One thing to consider is that Justine/Nemesis has a wizard ally capable of summoning Outsiders....  Listen could be that person.  He's a Starborn....  Perhaps that's why he betrayed Ethniu, because he's an agent of Nemesis.  Morgan was worried that Harry, as a Starborn was an "agent of Nemesis".

Listen is more likely than Justine, but I still don't like him for it.  You don't insert creatures famously associated with time travel into a story without there being time travel involved.

As a side note, starborn isn't a subcategory of wizard, is it?  We've never seen Listen throw around any magic.

It isn't random for starters.  I reread the whole section over again, to begin with Harry's "Spidy Star Born" sense perked up when Justine reacted "rationally" not "emotionally" to the news about Thomas.  "Does Lara know?" Not, "Oh my God is Thomas okay?"  Or anything like that.. At that point he had nothing to go on, just that her reaction seemed off.. Then in the next chapter when the Cornerhounds are actually called up, Harry states that only a mortal can call an Outsider up.  So guess who? Justine.  Justine wasn't rid of Harry, he had left her apartment, but she was still very much on his mind, if for no other reason than to protect her, that is why he hired Mr Grey.  Justine knew she'd remain on Harry's mind, no,no, she wasn't rid of him... But she did try to get rid of him via the Cornerhounds.

What isn't random?  Who said random? 

Justine reacted rationally first, then broke down.  It's a little weird (but I don't think totally abnormal in reality), and it pings in Harry's mind as smart and that he had underestimated her.  Then he leaves to do his investigation around her building.  At that point, Justine has some breathing room; she's rid of Harry for a few hours.  If Justine does nothing (and Eb hadn't shown up), Harry doesn't find anything and goes to talk to Lara instead of getting patched up by Butters then talking to Lara.  Nothing significant changes in the plot if Nemesis doesn't make a move there compared to summoning cornerhounds.  That's my point in that it doesn't fit Nem!Justine's motivations well.

The answer to your second question is no, Nemesis can't just go around "forcing mortals" to call Outsiders up here, there, and everywhere.... It doesn't work that way, there has to be cooperation and a motive for a mortal to do it..  The mortal might be playing with the occult like Madge was, then Lord Raith tempted her further.  The one that doesn't fit is Maeve, since she wasn't a mortal, but I suppose Cowl and Kumori counts as mortal and presenting Lea with the infected Knife was as good as calling up an Outsider since it was a Nemesis delivery system.  Which should also answer your question about why there was no summons on mass, stealth was needed to pull it off.. Thus Maeve was too far gone before Mab found out and managed to gain the island before it's defenses were fully employed.

So if you think Nemesis needs cooperation and motive for a mortal to summon outsiders, and you think Justine summoned the cornerhounds, you're saying that Justine is willingly cooperating with Nemesis against Harry?  I don't buy that at all.

I don't think Nemesis can force mortals to summon outsiders either, including Justine.  If it could, the cloak and dagger strategy of getting hooks into the various supernatural nations it uses is needlessly complicated.  It could just use mortals to quietly summon an army of outsiders through the Outer Gates then take over directly.

I understand the significance of the Hounds.  The point is who is traveling and why. You suggested Eb.  But it's the same as Nemfections.  If everybody is nemfected then sooner or later the story falls apart in contradictions. My thinking is if time travel is involved then the traveler will always be Harry in some form or the other. But which form?

In this case having Justine summoning or causing to be summoned, the Hounds, then why?  Jim has had multiple Outsiders on the page at least once in Cold Days, right? But why the Hounds specifically? The same for Eb.

I suggested future!Harry was being chased in the time travel book, not Eb.  He used his past self to give himself breathing room in that book.  We just won't find out about the details for a few books. 

In PT the cornerhounds served as a way to delay Eb and Harry having their final confrontation, as a way to tease out starborn information, and as a mid-book action scene to ramp up tension.  For the plot though, the cornerhound attack doesn't really fit any character's motivations well.

Oh I missed that!  Ok I'm really leaning towards Griff's theory.  Especially since Maeve said it was ironic that Mac would die on the Island (where in theory his grace is being used to power it).  Another possibility could be that the Angels watched the Outer Gates and also set up the Demon Reach prison.  They then handed over responsibility to mortal kind.  Mac could have been the angelic Warden of the place.

That could also be true.  I was reading about the Gates of Heaven (I think there are 3).  Perhaps one of them leads to the Outside and it was Mac who as an Angel watched the Outer Gates.

I think it's also interesting that Mab calls Raphael the Demon Binder (I think it was in SmF?).  There are alternative explanations, but if you're gonna call something a demon binder in the DV, somebody giving the juice for Demonreach is probably a good fit for the nickname.

I think he was the original Gate Keeper.

@groinkick

Quote

“You!” Sharkface snarled. “You have no place in this, watcher. Do you think this gesture has meaning? It is every bit as empty as you. You chose your road long ago. Have the grace to lie down and die beside it.”

Butcher, Jim. Cold Days (The Dresden Files, Book 14) (p. 229). Penguin Publishing Group. Kindle Edition.

I mean, Sharkface literally calls Mac empty and talks about grace in that line.  Pretty strong evidence of an angelic vessel that's given away Grace for a purpose.   

Why does there have to be?  Nemesis infects with a strategy in mind, who it sends knows this.  HWWB is a good soldier, I doubt he'd go rouge and allow his mortal host to summon up Cornerhounds "just because.."  Also note that their mission appeared to be specific, get Harry and along with him Eb if they could.. When they failed they went back to where ever.  Justine called them up for a purpose, to distract and stop Harry..  Harry even says it would take a mortal in the area to call them up if I remember correctly.  If I did remember that correctly, that was a neon sign, screaming, "CLUE!"  It's Justine.  Unless it was the doorman, that is still possible.

The goal of the Outsiders is to end reality, and the Outer Gates defend reality.  Only mortals can summon Outsiders (so they get a free pass to skip the Gates).  In the situation where Nemesis can use a mortal host to summon outsiders, why not use that and go around reality's defenses to further the goal of destroying reality? 

I mean, it would make sense from the narrow perspective of PT for Justine to have summoned cornerhounds (sweeping any questions of magical ability for that under the rug for now), but in the wider world of Dresden, it doesn't fit what we're told about the nature of the Outer Gates.

the spies do not have to be Svaltalves. Did Harry have a spy in the White Court? Sure he did - Justine. The White Court didn't find her. She left when it was clear she was Nemfected.  The Black Council had their agent in the White Council - LaFortier (plus others).  Cowl had his agent in the White Court - Vitto Malvora. As for what happened on Demonreach - doesn't Lara have an organization? Vadderrung does - Monoc Securities. We know Lara employs humans - security, medical, Justine... Vadderung may as well. Reports get filed, and files get leaked. People who get secrets sell secrets. Money is power, and power corrupts.

Look at real life - Julius and Ethel Rosenberg were not Russians, were not present at atomic tests, and were Russian spies passing atomic secrets.

Idk, the svartalves don't seem the type to place spies.  They're very by-the-book.

Regardless, there were 4.5 people present near Demonreach at the end of PT.  Harry, Lara, Justine, Murphy, and technically Thomas.  Which one of them is gonna talk about what happened there?  Not Harry, not Lara, and definitely not Murphy.  It would all depend on Freydis, and if anyone she'd tell Vadderung.  I don't think he'd tell either.  The events on the island will stay secret.