Please see attached Rough Sketch, made by a friend of mine (it's a good place to start): Chris (l) and Cat (r) are the romantic interests. Chris is Japanese, around 20 years old. Cat is half Japanese and Polish ("...her green, almond eyes sat well on her broad, Slavic face.") and also 20-ish. Her brownish hair is actually shorter than what's drawn, about shoulder length; importantly, her hair has a streak of white from around her left temple on down.
Behind them is Chris' sister, Maya, vampire-demon cyborg, late teens, also Japanese. I like the idea of just having her as a silhouette, with her red eyes and white, pointy teeth, but I'm quite open to other ideas.
I would like the cover to be (not sure about the term) photo-realistic people, not drawings (see my "Echoes of Family Lost" cover, attached).
Chris and Cat, for most of the book, are very much in love with each other, so their gaze towards one another should reflect that. Maya, their impending nemesis, while a killer, is also a mildly sympathetic figure in that she was tortured in the process of being created.
Please ask if you need to know more!
[UPDATE: getting some good designs in, so I wanted to add some clarification. While I use the term 'cyborg,' the only machine components of Chris and Maya is their SymCom artificial brains. They both have had improvements made to the neuromusculature of their bodies, evidenced by the scar that runs from shoulders to wrists, hips to ankles, and 4-6 scars across the chest. As it is my fault for not providing this level of detail in my initial brief, I shall not count another's interpretation of my poor description against your submission. Once I have chosen a winner, we can clean things up then. Thank you all so much for your great work!]