How do you think the blood drinking works? Is it more of a pierce the skin with the teeth and suck the blood with the mouth or do yuo think the teeth act as straws?

(☆▽☆) I actually have thought about that a lot. 

-When not in use, the fangs are actually slightly retracted. Similar to a snake’s they extend when the vampire is about to bite. There’s muscle tissue and/or tendons that control this process, and it’s one of the reasons why fangs are very sensitive. 

The fangs themselves are mostly hollow, with a small hole at the tip, a slightly larger one toward the very back of the fang, and spiraling ridges along the inside. When the vampire bites, the hole at the tip functions similarly to a needle, and blood runs up though it. The spiral ridges create pressure (which is intensified by sucking) that draws the blood out of the veins and up into the mouth. The hole at the base of the fang is where it exits, and that hole is covered by tissue when the fang is retracted, only opening up when the vampires bites and the fang extends. 

Fangs are extremely sensitive, partially because of how thin and delicate they are, and partially because there is tissue and muscle directly connected to them. Any damage to fangs, even a small bump at the wrong angle hurts, and actually having them removed (like in Pet Au) would be absolutely excruciating.