The “red stuff” they draw out of people isn’t blood, they don’t sustain themselves via blood, they don’t have any aversions to crosses or garlic, they don’t turn into bats or sleep in coffins, and mirrors play a huge role in their culture (magic mirrors anyway).
They are stuck up aristocrats though, so do feel free to slaughter most of them…just leave some of the good and cool ones like the Curator and Accuser alone.
Blood, Shadow, and Void Magic are very close when it comes to behavior.
It’s Difficult to say Which Cosmology Blood Originated or where it is alignment resides, Some Say Blood is aligned with Life, some say It’s aligned with Void, and some say it’s aligned with Death.
Overall throughout all forms of Fiction the Blood cosmology often depicted as the most Dangerous; rendering Mortal minds who attempts to study it to complete madness.
To make an example how Dangerous Blood Magic could be, the number of mortals who studied the Void Magic and kept a calm and collected mind heavily outnumbers those who done the same with Blood magic 25 to 1.