The op reminds me of my theory of in and out in some ways. My in out theory was that in a set of realities there exist a subset of outsider dominated realities but where it is not yet game over. It's just the immune system in these realities have a very high nemesis viral load, so I call these and the characters within it out. The realities where insiders have advantage is where the nemesis viral load is limited. So I surmised that there is a IN Mab and an OUT Mab. Both have yet to give in to nemesis but OUT Mab finds herself compromised by nemesis. And there will be a struggle between IN and OUT Mab to control the greater spanning mantle.
Anyways back to the OP, I like the idea that Outsiders take pieces they subvert in one universe to use against another. It would be like outsiders using cat sith against creatures in another next iteration of a universe.
I too had a similar idea about the black court before it was apparently joshed by woj. I had the idea that the black court were refugees from the outside, from another universe. Now that we know they seem to in part come from count Dracula and maybe his own inherited essence going back to his father drakul. I could wonder if perhaps darkly escaped from another universe to land here.