SPOILER ALERT
I just finished this, Auntybooks. You've done such a good job with it and I'm pleased there's going to be a sequel. I'll confess that in general I don't like to read books that have majorly evil characters in them. I know it's wimpy of me, but there's enough evil in the world that I like my pleasure reading to be more pleasant. (It's why I couldn't bring myself to read the last three HP books.) But Tyger, Tyger has enough interesting characters that I cared about that I had trouble putting it down. I agree with AnneN that it reminded me of Madeleine L'Engle's series. I also appreciated the spiritual aspects of it.
I wanted to tell you that the part that really touched my heart was the description of when he couldn't remember the death. "All the pain of knowing she was dead would come flooding back, all the grief, new and fresh when he heard it again." My father had Alzheimer's and that's exactly the way it was with him. Because he didn't remember Mom's death, every time he heard it he had to experience all over again the heart-breaking grief of losing the person he'd loved for more than 70 years. Over and over again. And because I was the one who was having to tell him, it broke my heart, too, to see him suffer so. It seemed so unfair that with all the other indignities that go with Alzheimer's, that he had to suffer that pain as well.
So, yes--you got that part so right! And the image of something evil sucking the memories out one by one until a person is gone is the perfect image of Alzheimer's. (As I said at the beginning, I have a general preference for happier books, but I did really like your book. <smile>)