Hi guys, first time poster here but this is topic is something I've been stewing over for a while, and I haven't seen this theory mentioned before so apologies if it's already been spoken of and debunked.
I believe that Mac's full name (MaCanally) points to his true identity. The surname MacAnally (and its variations, such as McAnally, MacNally, and McNally) is rooted in the Irish Gaelic name Mac an Fhailghigh or Mac Con Uladh.
"Mac" in Gaelic means "Son", and "Failghigh" is derived from "fáilgheach" or "fáilghe," which convey meanings such as "poor" or "destitute".
Essentially his name would translate to "Son of The Poor Man" which could be interpreted as a subtle, respectful reference to none other than Jesus (or, at least, the divine being we know as JC - which could well be a mantle just like Kringle/Odin, and the hint that the Fae queens are aspects of Hecate).
This could be why he's "out" beacuse the last time he was "in" humanity turned on him. Let's not forget he also instantly recognised the "King of the Jews" plaque that Harry presented to him in PT.
I'm probably wrong but I definitely think JB didn't choose Mac's name by accident.