Green as a representation of evil

[Lhunardawen]

But Ithryn Luin in themselves are ambivalent - for one thing, there is notion of them 'failing', but there is no sure knowledge, and mysterious cults set up by those are curious thing - perchance those were supposed to form opposition to Sauron in the East?

Unfortunately nobody knows (maybe Tolkien himself does, or maybe not) what happened to them as they passed to the East, but as this might be a possibility, they might also have been ensnared by Sauron, used for his purposes and vanished from Middle-Earth history (and the books as well).