Way back here I posited that Baleful Sky elves should default to 4 HD.
The reasons are the same as they were - I wanted elves to be something more than funny-eared humans, and to be taken as a possible threat when encountered.
Lairs & Encounters, however, has given me a bit to think about.
Elven spellswords are extraordinary members of their species - and built as Fighting 2, HD 1, Elf 4.
Near as I can tell, the Elven Courtier is Fighting 1, HD 1, Thief 1, Elf 2, which is a decent start for a "common" elf.
Let's assume for the moment the common elf is the Courtier, and most elves you meet at HD 4 cast as a Mage of 2nd level - my monster entry would be amended to say that elves cast as mages of half their HD.
From what we learn from Lairs and Encounters, it then follows that adolescent elves are HD3, casting as a 2nd level mage, and child elves are HD 2 - casting as a first level mage.
Circle back, then, to the image of elves as tricksters, small, furtive, ignorant of consequences and mortality - fey.
Is that image not childlike?
I've got two daughters - they've gone through a lot of dolls. Would a young elf think twice about grabbing that cute, chubby, burbling human infant?
Some group of young elves slipping through the woods just as human teens do comes across a party of regular humans - what happens if it goes badly? This group of essentially veterans with magic, against normal men?
Their parents are 4HD creatures. They're better than humans - and these are teenagers, so they think they're better than everybody. They've been "teenagers" for probably 20 years now.
Maybe that's how elves get the reputations they do. The adults are aloof, haughty, elite, sure - but they're older, wiser, circumspect.
In a species that reproduces sexually, attributes considered to be adult are a bit twisted by puberty and adolescence - and I bet a lot of these teenage elves wouldn't think twice about bullying a group of normal men to the point of violence. And one of them brought along their little sister or brother, and that one snuck over to the village and grabbed a baby to play with.
If any of that goes incredibly wrong - if the little sister is discovered in the village and slain, if the cocksure teenage elf is maimed - what happens then?
I'd bet that village ceases to exist, and elves start getting a reputation.
Fast forward a few hundred years and that forest is haunted, and we don't go there for wood - and there's not a human settlement within miles of the forest edge - none that aren't ruins.
“Elves are wonderful. They provoke wonder.
Elves are marvelous. They cause marvels.
Elves are fantastic. They create fantasies.
Elves are glamorous. They project glamour.
Elves are enchanting. They weave enchantment.
Elves are terrific. They beget terror.
The thing about words is that meanings can twist just like a snake, and if you want to find snakes look for them behind words that have changed their meaning.
No one ever said elves are nice. Elves are bad.”