I get the feeling that the six years between Skin Game and now wasn't just setting up Peace Talks and Battle Ground, but the eventual end of the series as well. This is clearly the opening of the final act of the Dresden Files. I mean, heck, Harry just about says as much once Ethniu appears.
Also goddamn Marcone keeps his cool in the presence of a literal goddess. There's only one thing that shakes that man, isn't there.