I have images of a coldly fey water nymph, in a futuristic metropolis. She's mute, as they always are *g* but of course she can communicate through writing, text messages, maybe sign language. There should be intimations of her strange heritage. Leaky taps, puddles of water. Like the sea is trying to call her back? Maybe our hero has nightmares of her coming for him, all dead-eyed and icy-cold, where she drowns him in his bed? Which helps to account for his uneasiness with her.

Heeeee, I actually rewrote a HCA tale about a man's shadow taking over his life but set it in the Avatar the Last Airbender world. I never posted it anywhere tho as it is pretty much just an adaptation of the original and not derivative enough, imo, to put my name on it.

That sounds cool - maybe you should derivative it up. :)