Elly’s girlfriend lives inside her head. That doesn’t mean she isn’t real.
Susannah is a cerebral parasite, left behind by a failed alien invasion fleet. The two of them are stuck together forever. And they’re not the only ones.
This 2400+ short story was first published by Crossed Genres in their #12 issue of 2009.
Seriously, if the words "a romance between a girl and her alien parasitic brain slug" don't make you want to read this story, there is nothing more I can do for you.