I'm a way back sci fi fan, but until I started planning "Relocated" last fall, I'd never written any, so partly to get myself past my "sci fi" block, I decided to write a sci fi novel for 2010 NANO.
In my YA sci fi, "Relocated," the main character, 14 year old Raketh (Keth) Frey is an Aleyni/human mix. Aleynis are dark skinned, gray eyed, aliens with psi abilities. In the Terran Federation, use of psi is illegal, and relations between the Aleyni and the Terran Federation are strained at best.
Why dark skin? Well, I wanted my aliens to look distinctive, and I liked the idea of casting against type and making the dark skinned guys the good guys. Plus that's just how they looked in my head.