Whoa, I love the current detail of the world (I also love that you're giving us some creative freedom with it).

As of now my concept for my Child is a rather apathetic creature. He likely never cared about humanity and their struggles, only seeing them as a means to an end. What that end was? I'm not even sure he truly knew. He was probably rather amoral and lazy, fighting only when it was truly necessary. I'm guessing those who followed under him had a rather hedonistic, if not nihilistic view of the world. I also imagine he was pretty crap at his leadership role, given his lack of care or concern for his followers.

He'd probably have been one of the ones who took a long time to pick a side. I doubt he wanted to get involved in any war, and likely didn't care much for both angels and demons. If I do go with this concept (and it works within the bounds of this RP) I'm not sure what side he would have ultimately gone with. Naturally I'd think he'd go with the demons, but I think the betrayal of the Seer might prompt him to go to action more quickly in the future.

Decisions... decisions..