Mac's True Nature (spoilers for BG)

[Dina]

I don't really understand that Mac was supposed to ask for help. I see it more banal, if he fells the bar fells.

That's not my interpretation of the scene. My interpretation is that the plaque paints a target on the person who's blood is on it. The protection offered by the plaque is connected to Mac, so any attack would come at him. 

That's a huge difference from helping defend. If the plaque had been present in the Cold Days attack, then rather than Before breaking the threshold of the place and attacking all three there, he would have had to have gone through Mac and killed him.

It's putting a huge, inescapable target on his back.  It makes a huge difference in regards to strategy.  It makes him the Tank. And if he isn't strong enough, he'll wind up dead.

And as for his reaction, his unease wasn't just putting his blood on it, if it was that at all. It was that Harry had deduced what he was. 

What do you mean? That any attack will be redirected to him or that the attackers would actively search for him? Because I think it's the latter (and in fact, some attackers may not know how the protection is working). And then, Mac may be clever in choosing to hide (or better, blur in the background) better than actively tanking.
Also, I disagree with your interpretation about his unease. He specifically sighted before smearing his blood. I don't know exactly why. Perhaps it is because, as Mira says, he was choosing a side. Or perhaps is because he had too much devotion for the placard, perhaps he didn't feel worthy of doing that. I am not sure.
And I still don't know who told Harry all that about the pieces but I want to know what all of them (including the Grial) do in the Dresdenverse.

[Mira]

And I still don't know who told Harry all that about the pieces but I want to know what all of them (including the Grial) do in the Dresdenverse.

Yeah, that remains a mystery, it could be that Alfred knows just what the artifacts can do. 

[Feral Plum]

Such angels taught men. Wanna bet Mac taught brewing? I am convinced he is also Ethniu's ex, the father of Lug(h), the Celtic sun god. Such blood lines are known for giantism. You mentioned Goliath.

Watchers watch something. And they must report. I think of Mac as a spy or an investigator. He showed up in Chicago just before Harry.
If Mac is investigating, his appearance may be unrelated to Dresden, and related to the appearance of Nemesis and the odd occurrences which started the Dresden Files when they did and not before.
If he is watching, well, there is something that brought him there. 6'9" isn't unheard of, but it is odd for someone who's grandfather is 5'8" and who's father is not described as tall. Maggie Le Fey is 6' even. 5'10'' is the 99th percentile for women by my charts. [Butcher knows these charts: Ivy referred the her height percentile for her age.] I wonder if giantism run's in Harry's family, either from Ebenezer's wife or Malcolm's side. If Mac as a 'tripped' angel lusted after women, he may have a very personal reason for watching Dresden.

[Telynn]

I took it to mean that the bar has super protection, everyone in it will be safe, as long as Mac is alive.  Which puts a huge target on his back.  I didn't really take it to mean Mac himself will be forced to become super fighter to protect others.  But he will be put in a position to fight to save his own life, if someone wants someone else in the bar dead.

[Bad Alias]

I thought the one about Lasciel's offense was more trying to convince both sides she was loyal to them and play them against each other for her own ends, not just honestly standing aside.

It could have been, and, yes, that's not just standing aside.

[Griffyn612]

I don't really understand that Mac was supposed to ask for help. I see it more banal, if he fells the bar fells.
What do you mean? That any attack will be redirected to him or that the attackers would actively search for him? Because I think it's the latter (and in fact, some attackers may not know how the protection is working). And then, Mac may be clever in choosing to hide (or better, blur in the background) better than actively tanking.
Also, I disagree with your interpretation about his unease. He specifically sighted before smearing his blood. I don't know exactly why. Perhaps it is because, as Mira says, he was choosing a side. Or perhaps is because he had too much devotion for the placard, perhaps he didn't feel worthy of doing that. I am not sure.
And I still don't know who told Harry all that about the pieces but I want to know what all of them (including the Grial) do in the Dresdenverse.

I guess we're just interpreting it differently, like Mira said.  I don't know, I took it as the placard would put up a barrier to keep things out that were attacking.  It's not powered by Mac, just as the other vault items don't seem to be powered by the wielder. 

But Harry clearly states that it'll be dependent on Mac, that it "focuses energy on an individual", and that "Anything that wants to get to them will have to go through Mac first".

To me that sounds like it's creating a threshold that links to Mac.  So either he dies if it falls, or the energy is directed at him, as described by Harry. Either way it's a lot.

But as for his consternation, to me it's clear that he's not nervous about the blood on the placard, but instead is nervous about Harry figuring out what he is.  Harry even thinks "it was pretty clear that he didn’t like that I’d realized what he knew."

Not that he was nervous about the placard or choosing sides or risking himself, but just Harry knowing that he was more than human.

[Bad Alias]

To me that sounds like it's creating a threshold that links to Mac.  So either he dies if it falls, or the energy is directed at him, as described by Harry. Either way it's a lot.

That's where I'm at.

[Dina]

To me that sounds like it's creating a threshold that links to Mac.  So either he dies if it falls, or the energy is directed at him, as described by Harry. Either way it's a lot.

But as for his consternation, to me it's clear that he's not nervous about the blood on the placard, but instead is nervous about Harry figuring out what he is.  Harry even thinks "it was pretty clear that he didn’t like that I’d realized what he knew."

Not that he was nervous about the placard or choosing sides or risking himself, but just Harry knowing that he was more than human.

About the placard, my opinion: Yes, it creates a megathreshold. So, if a human just wants to kill Gary, he enters without problems and kills him (assuming no patron stopped him or her first), but King Cobb couldn't put a step in, or throw a fireball to the bar that damages anything inside. Now, if the first human goes for Mac instead of Gary and succeed (difficult as it may be), the threshold will become super weak (thresholds in taverns and bars are weak, before for their nature they are open to anyone that wants to enter) and every wizard, vampire, whatever, would enter with little troubles. So, if King Cobb wanted to kill Gary AND HE COULD SENSE THE KIND OF PROTECTION THE BAR HAS, he could send a human mercenary for Mac first. If no, he had no particular reason to go against Mac.

About the consternation. Yes, at first he was troubled about Harry knowing who (or what) he was (and perhaps about Harry having something like that). But after that, and when the first thing was already revealed as inevitable, he still seem disturbed about actually using the placard himself.

[Mira]

But as for his consternation, to me it's clear that he's not nervous about the blood on the placard, but instead is nervous about Harry figuring out what he is.  Harry even thinks "it was pretty clear that he didn’t like that I’d realized what he knew."

Not that he was nervous about the placard or choosing sides or risking himself, but just Harry knowing that he was more than human.

No, lets go through this again..

1]  Harry and Murphy enter the bar,Harry has his backpack with him.

"Mac," I said clearly. "Storage room.  We need to talk."
Mac was a lean man around six feet tall with broad-knuckled hands and
a shinning bald pate,dressed in his usual black slacks, button-down shirt,
and spotless white apron.  He'd been a friend for a long time. He looked at
me and then nodded toward his pantry and office.

No fear, no worry, he knows what is going on in the city and how scared people are and that
Harry wants him to look after those in the bar..

2] First thing Harry does is open his backpack and pull out the Placard. Note, Mac's reaction;

Mac saw the sign and his eyes widened. He looked at me, his face written heavily with consternation.

In other words, the sight of the Placard filled him with, feelings of anxiety or dismay, typically at something unexpected.
Then Harry picks up on him knowing what it was that he had just pulled out of the knapsack. But the mere sight of it shouldn't have filled him with anxiety, but Mac knows the drill, he knows it puts him on a team.
3] Harry starts to question him closely, not just anyone would know what the sign was.. Wait lets back up a sentence.. Harry tells Mac that what is out there can kill everyone, so they need his help.

Mac nodded firmly

So far so good, Mac isn't afraid to put his butt on the line for those people. Then Harry questions him a bit closer how does he know what it is.. Mac is unwilling to say..

Mac looked from me to the sign and back grimacing.

I take that to mean, Mac isn't afraid to stand at the door with his shotgun to protect those people.  However he doesn't want to commit to using the Placard.. Theory, putting his blood on the Placard commits him to sacrificing himself to save those people just like the Man on the Cross.  That is taking a side, one he had turned his back on long ago and got kicked out of Heaven for.  Harry clearly wants him to use the Placard, and now wants to know who he really is and tries to look at him with his sight.  Mac stops him, gentally says "don't hurt yourself.."  Doesn't say what he really is either.

No, Mac isn't upset because Harry has figured out what he really is..  After he takes his hand away from Harry's eyes, Mac steps back, resolved.

Resolved means Mac arrived at a decision, he is making a commitment, he is taking a side. Because
the power of the Placard is about this;

"It's embodied intercession. . .It focuses energy on an individual."
I said. "Something about pouring out the accumulated sins of humanity onto Christ, maybe.  Hang it up and it puts up a kind of threshold that will hold off just about anything supernatural, as long as the property's rightful owner is alive."

So to Harry the Placard merely is a way to protect the bar.  But to Mac, its about the pouring out of the accumulated sins of humanity onto Christ. Where Harry is merely guessing how it works, Mac knows, and he knows what it stands for, and yup, it is taking sides, the side of the Son of the Father.

[Griffyn612]

Nope, I'm just not seeing that way.  Sorry.  We'll have to differ.  I don't see it being anything like taking sides.  He's putting up a passive defensive measure for his patrons.  I don't think that phases him at all.  I interpret it as him just not liking Harry knowing, and having it be learned by others. 

If anything I could see him not wanting to get involved in big things for other reasons, and wanting to be 'out' of it, but I think that's more about remaining anonymity, which he's losing by Harry learning about him.

[Mira]

Nope, I'm just not seeing that way.  Sorry.  We'll have to differ.  I don't see it being anything like taking sides.  He's putting up a passive defensive measure for his patrons.  I don't think that phases him at all.  I interpret it as him just not liking Harry knowing, and having it be learned by others. 

If anything I could see him not wanting to get involved in big things for other reasons, and wanting to be 'out' of it, but I think that's more about remaining anonymity, which he's losing by Harry learning about him.

Willing to and committing to sacrifice himself for his patrons is hardly passive..

[Griffyn612]

Willing to and committing to sacrifice himself for his patrons is hardly passive..

Irs literally guest law under the accords, which he joined as a neutral party.  They're guests.  Allowing harm to them, good manners aside, would invalidate all that he established in opening the bar.

[Mira]

Irs literally guest law under the accords, which he joined as a neutral party.  They're guests.  Allowing harm to them, good manners aside, would invalidate all that he established in opening the bar.

But Mac would do that anyway, he'd stand there with his shotgun. 

[Griffyn612]

But Mac would do that anyway, he'd stand there with his shotgun.

Yes. Which isn't taking sides.

[Mira]

Yes. Which isn't taking sides.

Exactly, but putting his blood on the Placard and hanging it up, is.