I think its interesting how Bram Stoker chose Vlad to become dracula. The 'Dracul' name came from Vlad's father, I believe, who was in the order of the dragon.
Anyways, from what I was able to discern, he was only once documented as consuming the blood of a human. He always enjoyed locking people up in shackles, and one day he drained a man's blood into a bowl, and dipped his bread in it. This was more of a symbol of how he had power over him, though.