Well, if the fluff confirms it, the fluff confirms it. I can kvetch on the internet all I like and it won't change nothin'.
In reality, hybrids only occur with very closely related species - humans and chimps are a no-go - and are riddled with health issues.
While a hybrid could be an interesting character (perhaps playing off their inherited weaknesses as well as strengths, their sense of not belonging and hiding what they are from damn near everyone they meet), I've seen a fair few in fanfic over the the years and they almost all seem to be just appealing to the author's love of elves and half-elves in generic fantasy.
While I suppose some nasty individuals on both sides might go for that thing, according to their own fluff (with eldar the reproductive system being progressive) it would need to occur on multiple occasions. And the mother would either be willing or unable to stop the monster-child coming to term. Amazingly, love would seem a more likely origin for such a creature.
Last edited by Eremite; 09-07-10 at 12:29 PM.