the horror

An element of horror is the concept of loss of female virginity.  The bloody key is a motif that runs through the different versions of this concept.  Linked with loss of female virginity is marital disobedience-- the fear of the husband [or robber] that the woman is going to somehow betray him.  that is why Bluebeard-- or the robbers- or the similar characters-- do not seem to trust their wives, and always manage to "catch" her in her lies.  Further linked with loss of female virginity is the notion of any kind of "transgressive desire" in respects to the female character.  She is supposed to stay in line, and if she strays, then she is always caught and "taught her lesson."

Another element of horror is the sheer psychotic rage on Bluebeard's character.  He seems utterly emotionless, or, as Tatar says, "abject" to his acts of murder.  He is absolutely heartless.  It makes him unhuman.

Overall, all the Bluebeard tales taint marriage with its threat of murder.  The Bluebeard tales make it out to seem like you can never get too comfortable with your husband or wife, because you can never trust someone when it comes right down to it.  Bluebeard, as Tatar puts it, "confirms a child's worst fears about sex."  With marriage or sex comes betrayal and murder, in the Bluebeard tales, and is rendered in elements in the tales such as the characters' anxieties.  In "Bluebeard's Ghost" Sly's nephew commits the ultimate betrayal, even though he is not married to Bluebeard's widow, he is the potential suitor, so the theme of elements of horror applies to him.  The concept of him dressing-up as a deceased man-- Bluebeard-- and tricking people based on that-- proves how sick and twisted his mind is, to an extent that is more than creepy to the reader.  The nightmares and anxiety that Bluebeard's widow has because of the whole situation augments the horror of the "trickery."