Well, I am at a loss, given that WoJ. 

Mab names Harry Emissary, Titania responds with the Gruffs (who attack Harry before Mab notifies him).  Both of these events occur before Marcone is kidnapped and the crisis is created. 

Any theory that doesn't account for this seeming discrepancy is likely doomed. 

Two additional points that might be a problem for the theory:

(1) Mab tells Harry that she doesn't know who took Marcone:

This is problematic for the theory I think because it requires a trip to Demonreach.  There is no reason for the story to go to Demonreach, except for Ivy, who is naturally Harry's go-to Accords Arbitrator. 

However, the number of powers that COULD contain Ivy at all AND need Demonreach AND be an accords member has to be very limited, and probably pretty close to exclusive.

To illustrate, Summer wouldn't need Demonreach, nor would the Lords of Outer Night.  Mavra or a full power Lord Raith would have no hope of containing her.  Cowl on the other hand probably could do it using DR, but Harry can't summon Ivy to arbitrate with Cowl.

Counterpoint:  Mab might be referring to the ambiguity of whether the Denarians OR the BC-infected Denarians are calling the shots.  After all, she isn't stupid and a big giant hellfire pentagram is what Harry would call a clue. 

Counter-Counterpoint:  There isn't any reason for Mab not to tell Harry this, if it were her belief.

(2)  There still is no really solid explanation for why Mab declared Harry her Emmisary Before Marcone is taken.

It really doesn't seem like Mab can just declare someone an emissary for no good reason.  Just seems like there has to be some crisis in the fae courts that allows them to call in special agents.  But, Mab tells Harry that he has been chosen as Emissary for the purpose of recovering Marcone.

That means that she had to know of the plot before it was executed, hours in advance, which returns us to (1).  She somehow knows about the plot, but not who?

Counterpoint:  Perhaps it rather suggests that Titania was the first to act.  Perhaps the Gruff's initial hit on Harry was BEFORE the Gruffs are named Summer's Emissary.  So, Summer takes a shot at Harry and fails.  Meanwhile, Marcone get's snagged and Mab declares Harry Emissary.  Titania goes with the Gruffs since they are already out and about hunting Harry.

Maybe Titania knows what Mab is planning viz. Harry and is engaging in some pre-emptive strike to foul up Mab's plan. 

OR, perhaps it means that Titania is in on the Denrian-Demeter plot against Marcone.  Titania's part in this is to get Harry out of the way BEFORE Marcone is attacked. 

This is some excellent thinking. 

WoJ is that Mab won that game.  I'd say with a walk-off grandslam.

Really interesting lines of thought here.  I think that Gatekeeper's warning ends up saving Molly, saving Harry, saving Michael and saving the White Council (again). 

Let's focus on Molly Primary Effects first:

Molly's abduction: (1) removes her from Chicago and sends her to Winter -- where time flows differently (and as controlled by the Winter Queens); (2) her fear is fed upon and essentially drained.  In other words, Molly is made more open to turning herself in (lower fear) AND her trial is delayed. 

Secondary Effects:

(A) Harry is forced to mentor Molly.
(B) The White Council fails to execute Molly
(C) Michael saves the White Council from being crushed. 
(D) Karrin Murphy's police career begins its multi-book slide into the trash-heap and her new career in knighting opens.
(E) Lasciel's Shadow later witnesses the example of Molly "defying her nature." 

The White God wins on every front.

Now let's focus on the BC:

(A)  BC is making a play for Molly.  Molly is encouraged by her "friend" to consider using fear as a motivation to avoid drug abuse.  The seed is planted in Molly to use black magic "to do good." 
(B)  BC realizes that any Black Magic in the US -- particularly on the doorstep of a warden -- is going to be detected.  Therefore a fall-guy is needed.  So that the WC won't realize that Molly is behind it. 
(C)  Madrigal Raith is set up to be that fall-guy.   
(D)  Suborned Fetches abduct Molly and notably kill the Djinn/Lawyer cutting any link between the BC and Madrigal Raith. 
(E)  Fetches bring Molly to Arctis Tor -- which has been recently assaulted by the BC. 

So the questions we are left with are (1) why attack Arctis Tor at all; (2) why bring Molly to Arctis Tor after the unsuccessful assault. 

As to why attack Arctis Tor, clearly it was not truly an attack on Mab.  Attacking a being of that kind of power -- in her place of power, surrounded by her retainers -- is not a winning strategy.  Therefore, it was not an attack on Mab, but something else -- a diversion .... or a RESCUE!

Yes, the BC and Harry were both mounting rescue operations in Arctis Tor.  The BC was attempting to free Lea before she was properly chilled out by Mab, failed and was beaten off.  (Ironically, Harry and Thomas almost free Lea).  This leaves several possibilities for why Molly was even at Arctis Tor.  Either, the BC decided that Harry might free Lea if brought to Arctis Tor in the right mindset or Scarecrow expected the assault to be ongoing and that Molly had some kind of role to play. 

Justiciar

Your premise is actually pretty close to a movie called Skeleton Key starring Kate Hudson.  The evil plot only succeeds in Skeleton Key because Kate Hudson's character has been slowly brought around into believing in Voodoo.  If she remained an unbeliever (as she had been in the beginning), it couldn't have worked on her.

Basically, bail is set (or not) by examining the ties the accused has to the community, their economic circumstances and the nature of the crime.

So, consider the following examples:

A -- 30 year resident, owns home, multiple family members, middle class back ground, some kind of accidental death (i.e. manslaughter) -- low/no bail;
B -- Travelling salesmen, knows no one in the community, no money, Murder II -- reasonably high bail because of flight risk
C -- World travelling billionaire with known ties to non-extradition treaty country -- super high bail, maybe remanded until trial (particularly if extremely henious, violent Murder I)