This is a very interesting idea...
The fact that the cores are sentient is a new concept, but I think that it could have potent consequences... I wonder if said cores will communicate often with their hosts, or only occasionally... (if they will be like the nagging little voice in their head ;-p)
And we have a dark Dumbledore (the first chapter hinted at it, but the second confirmed that).
I was about to say (I'm writing as I read) that we will have some anti-Ron, but it seems more probable that it will be anti-Weasley... Good :-D
I was half expecting Poppy to become like Harry and Hermione (connexion with their core) when they removed her mark (and yes, just writing it gave me the feeling I was talking about a death-eater...)
I'd love to read more! Please, update soon!