Always young people want to change to something... Anyway, vampires or any other mythical don't exist and obviously you cannot change physically into one. Vampires, as I read somewhere on the forums, are existing in the astral plane. I doubt a little, because there is no proof, buy I'm missing the point of the subject. I have a useful philosophical suggestion to put here: "Imagination brings ideas and ideas brings creations. So you cant use imagination for creation". That's what I wanted to say. Blessed be ;)
There are mythical vampires which do not exist and you obviously cannot become, and there are real energy vampires who are permanently sick people and which you could theoretically become if you damaged yourself enough.