The sad thing is that works like Jane Austen's are in the public domain, so anyone can do anything they want to them.
And it's one thing to use spirits and visions as dramatic devices, yet it's quite another to intrinsically and significantly alter a story's major protagonists, like, oh, making them zombie hunters.
But then, I have similar problems when it comes to the sort of DS fanfic that turns Barnabas into some sort of invincible superhero who's capable of succeeding at doing anything and everything while it completely ignores what a flawed and tortured man and oftentimes screw-up he truly is. That sort of DS fanfic steps much too far away from the character of Barnabas as he was always drawn on the series.