[CWatkinsNash]

Originally Posted by AlbertaCowboy

I don't know if this is likely.

Spoiler:

When Harry threatens Mab with imprisonment at the end of Cold Days, Demonreach rises up silently but threatenly towards Mab, who then backs down. If Mab was the original imprisoner, I don't think Demonreach would have made any movement, nor would Harry have gotten away with the threat.

Maybe, but

Spoiler:

The various factions, even the opposing ones, do make deals, and will work together for the duration of the deal and not a moment longer. Something like that could have transpired, especially when you consider how Harry came to be kept alive in the first place.

Demonreach was created for a specific purpose - it, or rather its genius loci that controls its manifestation (should one choose to address that aspect separately from the island itself) could very well cooperate in something that furthers that purpose. But once that's done, the deal is over and it's not beholden to anyone. Mab would have no special protection at that point. So I don't think its menacing gesture rules it out as a possibility.

Just thoughts, probably inaccurate ones, but the depth of frenemy politics in the Dresden world allow for so many oddball alliances.