I was just reading the Wikipedia article "Elf" - specifically the section on Norse elves - and I just realized why Beowulf groups elves among the descendants of Cain. You see, Norse elves - the álfar - were some sort of deities or at least supernatural and much revered by the Norse. English elves presumably came from the same source, namely the old germanic religion of which the Norse one is the most common variant. The English, or rather Anglo-Saxon version was different, but the overlap was significant.
Now the author of Beowulf would have been a Christian (hence the references to Cain and Abel) and as such, the old gods and supernatural beings would either be absorbed as saints or rejected as evil. Clearly elves fell into the latter category, although we have since adopted a rather more charitable view.
Tolkien's elves (which are the basis for most fantasy elves today) rather strongly resemble the álfar, which doesn't surprise me in the least, given his extensive knowledge of germanic languages and the clear resemblance of the Rohirrim to Vikings. I wonder what that makes the people of Gondor - there are clear parallels between Númenor/Atalantë/whatever else he called it and Atlantis, but that doesn't help me. I recall them being descended from one of the three High Houses (or something) where the Rohirrim were descended from another (I can't remember what became of the third) but that doesn't help me, except in that they must be germanic as well, because the houses were related.
In other news, I'm thinking about decorating my room in a pagan fashion. Big fricking picture of Yggdrasill, Ganesh statue, statues of some goddesses (Freya? Athena? Kali? Artemis?). But it's already decorated with tons of anime stuff, so I might just go for a few pictures.
satisfied