Main Theory: The parasite referenced by Demonreach is Lash, who is infected by Nemesis.
For this theory, I’m going to assume that Lash’s conversion to become Harry’s ally in White Night was genuine. The battle against Vittorio and the ghouls was the last definite time that Harry interacted with Lash. Lash took the burden of the psychic assault off of Harry so he could function well enough to take out Vittorio Malvora. From his conversation with Bob, Harry believes that Lash has essentially taken a “psychic bullet” for him, and is permanently removed from his mind. I propose that instead of being killed or removed from Harry’s mind, Lash was infected by Nemesis at this point in the story. From Nemesis’s perspective, Lash is an excellent target to claim because through her, Nemesis has a chance to control Harry: a starborn (whatever that entails), Mab’s go-to agent of constructive chaos, and a man that He Who Walks Behind was already interested in. Overall, Harry is an important piece of Mab’s current strategy, so any influence over Harry is a good thing from Nemesis’s perspective.
From Lea’s behavior in PG and Cat Sith’s behavior in CD, we know that beings infected by Nemesis can resist its control to some degree. Being in the pseudo-angelic category, hence pretty tough, Lash should be able to resist Nemesis in a similar manner. I claim that after Lash was infected in WN, Lash shuts off all contact with Harry in order to protect him from herself. She devotes herself to keeping her Nemesis infection in check. Harry’s parasite induced headaches are the result of Nemesis trying especially hard to take over momentarily and Lash fighting to stay in control. Both headaches noted in CD were points where Nemesis could have secured a big victory over Mab.
- Harry’s headache in the Well occurs as soon as he realizes that he can release the naagloshii and other nightmares with a minimum of effort. If Nemesis can get control of Harry for a few moments, the Well gets opened, and there’s chaos on Earth from all the bad mojo set loose. Nemesis divides Mab’s attention, and wins a big victory. This one isn’t really time dependent, which may explain the increasing number and severity of headaches Harry mentions in the beginning of Skin Game.
- Harry has another headache when he first learns of the Outer Gates in CD. Nemesis is trying to lure Harry away from Mother Summer, and into Outsider clutches, effectively removing the Winter Knight from Mab’s control. Again, Nemesis wins.
Harry’s suicide at the end of Changes is a problem for Lash. Mab and Demonreach need her to run Harry’s body while Harry’s soul is away, but she still wants to keep her no contact policy. If Harry finds out about her, she knows he will try to do something heroic and endanger himself. So she makes a deal. She helps keep Harry alive, but the other two are not allowed to give Harry useful information about her.
Next, we examine Lash as an entity in the DV. Originally, she is the Shadow of the Fallen Angel Lasciel. Basically, she is a less powerful copy of the real Lasciel living in Harry’s brain. Lash is able to grant Harry the use of hellfire, but more importantly, Lash allows Harry to use her knowledge of various subjects. Considering Demonreach’s limited ability to communicate, I believe this is enough to qualify Lash as a spirit of intellect, like Bob. She is the first spirit of intellect that Demonreach associates with Harry, making Bob “ANOTHER ONE.” Furthermore, Lash taking the brunt of the psychic assault is similar to how Bob takes the brunt of the psychic assault from the LotON for Murphy in Changes.
The WoJ on Lash ‘essentially committing suicide with her “free will”’ is usually linked to Harry paying Kincaid to shoot him, but another interpretation is Lash copying Dresden’s choice to become Winter Knight. If Nemesis!Lash is correct, Lash and Harry both sacrificed their free will to a powerful dark entity, and both temporarily committed suicide.
Going from a writing perspective, Jim has stated that the Lash subplot wasn’t in the original story. He added it at the end of writing Death Masks. Since the entire series was mapped out before Storm Front was written, we can speculate that the Lash subplot is replacing something less entertaining. I propose that the original idea was Harry being infected with Nemesis and Harry’s “starborn-ness” was the explanation for how he could resist his own Nemesis infection when others could not. It’s a fine idea, but with Lash as a buffer, things get better. Without Lash, Harry is too special for Nemesis to touch, but with Lash, Harry is the guy that has friends willing to sacrifice to help him. The second version of Harry is a much more interesting character for a reader.
So this is my current Nemesis!Lash theory. Feel free to discuss and poke holes in it.
Relevant WoJ and Text Excerpts
Then a look of almost childish resentment came over her face, and she looked over one shoulder before turning back to me. "I…" She shook her head and said, very softly, wonderingly, "She… doesn't deserve you."
Deserved or not, the fallen angel wasn't getting me. Not ever.
Lasciel squared her shoulders and straightened. "You're right," she said. "It is my choice. Listen to me." She leaned closer, her eyes intent. "Vittorio has been given power. That is how he can do this. He is possessed."
I wished I could have raised my eyebrows. Possessed by what?
"An Outsider," Lasciel said. "I have felt such a presence before. This attack is drawn directly from the mind of the Outsider."
Gosh, that was interesting. Not relevant, but interesting.
"It is relevant," Lasciel said, "because of the circumstances of your birth—because of why you were born, Harry. Your mother found the strength to escape Lord Raith for a reason."
What the hell was she talking about?
Thud-thump: 1:26.
"There was a complex confluence of events, of energies, of circumstances that would have given a child born under them the potential to wield power over Outsiders."
What twist has the series taken that even surprised you? I am constantly surprised by the twists and turns.
The whole Lasciel’s coin plot was something I instigated on the spur of the moment back in book 5, and which isn’t over yet. Lots of things happen that aren’t specifically spelled out, but which can be woven into the overstory plot that I’ve been pursuing. I expect new stuff will continue seeping out of my subconscious and prove to fit pretty smoothly into the outline.
"Well, I told you that the entity in your head was like a recording of the real Lasciel, right?"
"Yeah."
"That recording was written in your brain, in portions you weren't using."
"Right."
"I think that's where the damage is. I mean, I'm looking at you right now, and your head has been riddled with tiny holes, boss."
I blinked and rubbed my fingers over my scalp. "It doesn't feel like that."
"That's because your brain doesn't sense injuries. It manages sensing injuries for the rest of you. But trust me, there's damage. I think it wiped out the entity."
"Wiped out… you mean, like…"
"Killed it," Bob said. "Technically, it was never alive, but it was constructed. It's been deconstructed, and…"
I frowned. "And what?"
"And there's, um, a portion of you missing."
"I'm sure I would have felt that," I said.
"Not your body," Bob said scornfully. "Your life force. Your chi. Your soul."
…
I was quiet for a moment, then said, "And she used it to kill herself."
"Sort of," Bob said. "She chose which areas of your brain were going to take the worst beating. She took a psychic bullet for you. I guess it's almost the same thing as choosing to die."
"No, it isn't," I said quietly. "She didn't choose to die. She chose to be free."
…
It was almost like someone had opened a door in my head, like they were helping me along.
I heard a very, very faint whisper, like an echo of Lash's voice.
Everything I can, dear host.
Q: Will we see Lash or Lasciel again?
A: Lasciel’s story is not over. And keep in mind what’s said about ‘a woman scorned.’ Also keep in mind that Lasciel is NOT Lash; Lasciel did not reabsorb the entity that Harry actually changed. (Yes, he use those words “that Harry actually changed.”)
Lash was apparently able to gain free will from harry, a mortal. Can mortals potentially grant free will to other supernaturals like vampires and faries?”
That’s… a spectacularly complicated question, really.
Lash didn’t gain free will, per se. Lash gained individuality, became a singular entity, self-motivated and distinct from the personality of Lasciel the Fallen. That personality was strongly influenced by Dresden, who believes very strongly in individual choice and responsibility, but doesn’t necessarily equate to free will in the sense of what mortals possess.
You might note that Lash essentially committed suicide with her “free will.” A choice which rather strongly resembles another choice a few books later in the series.
The burning eyes shifted from me to Bob on the table. And then Demoneach did something it had never done before.
It spoke.
Out loud.
Its voice was a rumble of heav rocks scraping together, of summer thunder rolling in from over the horizon. The voice was huge. Not loud. That didn’t do it justice. I just came from everywhere, all at once. The surface of my partly drunk coffee buzzed and vibrated at the all-pervasive sound. “ANOTHER ONE.”
…
The ground didn’t so much tremble at the weight as shift slightly beneath the sheer, overwhelming presence of the ancient spirit. “FOLLOW. BRING THE MEMORY SPIRIT.”
Demonreach growled. In all capital letters.
And the headache vanished.
One second, my scalp was tightening up as two separate ice picks dug into my skull in the same places they always did, and the next the pain was utterly gone. The endorphins my body had started pumping got to the scene to find no pain there and threw a party instead. I didn’t fall over in a dazed stupor, because of my universe-manipulating chops, but it was close.
“Whoa,” I breathed. “Uh…what did you just do?”
“I WARNED IT.”
I blinked several times. “You… warned away my headache?”
“THE CREATURE CAUSING IT. THE PARASITE.”
I stared stupidly for a second, and then sorted through my memories again. That’s right. Right here in this chamber, the last time I’d been here, either Mab or Demonreach had said something about the division of labor keeping my body alive while the rest of me was elsewhere. They’d said that the parasite kept my heart running. I glowered at Demonreach and said, “Tell me about this parasite.”
“I WILL NOT.”
I made an exasperated sound. “Why not?”
“IT BARGAINED.”
“With what?”
“YOUR LIFE, WARDEN.”
I thought about that one for a few seconds. “Wait…You needed its help to save me? And its price was that you don’t tell me about it?”
“INDEED.”
I exhaled slowly and ran my fingers over my head. Something was running around in there, giving me migraines. “Is it a danger to me?”
“IN TIME.”
“What happens if it stays in there?” I asked.
“IT BURSTS FORTH FROM YOUR SKULL.”
“Aglck!” I said. I couldn’t help it. My skin was crawling. I’d seen those Alien movies at a formative age. “How do I get it out?”
Demonreach seemed to consider that for a moment. Then it said, “ASK GRASSHOPPER.”
I peered a little closer and felt a sudden, horrible pressure inside my head. I felt dizzy for a second, nauseated, and at the same time part of me was screaming that I needed to ditch my escort and go look at these things for myself, that there was something there, something I wanted to see, something I wanted to stare at for a while. A cold, somehow greasy tendril of energy slithered around inside my head, something I had felt before when…
”You heard me, Mittens. Get me a freaking Coke and do it now.”
Sith remained in place, as if locked to the floor, though his whole body was quivering, his claws sheathing and unsheathing in rhythm. But he didn’t fly at me, ripping and tearing, either.
“You see,” I said, “Cat Sith is a creature of Faerie, and he swore an oath to Queen Mab to obey her commands. She commanded him to obey mine. And I just gave you a command, kitty. Did Mab release you from her command? Did she suspend the duties of her vassal?”
Sith snarled again, his eyes getting wider and rounder, his tail thrashing around wildly.
…
“Fight it, Sith,” I urged him quietly. “It doesn’t have to win. Fight it.”
For a second, I thought I saw something of Cat Sith’s smug, contemptuous selfassurance on the malk’s face. And then it was gone. Just gone.
“Then give me the sword and I’ll do it myself. I’m not leaving her.”
Lea made a sudden choking sound.
I frowned at her. Her eyes bugged out and her face contorted with apparent pain. Her mouth moved, lush lips writhing, twisting. A bestial grunt jerked out of her throat every second or two. The fingers of her freed hand arched into a claw. Then she suddenly sagged, and when she turned her eyes back to me, they were my godmother’s again; one part lust, one part cool, feline indifference, one part merciless predator.
“Child,” she said. Her voice was weak. “You must not free me.”
I stared at her, feeling confused. “Why?”
She gritted her teeth and said, “I cannot yet be trusted. It is not time. I would not be able to fulfill my promise to your mother, should you free me now. You must leave.”
“Trusted?” I asked.
“No time,” she said, voice strained again. “I cannot long keep it from taking hold of…” She shuddered and lowered her head. She lifted her face to me a few seconds later, and the madness had returned to her eyes. “Wait,” she rasped. “I have reconsidered. Free me.”
I traded a look with Thomas, and we both took a cautious step backward.
Lea’s face twisted up with rage and she let out a howl that shook icicles from their positions. “Release me!”
“What the hell is going on here?” Thomas asked me.
“Uh,” I told him. “I’ll get back to you after we get out of Dodge.”
Is Lasciel going to make a comeback? The coin is still buried in the lab, right?
Her coin isn’t in the lab anymore. Her story is not yet over. However, both Lasciel and Lash appeared in Ghost Story, but not under those names.
Edit: Forgot to add in the WoJ on both Lash and Lasciel appearing in GS.