You'll have to forgive me I didn't read all the comments so I hope I am not repeating something.
Serack, some questions for you if you can answer them.
I can only answer with my impressions. Until I hear Jim say something at least.
Do you think Fitz will be able to control the change (or be trained to control it) or have his human consciousness afterward?
I've already put some thought into this one, and I think that might be quite likely, although knowing how Jim treats Harry, he's going to get smacked around a bit before that can happen.
Does he have a soul or some mixed hybrid of one?
*raises eyebrows* That is a good question... Hmmm... The closest thing to a scion we have seen soulgazed is Thomas I think, and that doesn't give us much of a precident imo... I'd love to ask Jim, "If Fritz has his mother's eyes, can he be soulgazed?" Maybe it should be "Can a scion of a wolf and a Loup Garou be soulgazed?"
Edit: I'm pretty sure Harry has stated a few times how he wasn't worried about soulgazing a fae, and I think he made similar comments about the rampires... What other beings can he not soulgaze with?
Would this explain why he was able to hear Harry?
I'm using this as part of my argument for explaining his parentage, so yah I think that is very likely. Stuart did say that 1 in 10 dogs can sense spirits.