Once upon a time, there existed three things. There were X-Men comics, those purveyors of exciting, soap operatic angst. There was the Comics Code Authority, which carefully kept that soap opera from getting too exciting. And there were pterodactyls, which need no introduction at all.
In those days the Comics Code, that legendarily draconian arbiter of good taste, decreed vampires, werewolves and other such ghouls verboten on the comics pages of the 50's and 60's, primly stating that children had no business reading anything so gruesome. While this mostly served to stamp out the EC horror comics line, it proved something of a stumbling block for superhero comics as well.
Still, there's always potential in vampire stories, even when you can't use vampires, so it came to pass that Roy Thomas and Neil Adams, then creators of X-Men, created themselves a bloodsucker that could pass muster under the suspicious eyes of the Comics Code. They dreamt up a lurching were-dactyl, a vampiric hypnotist that fed on mutant “life energy” and wore the ripped purple pants that must adorn all green, monstrous things. But the creature they had created, burdened with so many contradictory parts, inherited one thing they did not intend.
For Sauron, evil incarnate, has an inferiority complex.
Is it any surprise, with so mixed up a creature as this? He has no fangs for the intimate sucking of blood, no fiery passion that leads one to tear off a shirt and go howling through the woods. He absorbs energy from an awkward, hesitant distance. Even his origin story is cluttered; an ordinary human, scratched by a pterodactyl, who gained energy draining powers and later mutated into his present evil form. And he got the form wrong! His membranous wings are those of a bat, his tail long and yet curiously unimportant looking. He has only to walk into a museum to see that not only is he neither proper vampire nor true werewolf, he’s a pretty miserable excuse for a pterosaur too.
The sad thing is that Sauron clearly wants to be taken seriously. Works at it desperately, in fact--he went so far as to name himself after Tolkein's Sauron, which is a perfect a case of reach exceeding grasp as you're ever likely to see. You can imagine him roosting in a tree, watching the X-Men at play, thinking furiously of the most perfect monologue, the most vile threat, and as a result when he finally does come screeching out of the air he’s simply trying to hard. If nothing else, he's desperate to make sure everybody remembers who he is.
The X-Men persist, in a profusion of titles, their soap opera a little more risque and even more self obsessed. The Comics Code is gone, its grip on the industry waning in the early 80's. Now if Marvel wants vampires, they can have them. Dracula has a base on the moon. Blade lurks in grimy alleyways, stabbing monsters in the face. Even Spider Man has a vampire supporting character of his very own.
With this undead proliferation Sauron has been banished to the Savage Land, the Marvel dumping pit for jungle pulp characters and concepts. But even there, he pops up occasionally to scream at whichever hero happens to be passing by. This relic of a different time, this shambling anachronism, this histrionic, self pitying creature, refuses to be forgotten.