Essentially down to Wizards and Guardians of the Gate. Perhaps someone even older or possibly unique.

I attributed it to each of these entities. Mac could be any of them. I realize it is a shot in the dark, but "unique" is about the only quality of the starborn we can really be certain of thus far. I don't think Mac could have gotten out from being Starborn if he were one, no more than Harry can be out from being Malcolm's son. I think he could have gotten out of being active in the supernatural world. I think he could get back in at any time, but it wouldn't be without dire consequence.

I need to re-read the series again. Reading through the context of everything here, this passage in particular really stands out. This is more than just recognition, its almost familiarity:


So then my question is, who would have had contact with the Outsiders to the point of being familiar to them? and of those, who would have the ability to choose to be "out"? The list would be very small. Essentially down to Wizards and Guardians of the Gate. Perhaps someone even older or possibly unique. Mac is DV's equivalent of Shepard Book.

There are a couple of WoJ's I'd like to share:
There is a WoJ that states Mac has never once done anything beyond the capability of a plain old vanilla human being.
[the Winter Lady] didn’t fare so well the last time a Starborn was running around.

If you haven't guessed where I'm going with this already, here it is: Mac could possibly be one of the previous starborn. One that helped Mab ascend to Queen of Winter, and received immortality or extreme longevity in exchange for his neutrality in future events. This would also explain his interest in Harry, his place in the Accords, and familiarity with many of the elite denizens that filter through his pub.

Isn't dumb luck Harry's calling card? Harry was likely not considering anything other than keeping them out of Nic's hands, the only thing Nic claimed he was after was the Grail, so that's all he needed to fulfill Mab's bargain.