I could discuss any theory all night long or at least nod in the right places while the majority of the discussion happens over my head. I am partial to the "Mac=Angel" theory and the "Warden of Demonreach being a mantle that Harry has not fully explored yet" theory.

In my opinion a mantle must have 5 things (but I reserve the right to add more if they occur to me):
1. Power
2. Purpose
3. Limitations
4. Belief
4. Recognition

Now these five things are separate, but tied to one another and can cover some of the same areas. First comes power. A mantle must be invested with power, otherwise it is just a name. Power must be invested to create it (ie WoJ about the Erlking creating a knight from his power) and must remain with the mantle. The power does not have give the mantle holder a big boost in physical power like the winter knight mantle. It can be in the form of knowledge or responsibilities.

Number 2, mantles must have a purpose. Even if that purpose is to act as the mantle creators proxy. The purpose can be anything the mantle creator desires, but it should be defined and if disobeyed their should be consequences (Slate as Winter Knight).

Number 3, mantles must be created with a specific limitations in mind and should be revoked if necessary. That links the mantle to the one who created it and prevents the mantle holder from using the power indiscriminately. For instance, Harry can do his own things with the winter knight mantle, but he loses it if he crosses Mab or Winter Law (as seen in Cold Days). Harry also loses the mantle if he is pierced by iron. This should also theoretically keep the mantle holder from turning on the mantle creator.

Number 4, a mantle should be believed. My personal WAG states that mantles are somewhat powered by belief. That helps power the ongoing mantle for its daily actions. For instance, most people believe the Winter Knight to be Mabs enforcer, thug, assassin, etc. If Harry is acting in accordance with that he remains empowered. If he acts completely contrary to that his power is diminished. Belief by people aware of the mantle and the mantle holder can slowly change the mantle. This is Harry's hope for himself with the Winter Knight Mantle.

Finally, number 5, recognition. The mantle must be recognizable as a mantle and as belonging to a certain faction or person. The winter knight is recognized as a part of winter and must act in accordance with winter. If the Erlking created a mantle it would be associated with him and his interests and would lose power if it diverged.

As a final note, I use all of these to support my opinion that The Warden of Demonreach is a mantle held by Harry.

I see Mirror Mirror as an opportunity for Harry to get a broader understanding of the role he has played in people's lives, possible secret knowledge that is relevant to his world, and maybe an ace-in-the-hole object of power. Wizards hoard their secrets like dragons hoard their gold.

I'v always liked the idea of knowledge being power in the Dresden Universe. It brings to mind a WoJ that deals with the White Council members holding back what they can really do in case it ever came to a fight and another one that deals with wizards not telling Harry certain things or correcting his misunderstandings of magic because some things should be learned and being leery of giving Harry that "power."

Oh come on. Green Lanterns skill set is too limited. It's all just imaginary images enforce by willpower. Admittedly Harry uses his willpower and emotions to empower his powers, but he has a hell of a lot of range across a different spectrum than Green Lantern. Notably in that Green isn't his only colour. He also has you know... magic. Plus Green Lantern doesn't have a city to protect and be Guardian over.

I went with Dresden as Green Lantern. My reasoning: Number 1, will is what powers a green lantern. We have seen Harry use his will in numerous situations both mental (with Lash and with the outsider in Cold Days) and physical (facing down Mother Winter and her mental bonds in Cold Days). Number 2,  lanterns use their will to create constructs to fight with. Kind of like what Harry does with soul fire. Furthermore, Harry uses a number of physical constructs that he pours his magic (directed by his will) into. Number 3, Green Lanterns police a sector of space. Harry initially starts out just "policing" Chicago, but he has transitioned to much more. First a region of America as a Warden Commander. Then all of America via the Paranet. Followed by being The Warden of Demonreach responsible for the big bads drawn from all over. Now he the Knight of Winter which covers almost half of the Fae (in addition to his White Council duties). He has moved beyond being the "Batman" of Chicago (a role I would actually give to Butters pre-KotC). He is responsible for a huge "sector of space" a la Green Lantern.

@raidem, I'm sure you have already considered this and posted about this somewhere else so forgive me, but how do you reconcile this WOJ with your Mab/Murphy theory?

2014 AMA
Can we get a break down of the biological relationships between the various Fae Queens we have seen on screen? Of particular interest - Maeve and Sarissa, were they actually Mab's kids (biological sense)? If so, who was Mab's baby daddy?

Mab and Titania are actual twin sisters.
Maeve and Sarissa were twin sisters, from Mab. Their father was an Austrian composer and musician who died young.

Anything is possible until it has been disproven in story or WOJ, but I doubt this. As Rasins said, it seems like too much job for one man. In addition, Rashid presumably uses magic with a similar basis as Eb and Harry (with a different focus of course) while Odin most likely uses a rune based magic. I know that practitioners can learn different types of magic, but I doubt Odin would take the time.

If he does, I think the mantle should be called "Warden" and its primary purpose the capture and imprisonment of the bad guys.

A forum moderator has a duty to all forum users to be fair and impartial, but the obligation to remain a moderator is only to the site owner that hired him/her.

Similarly, as WK Harry owes fealty to all of Winter, but his obligation to remain WK is only to Mab based on the Changes deal. The SK deal with Mab is three tasks in exchange for all debt to Mab ceasing. That means if Harry completes a third favor, his obligation to remain as WK ends.

Apologies in advance for the length of the post. Cozarkian, are you saying that the Changes deal is completely separate from the previous favors/obligation set-up with Mab? I always saw it as a continuation. If so,I am a little confused about the chain of events with regards to this debt.

Harry owes a debt to Lea. He is able to forestall her for a year and a day at the end of GP by taking the poison. Lea is forced to sell that obligation to Mab due to her power increase from accepting the knife from Bianca in GP. Mab comes to Harry in Summer Knight and offers to erase the obligation in exchange for three favors. Harry accepts after a few conditions. The first favor is to act as Winter's Emissary which he completes. Then (in SK) Mab makes the Winter Knight offer:

"We have a traitor among us," Mab purred. "And he will be dealt with accordingly. After which there will be an opening for a new Knight." She watched me and said, "I would have someone worthy of more trust as his successor. Accept that power and all debts between us are canceled."

To me, this means erasing the obligation Mab took from Lea and the two favors Harry owes Mab for that obligation. Mab calls upon Harry again in Small Favor to be her emissary in the matter of the Denarians taking Marcone. She again makes the Winter Knight offer to Harry:

"Unless you should agree to take up the mantle of the Winter Knight," Mab said, smiling. "I should be forced to choose another Emissary if you did, and your involvement in this matter could end." This is followed by:

She tilted her head to one side and stared at me. "One day, wizard, you will kneel at my feet and ask me to bestow the mantle upon you."

"But not today."

"No," Mab said. "Today you repay me a favor. Just as I said you would."

Harry once again completes this task removing another favor leaving one still owed to erase his debt to Mab. Finally in Changes Harry calls upon Mab. He offers to become the Winter Knight with one condition:

"That before my service begins, you restore my body to health. That you grant me time enough to rescue my daughter and take her to safety, and strength and knowledge enough to succeed. And you give me your word that you will never command me to lift my hand against those I love."

Mab accepts, Harry kills Slate, and then Mab and Harry "seal the deal." Granted, at no point do either Mab or Harry mention this taking away the third favor owed or erasing Harrys previous obligation to Mab. Yet, based upon previous encounters this would erase Harry's third favor and his previous obligation to Mab wiping that previous slate clean.

My understanding is that the Winter Knight deal erased the obligation and favors and thus completing another favor will not negate the Winter Knight deal.