This was sparked by the vampire discussion in the HWFF theology section, so I came back over here. The idea was of a space parasite that caused people to turn into vampires. That got me thinking what other things usually found in fantasy could be translated to a science fiction story? A great many, I think. They can be done well, too.

Since the 4th birthday party is dragon theme, let's start there. I think dragons would be pretty easy to use in sci-fi. You could even leave in their more magical elements like telepathy, fire-breathing, and whatever else dragons might have. Same with gryphons, hippogriffs, Elves, fae/faerie/ and so on.

What do you think? How far can science-fiction take fantasy elements and reinvent them into a science fiction? Can it be taken further into fantasy tropes and aesthetics? Or does it reach a point where it no longer works?

The border between Science Fiction and Fantasy is rather fluid, and was once even more so---many stories that we would now consider firmly Fantasy were once sold as Science Fiction. Pern. The "Witch World" series. The Incomplete Enchanter (etc.). Three Hearts and Three Lions. And so on.

Part of why the trend has been toward a firmer boundary between the two is, I think, because Fantasy has become a bigger and more accepted genre in its own right; large numbers of people will buy something that's labeled as Fantasy. But part of it is also that in the 50s and surrounding decades, some scientists, and more importantly highly influential science fiction authors and editors (in particular John Campbell, editor of Analog, the most prestigious and high-paying science fiction magazine), were firmly convinced that what was then called "psi"---telepathy, telekinetics, etc.---was a real phenomenon and so an eminently suitable subject for even the hardest of Hard Science Fiction.

The main difference between a fantasy and a science fiction version of such elements is how they're treated. With dragons, for example, fantasy doesn't (usually) care how they fly and breathe fire, and to defeat one the hero will usually stick a sword in a weak spot in its armor. A science fiction treatment, on the other hand, will glance at least cursorily at the physics of flight (making them hollow-boned like birds, for example), and a hero might defeat a dragon by throwing a bucket of water down its throat (as the protagonist of Three Hearts and Three Lions does).

The truth of the matter is that you can combine any elements in any way you want. The trick is figuring out what genre to market it under afterwards.

As is the case with all genres--and Jon touched on this--sci-fi is defined not such much by a set of rules as it is by an overall feel. To accurately market something as sci-fi the final, complete book must fit within the essence of the genre. Therefore, if you put dragons in your sci-fi, the final product must still feel like a sci-fi novel, or you'll have to market it as something else, perhaps a hybrid genre.

One way to do that would be to look into the science of the "magic," as Jon mentioned. Like having a virus cause vampires. That is a "scientific" explanation--a way of viewing the paranormal element from a sci-fi mindset.

On the flipside, space opera is often gleefully unexplained in terms of science and may be loaded with fantastical creatures, but it still "feels" sci-fi because it is loaded with tech. Star Wars being the classic example, of course. On the same note, alien societies provide a lot of opportunity to bring in the paranormal to a sci-fi setting.

Precisely!! Sci-fi stories are (in my mind anyway-a side effect of too much Star Trek and Doctor Who...) synonymous with countless alien races. What humans call 'vampires' could just be a stately, advanced, lithe, fanged race that doesn't even drink blood and werewolves would just be a race of shapeshifters that are locked in on a lupine form.

Sorry. I have limited imagination for inventing new races and a deep love for legends...so I combined them.

As I alluded to above, whether things like Star Trek, Star Wars, etc., are really "science fiction" as opposed to some other genre with a superficially science-fiction-y setting is a matter of much debate. (The very name "space opera" may be derived from the term "horse opera," which described Westerns as the same old stories, just in the setting of the Wild West.)

Vampires are certainly something that science fiction can explain ... but "stately," "advanced," and "lithe" aren't the core features I would identify, "drinking blood" is, and it's the one thing that we could most easily find a scientific explanation for. A race might lack the ability to turn iron from vegetable matter into hemoglobin, for example.

I've done something similar. In one of my WIPs, future genetic engineers "invent" werewolves, creating "the bi-nucleic man"---people with both the human and the lupine genome in their cells, with an additional set of genetic and epigenetic information to keep the two separate, enable the transition of dominance between the two, and ensure that the person keeps his or her human mind throughout.

I've thought about this a lot especially since there is no magic in my fantasy world. So I can't pull out the "Oh, its done by magic card."
I have Dragons and Werewolves.
The dragons aren't so hard especially since their is only two that breathe fire and one of them is flightless.
Only two of my dragon breeds have wings so the rest are all pretty much dinosaurs. One of the flying one's is about a foot long with wings much larger than its body. The other is more like 15 foot long posing a much bigger problem for flight. I haven't got into the details of these dragons yet but I'm most likely to ignore the problem mostly like most writer's have.

My Werewolves are slightly more problematic. The current model i'm working with has the Werewolves look in appearance halfway between man and wolf. Also with a large surge of adrenaline their muscles contract and their hair stands on end and gives them a much more wolf-like appearance.