I first read these stories years, years ago, in the late 80s. And twenty years later, I still love them and consider them some of Smith's best work.
So here's a little spoiler-ridden analysis...
"The Dark Eidolon" is a great example of utter excess, Zothique-style. Years ago, in the city of Ummaos, the beggar boy Narthos was pleading for alms when he was trampled under hooves of a horse ridden by Prince Zotulla, and left for dead. But Narthos didn't die; he skulked off, leaving the city, and devoted his life to studying the dark arts. Changing his name to Namirrha, he became famous as one of the world's great sorcerers. Meanwhile, Zotulla has murdered his father (tsk!) and ascended to the throne of Ummaos.
One day, after one of Ummaos' city-wide orgies of drink and debauchery, a new palace arrives in Ummaos, seemingly erected overnight. It's the new home of Namirrha, and soon animated skeletons are delivering formal invitations to Zotulla and his court to enjoy Namirrha's hospitality.
What follows then is sheer glorious apeshit excess, the sort one gets only from Smith and a select few other authors. Every aspect of the resulting feast and the revenge that's taken is gone over in morbid detail, and seemingly more than a bit tongue-in-cheek. Namirrha subjects his victims to all sorts of indignities, and often it's so over-the-top that the reader can't help but chuckle a bit.
Still, there's a tiny bit of a moral. Namirrha ends up being undone by his own hubris, as even the dark and evil god he worships decides that the vengeance has gone too far. Kind of an interesting thought there...that mankind can be even more evil and depraved than the very gods of evil and depravity.
"The Dark Eidolon"'s utter batshit craziness makes it a must-read for any student of the macabre. And the subtle ironies and commentaries are worthy of deeper analysis.
Interestingly, for all its excess, "The Dark Eidolon" is devoid of any hint of necrophilia...but that slack is taken up by the next tale, "Morthylla," which is all about necrophilia, in a way.
"Morthylla" is a great contrast to TDE and it's great to read them back-to-back, as it's a very subdued, almost delicate tale.
In the city of Umbri (dubbed "The City of the Delta" by Smith, making one wonder if it's meant to stand in for New Orleans) lives the poet Valzain, known both for his writings and his status as a top-class voluptuary. But he's grown jaded and tired of it all, and seeks solace in a cemetery outside the city...where he meets a woman with a profile he's seen on old coins, who introduces herself as "the lamia Morthylla." (In Smith, the term "lamia" appears to apply to a female vampire, she-demon, or succubus, or a mixture of all three.) He immediately is enamored of her and seeks her company regularly.
There's a quiet, almost tender quality to it. The romance between Morthylla and Valzain is almost sweet, even when it's between a jaded guy who's sampled everything and a vampire. Naturally, it ends up that she's not really a vampire, and not really Morthylla....she's the courtesan Beldith, also grown jaded and tired, and who sought some thrills in the cemetery that night, and played a little game with Valzain.
Now's here where it gets interesting. The reader is left with the strong impression that Valzain, despite all his experience, has not yet slept with "Morthylla," and all his assignations with her have been for conversation and hand-holding. And yet, when he discovers that she's really only a mortal woman, he immediately loses interest. She loves him, strongly and sincerely, yet he loves the illusion of Morthylla more. She muses on how love always involves deception (a common tenet of the Victorian Decadent movement; the people you love always seek to deceive you); Valzain can't handle the romance without the deception.
It's also fairly relevant for our times, that the jaded youth has to seek his thrills in the outre and macabre, and when a normal, healthy love presents itself (or at least as healthy as one can get in Zothique), he abandons it.
Necrophilia in Smith's stories is generally on a strict carnal level, but this time we have a true love affair going on. And it's interesting that the love can't exist without the necrophiliac element.
Ultimately, Beldith goes back to her life in the demimonde, and Valzain can't handle life without his illusions and commits suicide. But after death....well, I won't spoil that much, except to note that it's a repeat of another theme sometimes found in the Zothique stories, that true romantic passion and fulfillment can only be found in death.
Hunt 'em down, read 'em both, folks. These are remarkable stories that stand the test of time.