So the runes on the shack and Lighthouse have come up in the 1k+ post long GS preview chapter thread and DominicJ made a post that really got me thinking... The thoughts are getting a bit research heavy, and experience with my Lash Theory post shows that my posts that cite a lot of WoJ and text read better if they list those quotes at the end, so I'll use that format.
So in the earlier discussion we were talking about how Jim has said that the runes were prehistoric,
woj#1 which strongly implies that they ain't human (being writing, and prehistoric meaning before written history), and DominicJ made this comment:
The Naagloshi came from somewhere, the teach humans the "right" path.
Maybe that lighthouse is the way home, and its noqw barred to him?
So his fellow naagloshi wrote it?
Ok, so this idea meshes pretty well with the description of the origins of the Naagloshii in TC
xrt#1 which even states that they were probably prehistoric. Here's the thing though. It's implied pretty strongly in SmF that what's on the other side from inside the lighthouse is pretty nasty.
xrt#3 However, if you take Harry's description of the Old ones from Dead Beat
xrt#2 about how they were apparently banished from our reality, and ask who dunit, maybe the Holy People participated in it. Also, where did they go themselves? Maybe when they did this banishing, they also left reality themselves (See Jim's description of Benevolent beings
woj#2), and also reside on the other side at the lighthouse (that last bit is a big maybe).
The thing is, The info we have about where the Mordite infused Mistfiend came from,
xrt#4 and WoJ about the "Outside, and mordite"
woj#3 make me think the "Outside" is really just a far reach of the NN, which is also possibly where the "Holy People" left for by choice... I dunno, it all gets a little fuzzy...
I'd like to be able to tie in Jim's comments about how the title of Wardens wasn't originally plurral, and how that seems to be important to the cluebat we got from Eb's journal about "that particular Mantle" but I haven't figured out where it fits with all that...
Below are the WoJ and Text references
WoJ #1Can you tell us more about the runes on the cottage and the lighthouse?
They were not put there by Demonreach; they have been there a very long time. They are pre-Council. They’re a prehistoric script, actually. Harry could have figured out the script if he’d had the comic book.
WoJ #2How do you come up with the bounds between Characters free will and the Divine Hand?
For the Dresden Files, the whole point of The Almighty positive good forces that are out there is that free will is important and they respect that and you've gotta have it and use it. That's the entire point. They are a force of freedom. And it's the bad guys who are going around doing whatever they can to abrogate free will. So for me, where you draw the line is what defines where good stops and evil starts is by how much you're taking away free will and how much you're enabling it.
WoJ #3This posits the question. Besides are reality and nevernever on the other side of the veil, is there anything else? If nevernever is the biggest place, does it encompass all that isn't our world, our reality? I was assume no because I don't think that Mordite (the stuff that the Archive brought to the duel) comes from Nevernever, but from outside everything.
Remember that everything Harry tells you is from Harry's point of view. 
As far as Harry knows, that's the way it is--with the clarification that yes, there is an Outside (where Outsiders originate) and it is a Very Bad Place. The mordite is, quite simply, matter from the Outside.
I'm not saying "that's all there is, there ain't no more." But as far as Harry knows at this point in the books, that's pretty close.
Jim
Text References:Excerpt #1"According to some of the stories of the Navajo, the naagloshii were originally messengers of the Holy People, when they were first teaching humans the Blessing Way."
...
"the original messengers, the naagloshii, were supposed to go with the Holy People when they departed the mortal world. But some of them didn't. They stayed here, and their selfishness correpted the power the Holy People gave them. Viola, Shangnasty."
..."When did this happen"
"Tough to say," Bob said. "The traditional Navajo don't see time the way most mortals do, which makes them arguably smarter than the rest of you onkeys. But it's safe to assume prehistory. Several millennia."
Excerpt #2Outsiders, though, were so rarely spoken of that they were all but a rumor. I wasn't really clear on all the details, but the outsiders had been servants and foot soldiers of the Old Ones, an ancient race of demons or gods who once ruled the mortal world, but how had apparently been cast out and locked away from our reality.
Excerpt #3"Cross into the Nevernever from where you're standing?" Nichodemus asked. "You'd e better off asking the Russian to put a bullet through your head for you. I know what lives on the other side."
Given that they'd chosen this location for the greater circle precisely because it was a source of intense dark energy, I had no trouble believing that it connected to som enasty portions of the Nevernever. There was every chance that Nicodemus was not bluffing.
Excerpt #4The Senior Council managed to contain and banish the mordite-infused mistfiend, a rare and dangerous gaseous being from the far reaches of the Nevernever
