It was hinted last episode (or maybe the one before that) that the Sisters of Sylandri might be in cahoots with the Tachonises. Otherwise, how could they have gotten their hands on the Stone of Night Song.
Now, simply saying that they just want Sylandri back is one thing, I mean that could be all she wrote. But now, knowing that the elves are unable to reproduce, create new life of their own, makes the motivation to resurrect her might be their only way to continue propagate their people.
Brennan is so, soooooooooo fucking sneaky, man. I think he said somewhere in episode one that elves are very rare and seeing one in public is quite a spectacle. Most of us assumed that was just maybe because they kept to themselves. Nope, their entire bloodline is about to disappear and maybe some of them are getting quite desperate in finding ways to continue it.
