Of all the genres I've worked with, Sci-Fi is one that's really close to my heart. Perhaps it's because I was reared on Sci-Fi, or because my family is the kind to pause a show or movie in the middle of a scene to discuss what ideas are being expressed there underneath the plotline of the story, and what it all means. Drives my brother crazy.
When you think about Sci-Fi, what really comes to mind, hmm? Aliens? That's a faction. There's also genetic engineering. There's also robots. There's also space travel without aliens. There's time travel. There's also "after the end" stories that look at humanity's existence after the earth is gone. There's aliens that serve as mind-bending weirdness, biological viabilities, basically human creatures, and eerily familiar foils of the human condition.
At the end of the day, and from the very beginning, that's what Sci-Fi is about. No matter how human the characters may be or not, it's about