Since the time of the first tales of fantasy, the fae creatures that elves are representitive of have been the outlet of humans dreams and hopes. They are what we strive to look like, how long we want to live, how wise we wish we could be. Elves are a metaphor for the goals of human hope.
There have been a great many takes on elves, Tolkien's proud immortals, D&D's short, long-lived folk, Tad William's alien and reclusive sidhe, even Shadowrun's futuristic towers of arrogance. Many fae have been called elves, and many elves have been simply called fae, the distinction among them limited to the individuals point of view.
I was recently inspired by watching "The Two Towers" to offer a detailed look at a different sort of elf, the same as many, but different in some deep and meaninful ways. I hope this rendition can answer some of the age old questions about these immortal creatures.
Once a person begins to get the feel for fantasy, they begin to analyze it and invariably come to the same question as some point. "If elves are immortal, why aren't they in charge?"
It seems logical that a race that has forever to aquire and pass on knowledge would simply breed the other races into submission and simply outwait thier enimies. If age will never claim you, militarily you should become the master of stalemate, holding them in check untill time destroys them in a way you are immune from.
One possible answer would be to look at the breeding of elves. If children are rare, then having the numbers to overwhelm an opponent would be hard to come by. The other races can simple spawn like rabbits and win through force of numbers. But simply saying they don't reproduce that much strikes me a weak cop out.
Instead of simply not having children as often, what if the elves couldn't have children without a mate? That seems obvious, but rather than taking the casual view of mating we lesser creature hold, what if the elves also embodied out dreams of perfect mating? In a perfect joining of two people, each person is everything the other would ever need, now and forever. Forever for an immortal is a long time indeed. Being able to only join with one person for all eternity, one person and one person only, takes on a bit more consideration when that eternity will come to pass in your lifetime.
Consider that magic is, by definition, outside of nature. Elves, being immortal, are then outside of nature since they cannot die like other creatures, or landforms for that matter, mountains will crumble before an elf dies of old age. As elves are outside of nature, that makes them magical beings. Then may not be able to do all the nifty tricks, like become invisible at will or live inside a sapling, but they have a magical nature all the same.
Their magical nature will likely affect their lives and interactions with one another and other creatures. To reproduce, the would have to join with another person on a deeper level than other species. Some animals take mates for life, but few so called higher creatures choose to. The magical nature of elves may make reproduction impossible unless the involved persons are joined for life.
Such joinings are not something taken lightly and so children are scarce in the coming. Even once joined, an immortal's reproductive cyle is likely to be rather slow. With out the need to replace elders lost to age, the immortals body may not become fertile untill there is need.
A side effect of these complications to reproduction would be the fact that rape, while still traumatic, would never have unwanted offspring. To an immortal, abortions would be as alien and unthinkable to them as it would be unthinkable for humans to eat their young. Sexuality for recreation may be a casual affair, but with out any joining, it cannot produce anything other than stress relief with an occasional flurry of drama.
The elven race would almost be gaurenteed to be pure, as only a rare, and likely mentally imbalanced, immortal would choose to join with one outside the elven race. No matter how long lived that other race may be, the elf would watch their mate wither and die, and any chldren from the union would also wither, as would grand children and so on and so on. The loss of a mate would be very traumatic for an elf and often lead to madness and death.
While elves are immortal, they are not invurerable. They may be struck down like any other creature. One that has been bound in a union with the deceased elf would now only be half a creature. Widows and widowers could not re-marry, as it were, the bond is not "death do us part" but forever. Divorce isn't possible, the magic that gives them their immortal lives is no longer seperated, but joined, compeletly, absolutly, and permanatly. The spirit of the departed may well remain in the union, a ghost for a lover, gone but not yet left.
This point of view for elves may help to answer questions about their influence on the world and even possibilities for any half elves. After I spend some time thinking on it, I will attempt to answer the second most asked question "If I'm hundreds of years old, why am I first level?"