On one of the lists I subscribe to, someone recently brought up the question of what, if anything, makes paranormal heroes different from the heroes of non-paranormal romances. From the follow-up discussion, it seemed the poster was thinking mainly of supernatural creatures, although an alien with super powers or an extended lifespan would fit in, too. One suggested difference was that a person with superhuman powers, immortality, or very high intelligence would feel apart from ordinary mortals and might consider himself superior to them, having little in common with and no moral duty toward them. The naturally evolved vampire, Dr. Weyland, in Suzy McKee Charnas' THE VAMPIRE TAPESTRY frequently states that he regards human beings as "livestock" or "cattle," creatures to whom he has no obligations. At first glance, his position has a certain plausibility. Since he occupies the top of the food chain, as far above us as we are above apes or other higher orders of nonhuman animals, why shouldn't he have the right to use us in any way he chooses?
However, some people don't believe we have the right to treat nonhuman animals with any less consideration than human beings. Notorious utilitarian bioethicist Peter Singer, for example, summarizes that philosophy in this quote from his FAQ page:
"I argued in the opening chapter of Animal Liberation that humans and animals are equal in the sense that the fact that a being is human does not mean that we should give the interests of that being preference over the similar interests of other beings. That would be speciesism, and wrong for the same reasons that racism and sexism are wrong. Pain is equally bad, if it is felt by a human being or a mouse. We should treat beings as individuals, rather than as members of a species."
You can read the whole FAQ at: www.princeton.edu/~psinger/faq.html
Also, Wikipedia has a comprehensive entry on Singer's works and philosophy. I've read one of his books, and whatever one may think about his ethics, he has the clear-headedness to carry his theories to their logical conclusion. On the premise that what matters in the treatment of a creature is not the species, but the capacity of the individual, he says that all sentient animals have the right to be spared pain, but other rights depend on whether they have the mental ability to be aware of themselves as conscious beings or to plan, hope, and anticipate. To Singer, a healthy dog has more rights than a human fetus, a newborn infant, or a severely mentally disabled human being of any age. To the hard-line abortion opponents who equate the killing of a fetus with the killing of a newborn, Singer heartily agrees—and says it's sometimes okay to kill a newborn. In his view, a newborn infant or a brain-dead human being isn't a person. Moreover, he supports a movement to confer legal personhood on apes.
Suppose we encounter aliens who stand as far above us in the evolutionary scale as we do above chimpanzees or dogs. What if these aliens conquer Earth and decree that they have the right to enslave or eat us (as long as they don't cause unnecessary pain), because compared to them we're only animals?
In my opinion, sapience and self-awareness make a difference. No matter how superior to us these hypothetical aliens may be, that superiority doesn't give them a right to treat us as lower animals rather than persons. After all, most of us don't think of human beings with subnormal intelligence as non-persons. I don't approve of fictional vampires (whether supernatural or naturally evolved) who, on the grounds of their long lives and superhuman strength, speed, etc., claim the right to treat ordinary mortals as prey. I don't think the same attitude would be acceptable from aliens, either. This position does bring up the question of chimps, gorillas, and dolphins. Suppose they are proved to have self-awareness in some sense comparable to ours? Would that discovery entitle them to personhood? Maybe—but equality of rights? That's a knottier problem.
It's often assumed that what separates us from the great apes by an unbridgeable gulf is our capacity for abstract thinking and the type of language that goes with it (as opposed to the simple, concrete type of communication some chimps and gorillas have supposedly learned). What if the extraterrestrials possessed some mental power that has no analogue in Homo sapiens? Would they dismiss us from consideration as “persons” because we lack that power, whether it be telepathy or something presently unimaginable to us?
And what about sex? Would a superior alien race view sex with human partners, members of an “inferior” species, as a form of bestiality? (On this topic, by the way, Singer maintains the theoretical acceptability of sex with animals, as long as no harm or cruelty is involved.) An interesting point to ponder while writing inter-species romance.