The Book of Life by Deborah Harkness.
Book 3 of the Souls Trilogy, this does not stand alone. However, for fans of the series, it is a great ending.
In Book 2, (Shadow of Night) Diana and Matthew returned to present time, pregnant with twins, to find the magical alchemical manuscript Ashmole 782, The Book of Life, to witches, vampires, and daemons. The new family spurs them to pursue creating a legal marriage out their illegal union of witch and vampire. To do this, they must create a new family branch, and pull all creatures closer in understanding their possibilities and origins.
Matthew’s blood disease becomes center stage when his son Benjamin Fuchs returns to create havoc, trying to destroy the family. It is this vampire that generates the central problem, suspense, and violence. And gives us an amazing ending.
I disliked dragging an entire genetics class into Matthew’s research. It did not make sense for the need for secrecy; it did help the reader to understand genetic background. Overall, the writing was not as solid as the first two- perhaps she was rushed into the third? It’s just that we all wanted a satisfying ending and soon that we forgive Harkness.
I did like the change in Diana, even in Book 2, when she became pregnant, and in this book as a mother. Always a strong character, she shows a bit of “tiger mom” aspects.
A word to teen readers: the first in the series is wonderful and accessible for teens. This book, perhaps, is for older teens.