I'd say Lady van Tassel because I seem to understand everyone else alot plus than her.....
I think she's a complex character because there is alot of hate and resentfulness inside her which makes her into a monster who "offers her sole to satan"! She also uses a very thought through method of killing her victims instead of just killing them herself as we know she's capable of (as she kills Sarah and her sister) she decides to do it par raising the hessian from the grave. She also kills her own sister which shows her strange complicated twisted nature! Anyway I think her! :)
