Infernal reminded me of Hosts. Not for the plots, mind you, but for the author's reining in of the characters. Writers on the board know of the characters that they create literally taking over the story and having to rein in the characters to keep control over the plot. In Hosts, as I recall, fpw let the Kate, Jack's sister, storyline unfold and Jack was almost a subplot; I also recall his having to rewrite the ending so that Jack could reassert himself into the finale and retake control of the story. (I'm curious how the original ending was played out before the rewrite--is it still in your computer, Paul?). Anyway, I still consider Hosts to be Kate's book, with Jack along because it's his series.
In Infernal, the Tom (Jack's brother) storyline also takes control of the book early on, but with the release of the Lillitongue, the story shifts back to Jack and Tom's story reverts to subplot. If I'm correct, fpw kept a tighter rein on the character of Tom, so that Jack, Gia, and Vicky's story would play out, although Tom does get more page-time in the book (page-counters can point out my error, but that's how I remember it) albeit with Jack at his side most of the way.
Also, the elements common throughout the RP series (the old women, the dogs, an otherness monster, etc.) were somewhat inverted in Infernal: A ten year old girl instead of an old woman; the midsection, or Lillitongue, (symbol for pregnancy) the monster element (leaving Tom to be "reborn" as he is enveloped by the girl's "womb" perhaps). So, instead of an otherness monster, or a creature of destruction, we have a "Mother Earth" monster, or a creature of creation. I don't think we've seen the last of Tom.
Infernal was more subtle than the other books, more set-up than unfolding. With Kate's death there was a finality; with Tom's there was a hint of a beginning, as I said earlier, "a rebirth." Did Tom die? Who knows? But as Hosts, to me, was a self-contained Kate story, Infernal was a stepping stone to what's to come in the unfolding of Jack vs. the Otherness, as well as to Nightworld. I enjoyed the subtlety of Infernal, as one can only enjoy that serene calm before the storm.
AC