Every once in a while Harry gets to speak with himself, usually when unconscious. ID Harry (stands for internal dialogue?) seems to observe things that Harry doesn't, and from time to time tries to warn him, but Harry seems to miss it.
I speak about ID Harry as if he is a different person, and in a way he is. He is part of Harry but isn't the same. He'd sleep with the woman Harry wouldn't. He's more like Bob I think. Anyways most of the things ID Harry mentions are observations that Harry seems to miss, but there are at least two things I can think of that ID Harry spotted that seem like more than just observations. Something more.
1. In Storm Front at the beginning of the book when he and Murphy are in the elevator together he looks at their shadows on the floor, and says "My shadow and Murphy's fell on the floor, and almost looked as though they were sprawled there. There was something about it that bothered me, a nagging little instinct that I blew off as a case of the nerves".
This to me sounds a lot like ID Harry warning Harry. For what? Later in the book he and Murphy nearly get killed in an elevator with the giant scorpion attacking. If true this was a bit of a prophetic feeling. Not an observation but a prediction of some kind. Harry does appear to sense an event approaching that involved he, and Murphy in an elevator accident.
2. Ascher and her Coin. Not even Mab, who was in person contact with Marcone was able to know that he had a Coin. Yet ID Harry was able to realize that Ascher had a Coin, and was trying to warn him. On some level he knew Lasciel was there, and if Harry let his guard down to a seductive woman (Murphy in his dream), he'd get killed.
On some level ID Harry is aware of things that I don't think can be chalked up to subconscious observation.