freyar said:
... I'm not sure I see the overarching idea that pulls it all together (unlike, say, abberations or dragons).
Aberrations have an overarching idea?
Anyways...TSR and WotC have never really, IMO, done right by fey. You're right, they don't have an overarching theme, and they should.
Fey in D&D generally fall into one of two categories: nature spirits or emotional spirits. I've toyed with a planar setup that places celestial planes above, fiendish planes below, elemental planes "outside", and "conceptual/emotional" planes "within" the Prime Material. Elementals come from outside, Fey come from inside.
In traditional British folklore, fairies are usually categorized as trouping fairies or solitary fairies, and then again as members of the Seely and Unseely Courts. Brownies, buckawn, redcaps, and spriggan are solitary fairies, while sidhe and more closely human fairies are generally trouping fairies.
The eladrin are, frankly, TSR's best fey - except that they aren't.
I think what's too often missing is the sense of fey being unhuman. They're played for laughs, but fairies in folklore weren't laughing matters. They might look human, they might act human, but it is all sham and mockery - and even the kindest fey doesn't understand real emotion.
I enjoy fey, but use them sparingly in my game. They tend to be creepy "guides", in a metagame sense, directing the PCs and providing roleplaying encounters (that can occasionally degenerate into violence). Most recently, the PCs encountered a number of nixies - unnaturally pale, ("fish-belly white", to be exact) with bloodless lips and shark-like teeth, that hoarsely and repeatedly warned the characters "There's blood in the water" (a clue to a slaughter upstream - where the nixies had been severely corrupted by the exposure to blood and violence.)
(I like nixies. Few things seem to creep out characters and players like a boat surrounded by 5 or 6 nixies whispering "I love you. Don't you love me? Why don't you love me?" in little-girl voices as they try to charm the PCs and drag them under the water. I think it works because the nixies are so -close- to being human, unlike some tentacled aberration, and they are sincere. Severely twisted from the human perspective, but sincere.)