How does the supernatural mingle with the mundane in the bloody chamber stories? Examples of how/where Carter does this?

In Angela Carter's short story, "The Bloody Chamber," there are two specific examples of her use of the supernatural.

Details surrounding the major characters are relatively straightforward, however, the supernatural comes into play with regard to the key to the "forbidden" room. When the young wife drops the key in a puddle of blood where the bodies are hidden, the key becomes stained. When she tries to clean the blood off, crimson stains go down the drain, as if the key itself is bleeding, but it will not come clean.

When the woman's husband prepares to kill her, he takes the enchanted key and presses it against her forehead, where it leaves a stain, like a brand in the shape of a heart, between her eyebrows. It is as if the key has been harmed in some way in that it bleeds like a fresh wound.

In both instances, the key is enchanted; it becomes stained and will not be cleaned, and it bleeds not only in the sink, but onto the skin of the young wife's forehead, from where it cannot be removed. This power that the key seems to have adds a sense of foreboding to the story, for how can one hope to fight something that is supernatural?

It also adds to the sense of power the narrator's husband has: not just his physical power, but the sense one gets of his ability to know her actions without being with her. When he leaves his wife with the keys, she later realizes that he did so because he knew she would go into the one room that was forbidden. This might refer to a supernatural sense, or simply the man's ability to accurately judge human nature, and anticipate his wife's behavior.