Haven't we met them as his personal assistants outside his office?

Maeve's protection was predicated on the idea that no other person in that circle had been prepped to make her a target for the mantle once Sarissa had the Summer mantle.  Murphy wasn't and Justine could not have been.  Sarissa's training with Harry by Mab and Molly's by Lea are almost exactly the same.  The military calls that lighting the target. But you are correct in that this foreshadows Justine haven been taken.

As readers we should have suspected when Justine became Lara's assistant. Prior to that she wasn't exactly tied real tight.

I don't think her becoming assistant was too suspicious, but the stability without Thomas feeding from her too calm her should have been.

Assuming I'm remembering the timeline correctly.

She was being fed on up until Thomas held back in Blood Rites. Then she had true love protection, which makes her ideal as an assistant for Lara, as she's untouchable to internal manipulation. But yeah, the mental clarity should have rung bells. It's just hard to know if that was due to character growth, plot necessity, or specific cause.

And I still say she was infected by Lord Raith. 

I've mentioned before that I think Mac is the transubstantiated form of the archangel Raphael, and that he gave his Grace to Merlin in order to build Demonreach similar to how Raphael made Dudael as an earthly prison for Azazel, and that Alfred is a construct -- or "vessel", as he calls himself -- to hold the Grace.

That's a quick summary, but I'm sure the posts are somewhere.

Anywho, I just posted elsewhere that Maeve seemed to know Justine was infected in Cold Days. She even said in her victory speech that if she died, the mantle would go to a "hapless mortal" (Molly) or "an instrument of some foe of [Mab's]" (Justine).

The whole reason Justine was there was to act as insurance to keep Maeve alive or keep the Lady mantle out of the rotation.

Since Justine was there for a specific reason, it stands that Mac was too. They weren't just kidnapped earlier and then brought along for no reason.

I posit that Mac was there because of his relationship with the island prison. I think part of the gambit was to put Mac in jeopardy, in hopes that the island would act to save him, or he'd take the Grace back to save himself, or his death would weaken the defenses.

COLD DAYS

     “Oh, oh!” Maeve said, her body twisting into a
spontaneous little dance of pure glee. “You never
saw that coming, did you, Mother? It never even
occurred to you, did it?” Her own eyes widened in
lunatic intensity. “And how will you slay me now?
Whither would my mantle go? Where is the nearest
vessel now? Some hapless mortal, perhaps,
ignorant of its true nature? The instrument of
some foe of yours, in alliance with me, ready to
steal away the mantle and leave you vulnerable?”
Maeve giggled. “I can play chess too, Mother.
Better now than ever you could. And I am now less
a liability to you alive than dead.”

I'm sure someone else caught this, but I only realized it just now.

Maeve names the two options for who gets the mantle if she's killed.

A clueless mortal, or a tool of Mab's nemesis.

Molly, or Justine.

My original thought was that she was referring to Molly and one of the handmaidens/court members in the raiding party. Someone allied with her on the hill. But she was talking about Justine and Nemesis.

I wanted to think Justine was possessed by Nemesis later, but Maeve flat out says that if she's killed, the mantle will 50/50 go to Nemesis.

I just took Harry's flawed narration as fact. He thought Maeve hadn't thought it through. But she had. Her gambit played out exactly like she thought.

I expect the ending will be a bit more optimistic than that.

I think the end will be a new world a lot like this one, but with magic openly practiced and the supernatural public knowledge. Where Harry won't be the only wizard in the book.

I expect society to collapse, and then a period of darkness (a post-apocalyptic world) and then maybe, a renewed world. But probably not much like our world. Assuming the second coming or some such doesn't happen and everyone goes to Paradise.

I think things will break at the end of the case files, be very bad and apocalyptic during the big apocalyptic trilogy (it's in the name, so), and then just starting to rebuild at the end in the epilogue.

I'm also currently intrigued with the idea that, with numerous starborn running around, one other than Harry might play the big role that decides things at the end of the case files. He might be the starborn that rights the ship, but another might sink it to actually cause the BAT.

It all depends on how it was done, I think.

Jim said that when Athena popped out of Zeus' head, he created a body for her to be in. Harry couldn't do that for Bonnea in the same way so they had to use Bob's back-up skull.

So did Drakul create a body, or possess one, or is it the combination of a starborn ascending and that being taking shape? The answer is very important I think.

You're onto something with the ectoplasm versus real body. I believe that's part of how beings like Vadderung and Drakul can affect the universe in a big way, that non-mortals can't. I don't know if they get free will when going mortal...but I wouldn't be surprised if their will becomes "freer". I also suspect it require less energy from them to maintain a mortal body than an ectoplasm one and it can't be cut-off or banished as easily as an ectoplasm body. Uriel, Ethniu and others don't use ectoplasm bodies though, so it does make you wonder if their bodies are those spirit+flesh bodies mentioned and never talked about again in Fool Moon. If so, why doesn't Drakul do that?

Seem it could be he was looking for protection from the other powers by hiding in a mortal body. But I think it's more likely it offers an advantage that an immortal body doesn't. Mab hinted this when she told Dresden immortality is no substitute for intelligence. Ethniu hints at this when she muses why Vadderung is so mortal now...and suggests it's because he thinks he is deep in the "game".
All good, it was fairly recent information.

Yes, I think that's the salient point. Has Drakul been body-hopping or did he get stuck early on in human history, maybe in his first body, and holding various personas over time in the one body? I think there isn't enough information as yet to make a clear decision. There is merit in both ideas. My gut feeling is that he got trapped in his original starborn body back in the day - somehow that just feels right. Which makes it all the more impressive he is still running around. 

Black Court simply struck me as the original condition and other vampires were simply other variants. But I am less leaning to Drakul being the sole creator of all the vampires and rather just the father of the Black Court. While there are connections, he doesn't display obvious Red Court and White Court tendencies or characteristics (excluding the Willpower attack - but I think that's another thing...). I do think though that he offered a worthy opponent a long time ago what Drakul described as "the dark gift of immortality" in exchange for servitude. That's how he started the Black Court, I think.

Yeah, I don't think he's Luci. It would both be too obvious and not make sense for all the reasons you stated and more. The Demon Lord theory now seems the most likely.

The Apocalypse reference is a good one. It makes a fair bit of sense. I can see Vadderung as a Prof X type and perhaps Nicodemus or Marcone as a Magneto type, working together to defeat him. Certainly a vibe.

It would be good to try and make a list of candidates for possible personas that Drakul has held. I will think on it.

Now that his age is indefinite, it's all but impossible to pin down any facts.

I like the idea of the strix being a Greek-gods cursed human family that resulted in blood-drinking bird creatures, and for some reason a branch helped found the strigoi, like the magical equivalent of evolution. Then later, Drakul experimented to make a new breed that is the Blamp.

I think that would allow for different courts to evolve from their own regions and origins around the globe. Since blood drinking was fairly common back in the day, I could easily see each having a similar but different path.

Blood sacrifice to gods could have started it all over the place, or familial curses, or demonic possession... So many options, so little guidance.

I'm leaning towards the historical ties between Greece and Romania, and the Wallachia region.

• We know Romanian strigoi have a root to the greek strix, which were nocturnal birds that scream and drink blood and hang upside down like bats and could be deterred with garlic.
  
• We know Keres, dark winged female/bird hybrids that were the Greek shepherds of souls that died violent deaths. The Keres were sisters to Thanatos, the Greek god of the peaceful death.
  
• There were Greek rituals, often associated with blood drinking, with Hecate.
  
• We know Hades and the Greeks had Cerberus and other hellhounds that guard hell to prevent spirits from escaping.
  
• We know Thanatos was a lesser death god, who for a time was said to shepherd souls, but was later replaced by Hermes.
  
• Thanatos was said to not like humans or the other gods.
  
• Thanatos was the child of Nyx (Night) and Erebus (Darkness).
  
• We know Drakul created the Black Court, either from scratch or from other species like strigoi and strix.
  
• The Blamps are said to have the full Stoker power set, including being nocturnal, shape shifting, and magics.
  
• We know the Black Court likes to use darkhounds, dogs that have the same dark power of the Blamps.
  
• We know Drakul had a servant for centuries named Hellhound.
  

I'm going to form a loose WAG that Drakul might be Thanatos.

• Let's say an ancient Greek performed a blood ritual for Thanatos, either to stave off death or worship it.
• Either by design or by accident, Thanatos ended up possessing the sacrificer or the sacrifice.
• Thanatos lived in that form for centuries, the embodiment of the undead.
• Over time he made Blamps (and who knows, maybe strix and strigoi as well) in the image of the Keres.
• He made darkhounds in the image of Cerberus and the other hellhounds.
• He sired or found a half-breed (Kincaid) to act as his personal watchdog/Cerberus.
• Kincaid's appearance under Harry's Sight was demonic, but more importantly it was superimposed by the "corpse-spector of death himself". Possibly Mavra hiding behind a veil as we've theorized previously, or possibly an imprint on Kincaid from his time with Drakul, "Death himself".
  
• He doesn't like humans or the other gods, and has motivations against both. Maybe he wants empty night because that's his mom and he has mommy issues. Maybe he wants to remake reality as a limbo between life and death, which he would rule alone. Or maybe he's got no great plan.
  

EDIT: I corrected Thanatos' parentage and added the bit about Kincaid's appearance.

Proposals for satisfactorily resolving the conflicting information that has been presented about Drakul and Dracula.

Please share any additional information I may have forgotten, and we can try to address any concerns.

1) Drakul is a starborn, and also a half-breed (source:Eb), and also something pureblood trapped in human form.
Proposal: Vlad II was a human starborn. One way or another, he was possessed by an immortal being or mantle, which fundamentally changed him into Drakul. He is not truly a half-breed, but is still a combination of human and creature.

2) Dracula joined the Black Court as an act of teenage rebellion, and also founded the Black Court.
Proposal: Vlad III was the son of whatever Vlad II had become, making him a half-breed that hadn't chosen. The strogoi, Romanian vampires, had already existed for millennia, and some were serving Drakul. They did not have an organized structure until Vlad III became one and formed the Black Court, making them into an organization.