It sucks to be the savior.
Alex is half-human, half-something else, and while this would ordinarily make him of The Kin, his particular gene-set is utterly unique, and in fact, could only be conceived by the power of the Dream.
He makes his initial appearances in Notte, though they may be easy to miss. Not to worry, though; the book after Notte is based entirely on him.
(As an author-aside, he was my first fully-developed original character. I’ve had him in my head for 30 years, and it’s a delight to finally be able to reveal him to the world.)