I’m a big fan of Dan Simmons (his horror AND scifi), so it may come as a surprise I hadn’t read Children of the Night before. It was great, a scientific vampire novel, like if Crichton in his peak would have made a book about vampires. Set in Romania right after Ceausescu’s fall it’s also a fascinating look at the country then. Simmons travelled in Romania extensively in 1990 researching the book.