The Cabal Book of Blood Stories might explore the concept of blood in terms of sacrifice. It could show how different characters in the stories are willing to sacrifice their own blood or the blood of others for various reasons. This could range from trying to gain favor from a powerful entity to saving a loved one. For instance, a character might believe that by offering their own blood in a sacred place, they can break a curse that has befallen their family. The book could also explore the different cultural and religious beliefs surrounding blood sacrifice within the context of the stories. Another aspect could be the idea of blood as a bond. It could show how the sharing of blood between characters creates a unique connection, whether it's a bond of loyalty, friendship, or something more sinister like a pact with a dark force.