"Bloodlines" is a young adult urban fantasy novel series written by Richelle Mead. It is a spin-off of her highly successful "Vampire Academy" series and consists of six books, beginning with "Bloodlines" in 2011 and concluding with "The Ruby Circle" in 2015. The series follows Sydney Sage, an alchemist tasked with protecting the vampire world from humans, as she navigates the complexities of her duty, prejudice, and unexpected alliances with vampires. The storyline delves into themes of friendship, identity, and love, expanding the rich world built in the original series. Fans of "Vampire Academy" embraced "Bloodlines" for its intricate plot and character development.