I'm starting to wonder if there will be future ramifications to Harry's decision to make himself corporeal near the end of GS.
This ties into Lea's existance in both the Mortal and "GS plane" in my mind. I'm thinking about how Lea can be running around in the NN and go from where she normally might be chilling, and then traipse into a ghostly portion of the NN that parallels Chicago. From her perspective, she might be tromping around in the Fae realms still, but Lea can percieve Agatha's influence on the ghostly "plane" and influence things there. She might even be able to chose not to be burnt by the flames in Agatha's pocket portion of the NN, especially since Agatha has pretty much perished by then. However, Harry's being there might conflict with that and cause the burning to transpire due to his perceptions of it doing so.
So now not only has Harry traipsed around in the "GS plane," and the higher "angelic" plane, but he has chosen as a noncorporeal entity, to become corporeal in-between those experiences, and then went back to his physical body. So Harry might not even have to open a "gateway" to get to those other "planes" but rather might be able to alter his reference frame so that he exists on more than one at a time not unlike Lea.
Of course this might come with a cost to his mortality or some such, but then he might have already chosen to take on that burden when he... corporealated (yah, I think I just made that one up) himself near the end of GS.
