When a vampire nears 16, they enter the Dreamworld. There they are confronted by slayers and the Grand High Vampire (who is not the actual one, but someone they look up to). Legend has it that if a vampire dies in the Dreamworld they die for real.
Vlad's version of the Dreamworld looks like a ancient shady forest. In his dreams the Branaughs are the slayers but Robin is his guide. Vlad enters the Dreamworld when he is thirteen or fourteen, which, according to Ingrid, is much too early. It's there that he finds out he is the Chosen One.