "subterranean" rage begin growing. Almost like something in his unconscious was deliberately holding it in check, stoking it, shaping it. "Protect the offspring" says id!Harry... who we know speaks more freely to the Shadow. And at the end of that story, in a burst of "out-of-nowhere" inspiration, Harry comes up with the idea of... sabotaging the woman he (still!) loves, the mother of his child; and sacrificing her to the blood-magic ritual. Seems almost... fiendishly inspired, eh? And then he suffers 2 minutes of amnesia. Gee, whatever could have happened there? Nothing too bad, surely! Those 2 minutes were called a "Chekhov's Gun" and I think it nearly-certain that's right.
Back to Battle Ground, where that Harry-vs-Butters battle scene ended when Butters' Sword stripped off the WK-Mantle... and also revealed the scent of Brimstone. When was the last time Harry's powers smelt of Brimstone? Maybe the Sword also stripped away the Shadow's ability to cloud Harry's senses, hmmm?
Theoretically, Sanya came to Chicago to fight Ethniu, but... that's not the Knights' job! Their job is to oppose the Fallen and to redeem the Fallen's Host. Now the world's entire complement of KotC's are tag-teaming one person... I'm gonna say the odds favor that person being a Denarian.
"But wait" you cry. "Bob already told Harry, after the Raith Deeps, that (a) his head was full of holes & (b) a chunk of his soul was gone." Ergo, Lash really did sacrifice herself, and is gone (producing Bonea, of course).
Yep, I agree! Lash -- the part of the Shadow that Harry "converted" and gave a bit of soul to -- is gone. But as we already know (from seeing Evil Bob, and from Bob's nervousness about Evil-Bob-stuff): these "Spirits of Intellect" can be split in two, with each part remaining a largely-cohisive whole; and furthermore, WoJ has stated that Bonea's genesis was very very much like Bob's; Bob&Bonea are like Bobbsey Twins!
Lasciel... the Temptress, the Deceiver, the Weaver of Webs. I mean... what are the odds she might have laid a deeper deception against Harry? Abandoned one mask, that had failed, and retreated to the deep shadows to try again once Harry had "learned for certain" that the Shadow was gone.
I'm gonna say Jim has given us all the clues we need.