When you finish the cure for vampirism (side quest)(in skingrad so you know )the 
count will give you the cure for vampirism and 2500 gold pieces (after you take 
the cure). If you talk to him and you go to the word reward it will continue to 
give you 2500 gold pieces. Every time you chose that reply P.S NEVER (after the 
qwest )try to read one of his book's or he will attack you and you won't be able 
to talk to him again.