This was really wonderful! I've read a lot of 'End of the World' type stories, but this one was so detailed and so attentive to the little things. But I was wondering: Why did you leave out Aragorn and Arwen's son? I can't remember his name (begins with an E, I know that much), but he was definitely there. It worked well, but it would have been nice to see him at least mentioned.
And this whole time I thought the Non-Tenth WAS going to be Bill. Wonderful bit of OFUM-ness :P
The end of this chapter is so cute! I can just imagine the way Glorfindel's being a bit of a limp rag as Karyn's trying to get him into her bed. But he's got to be enjoying every second of it. :D Also, I really like how you're having their relationship progress at a more natural rate, instead of 'Hi. Wanna fuck?' like you tend to see with a lot of fics containing original characters.