I'm re-reading the Repairman Jack series currently, the Adversary cycle, and a few of the novels and short stories from the "Secret History." I'm on By the Sword right now. But I got to thinking, since the Ally, up to Harbingers was trying to prune Jack's spear, I thought that the Ally might have be somewhat behind the events in The Haunted Air. The stones in Menelaus Manor were revealed to have been taken from the Keep, which I believe have some sort of spiritual holding power, as the complete configuration held Rasalom for (going from memory, I hope it's accurate) 500 some odd years, the murdered children stayed on in the house as well as one of the Kenton brothers (I think it was Lyle but I'm not sure) from the effect of the stones, and (I haven't gotten to the point of re-reading Reprisal yet) I believe that Rasalom (as "Sara Lom") murdered the kid whose voice torments Father Ryan on the telephone using the power of the stones. It is my belief that the Ally used the murdered girl's spirit in an attempt to take Gia's baby.
Or, it was a "tainting" of the Keep stones by "Sara Lom," who is also a necromancer, which means that the Ally and the Otherness were working together (at least had complimentary goals) to a) prune Jack's spear and b) cause pain and discontent through sheer mayhem.

BTW:
I noticed a couple of discrepencies in Infernal. I marked the pages but my coworker is reading the series for the first time (he's on Infernal now) and I only remember one of them off the top of my head. Abe makes a comment about not hearing of Johnson, NJ, when, as we know from Jack: Secret Histories, he met young Jack there at the antique shop. This is probably because FPW wrote this book prior to the young adult series so I take inconsistencies like that in stride. Hey, it's a great series regardless. And, I was and still am stoked that FPW tied in Black Wind to RPJ. That was one of my favorite stand alone books.
Anyone have any speculations on my The Haunted Air theory?

SPOILERS: The way I saw it back then, Tara and the ghosts were resurrected by the Ally the instant Gia crossed the threshold. The crosses in the Keep were plain metal. Over the course of 500 years they absorbed some of Rasalom's Otherness. Thus the one Gia found was able to ward off the Ally-fueled ghosts. Just the opposite of Magda being able to ward off the Otherness-fueled zombie soldiers in The Keep with Glaeken's hilt. (Yeah, it's contorted but I was going for an inverted symmetry.)

Thanks, FPW! Your explanation does still validate my idea that the Ally was behind the baby-snatching attempt, as opposed to an assumption that Rasalom, as "Sara Lom" and one of the anagrams that Jack doesn't catch, was involved. But, then, if the Ally brought forth the ghosts when Gia crossed the threshold, then the bottomless pit that was seen through the crack in the basement floor was perhaps a hole into the Ally's reality, rather than identical to the other holes which led to the Otherness' realm. Hmm. Maybe I'm just overthinking things!
By the way, I must admit it's really freakin' cool to have you answer my post!

I don't have much to add except to agree that it's really freakin' cool to have FPW answer our posts. This is a great forum!