Someone posed an interesting theory on this other site today.
What if Lilith was first a fairy who was turned into a vampire. Essentially, she "lost her light" and turned into a vampire as she was no longer a fairy without the juice. This would explain why they would high off her blood and why Claude tried so hard to convince Sookie to hold on to whatever power she had left. It might also explain how Lilith is appearing as she is when they drank the blood. As Godric said, he evolved when he died or hell, he probably figured it out before he died.