>>(Or is it only male vampires that are fertile?
>
>It is (and they are not very much so; it's really fairly remarkable
>that Victor and Remilia the Elder had two children within a mere five
>years).

You say that, but also just quite well documented that Remilia the Elder was a talented alchemist. One suspects she did some research, and then tipped the odds in her favour ;)

~Silv'

(Whether such research would be of any benefit to her daughter(s) is another matter entirely)