I'm searching for a fanfic that I've seen on ff.net in the past. I don't remember the name, but it's definitely AU.
In the fic, vampires are actually a different species from another planet. Bella works for the government and captures Edward after he kills Jacob. She has also constructed a space travel vehicle, which Edward uses to kidnap Bella and take her back to the Volturi, who originally sent Edward to Earth for her. Edward continuously threatens to kill Bella for holding him captive, but (obviously) they fall for each other. It tends to be dark at times, and it's definitely rated M.
I like this author's portrayal of Edward: DarkEdward=SexyEdward.
Thanks in advance to anyone who can help!