Finally, finally got a chance to read this, and wow, what a ride! The plot certainly kept me guessing (I suck at mysteries :-P), and while I knew right away that Newlin was Snape, I couldn't figure out HOW for the life of me. What a chilling solution you imagined.
I'm very glad Ginny didn't end up being the villain of the piece. I was nervous for a while there. But reading the other comments (and your responses) helped; I don't think I'd appreciated just quite how selfish Harry was at times in this fic, though I was troubled by his lack of concern for his kids. But I loved that moment near the end when he sees all the petty things that everyone else wants -- such a powerful statement there about Harry's own humanness.
Harry shivered. "Look at me."
Snape's eyes looked back at him.
Harry slid off his chair to kneel at Newlin's feet. He laid his head in Newlin's lap, and the hunger finally disappeared.
He smiled and breathed deeply of blue air.
Okay, whether he's being selfish or not, this ending just slays me. It's beautiful.