The house is a metaphor for the subconscious mind. When a vampire is invited into one’s house, it is symbolically invoked into one’s personal subconscious, where it is then free to feed upon one’s spiritual vitality. This is why the vampire’s visitations occur overnight, when one is asleep and dreaming, and most vulnerable to entities in the subconscious mind. The coming of the female ghost-vampire unfolds a tale of forbidden, exclusive female desire. Carmilla, in fact, represents the subconscious sexual instinct Laura has had to repress.
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By letting the vampire enter her dream-reveries/psyche, Laura is invoking a phantasm that can satisfy her secret repressed desire and destroy her at the same time in order to expiate her sense of guilt. But the descriptions of her vampiric visitations in terms of an unspeakable jouissance hint at the troubling fact that she might not want to be cured from her ‘evil’.
—Laura Sarnelli, Ghostly Femininities: Christabel, Carmilla, and Mulholland Drive