Crestfallen Studios

Okay I know that this is probably way off, but her goes.
The only other survivor of the Landorin massacre was Lyrra, and she went through the rest of her life thinking of it as a story to surpress the memories. So Since Rhue survived maybe he is making up Serena just to supress the memories and give him something to do.

Uh... Okay. Good theories aren't usually two sentences long, at least not if they're worthy of a topic...

Not to mention how many times this theory has already been said...