This could do in either plot, and/or, character development but I thought this would've been the best place for this thread, feel free to move it if any Admin disagree. Vampires, and creating them, now I writing a vampire story at the moment just as a get going kick start, but what I've noticed is that when creating your vampires you obviously need a plot for them (not your story, but for your vampires) as you need to know how they were made into a vampire, were they bitten? Did they just turn? Born that way? There're so many vampire books that I fear a lot of the time that there's nothing left, so my advice for this problem is research. I found out my way of making them into vampires is from a disease that I was reading about on wiki from looking at vampires so I used that. How do you all do it? Am I copying off of someone else? The only vampire books I've read, and own, are Darren Shan (Cirque Du Freak), and The Twilight Saga.
I am using vampires in an upcoming novel. The way I would do it is to research vampire folklore and legends from Europe. You could then, by using the legends as inspiration, develop your background for your characters. The disease idea can work if you develop it further i.e origins of the disease.
Do you have to include an origin story? No. You can leave that a mystery, possibly even to the character. Discovering his or her origins could even be a motivation, and the character need not succeed in order to make a good story. Or the origins of his "drinking problem" can be simply irrelevant to the story, in which case you should leave it out.