This is just a quick writing exercise for anyone with writer's block. Get a piece of paper and a pen. Write down any questions you can think of, for instance: What is you favourite song, earliest memory or pet hate? List between 10 and 20 questions, then go and make a cup of coffee, do the hoovering or take the dog for a walk... I am now back with the prerequisite cup of coffee and a slice of bread and honey, here are some suggested questions for the vampire.
1. Do you see in colour?
2. Do you feel the cold? (I can't imagine Count Dracula in a cable knit sweater and a ski jacket.)
3. Earliest memory from before you became a vampire?
4. Where and how do you sleep?
5. What annoys you more, loud music or politicians? (Both)
6. If you could vote or do vote in elections, who would you vote for?
7. Do different people's blood taste different and if they do what is your favourite type?
8. What season do you prefer and why?
9. Have you ever read a book that changed your life or death?
10. Do you have an Internet connection? If so, do you go into chat rooms and pose as human?
This isn't a serious exercise, but if your vampire is humanised, rather than the demonic, kill all humans and drain them dry type, even if you don't need this information for the plot, it helps to create a fuller character in your mind as you write. Plus, it's better than sitting with a blank screen or piece of paper in front of you. Writing is like anything else in life, the more you do it, the better you are at it.
Try really hard not to force your character to be something. If you invent quirks just for the sake of it, this will show in your writing. Remember the back story is vital in vampire novels, it can justify or clarify any act preformed by the vampire. Anne Rice never introduces Lestat's back story until he gets his own book and he is transformed by his history from villain into hero without loosing the readers belief in the character. If you decide your novel is character driven rather than plot driven, any time you spend developing your characters with be rewarded with an enriched reading experience.
In the first paragraph, I added a piece of personal information, I was just about to get my breakfast. What did this tell you about my character? I like bread and honey, yes, but I rarely eat it. Why? You decide and just like that you have a whole back story for a fictional character based on a snippet of information.