"The Thing on the Doorstep" is a story by H. P. Lovecraft, published in 1937. The story starts with our narrator, Daniel Upton, explaining to the police why he's just shot and killed his best friend, Edward Derby.
Upton recounts his lifelong friendship with Derby, which took a turn for the sour when Derby married a creepy young Innsmouth woman named Asenath Waite. Asenath's father Ephraim dabbled in forbidden sorcery, and it looked like Asenath was following in her dad's footsteps, performing mysterious occult experiments that caused Derby to become more and more unhinged...
This short story provides examples of:
- Aerith and Bob: Edward Derby and Asenath Waite. Asenath's odd name emphasizes her sinister, otherworldly nature. Though this would be more of a modern reinterpretation; a Biblical name wouldn't seem out of place at all among the East Coast Establishment in the 1930s. If anything, their names would be a class marker hinting that Asenath and her father Ephraim belong to a really old, established family going all the way back to the Puritans.
- Ambiguous Ending: Upton, whose will is much stronger than Derby's, is mentioned in a much later story to have been given a clean bill of mental health and released from the asylum. What is not revealed is whether he has successfully managed to resist becoming the next body for Ephraim.
- Big Bad: Asenath. Until we find out "Asenath" has really been Ephraim the whole time.
- Body Horror: Derby's consciousness is permanently trapped in a rotting corpse. The real Asenath presumably suffered the same fate off-screen.
- Dissonant Serenity: The story starts off with Upton explaining, perfectly calmly and cordially, explaining how he put a bullet in his best friend's skull.
- Enemy to All Living Things: Asenath Waite. Specifically, dogs dislike her and act fearfully if they have to be near her.
- Expy: There are enough similarities between the Waite family and the Marsh family from The Shadow Over Innsmouth to argue that this story may have originally been intended as a prequel.
- Female Misogynist: Asenath seems to be one; she expresses anger over being born a woman since she believes that the male brain has "certain unique and far-reaching cosmic powers". But as it turns out, she's not really a woman, but a man in a woman's body.
- Foregone Conclusion: Derby dies.
- Grand Theft Me: Ephraim achieves this by switching bodies with Asenath and then with Derby.
- Half-Human Hybrid: Asenath is one of the Innsmouth fish-people, as evidenced by her bulgy eyes. Fortunately, or unfortunately, depending on how you look at it, she never gets the chance to undergo the Change: she's murdered twice-over while still young.
- Heterosexual Life-Partners: Derby and Upton.
- Hoist by His Own Petard: Derby himself admitted both verbally and in his last letter he got involved in horrific black magic rituals, which were the Devil's business and too disgusting to describe. It took him 3 years to realize this led to A Fate Worse Than Death.
- How We Got Here: The whole story is Upton explaining why he shot his friend.
- Immortality Immorality: The only way to become immortal is to swap bodies with someone.
- Kill It with Fire: Derby suggests cremating his Ephraim-possessed corpse, since shooting Ephraim didn't do any good.
- Mad Artist: Derby achieved some renown as a great poet writing nightmarish verse, years before the events in the story unfolded.
- Masculine Girl, Feminine Boy: Asenath and Edward, with the former the stronger and more assertive personality who dominates their marriage.
- Momma's Boy: Derby's quite dependent on his parents, which makes him easy prey for Asenath.
- Offing the Offspring: Ephraim killing Asenath in some manner. His thoughts on her, as read by Derby, are always spiteful — for not being a man and fully human, as he desired.
- Our Liches Are Different: Derby refers to Ephraim as a lich.
- Split Personality: Derby seems to exhibit this after marrying Asenath. It turns out be because Ephraim is swapping bodies with him.