Well, let's see if we can at least narrow down who's probably in whose favor:
The Archive: She's inclined to favor the White Council and Harry in particular, which puts her in Winter's corner at least where he's concerned. If she knows that Summer was actively hindering Harry from saving her from the Denarians, that would put her against them.
The Denarians: It wasn't clear to me whether they were expelled as a whole or it was just Nicodemus -- remember like half of them were involved in breaking the Accords. Anyway, they probably don't have many in their corner.
Donar Vadderung: Definitely on the White Council and Winter's side, given his friendship with Harry (and that he's Santa).
Winter: With Harry as a go-between, they're probably most inclined to ally with the White Council, especially considering Chichen Itza, where not only the Winter Knight but the Leanansidhe helped win the White Council's war. Mab's position on the other signatories aside from Vadderung would be murkier.
Summer: Now, them I see as a wildcard. They don't have any clear allies that I can think of, and Titania's apathy has no doubt been affecting their relations to the other signatories. It also depends on who she sends -- ironically, most of her known retainers are inclined to like Harry personally, and by extension be softer on Winter than she might want. My prediction? Either the Lady and Knight will show up to represent Summer (giving Harry a possible ally), or Titania herself will show up and throw a huge wrench into Harry's plans.
Black Court: May not even be signatories; the last time the Accords were revised was in the 90s, well after they were broken as a nation.
Red Court: Well, they're all dead, so if there's anyone speaking for them at all, it'd be a surprise.
White Court: Given the events of Turn Coat (where the Senior Council and Lara worked together and uncovered a plot to try and turn them against each other) and Changes (where the prince and hero of the White Court assisted in winning the Council's war), the White Court probably enjoys a relatively friendly public relationship with the White Council. Lara is no doubt scheming behind the scenes, but on the face of it, I think she considers it good business to make nice with the White Council for the moment.
The White Council: As mentioned, I think they can mostly count on allies among the Archive, the Winter Court, Vadderung and the White Court.
Svartalves: I don't know much about them; given their Norse mythology origins, however, I think they're probably on speaking terms with Vadderung. That Molly is a member of their nation probably puts them on good terms with Winter, too, if they weren't already.
Drakul and the rest, I don't know enough about to speculate.
The Fomor: Yeah, nobody's a big fan of theirs. But I wouldn't be surprised if some behind-closed-doors deals had gone down.
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