I think truly compelling fiction is incredibly realistic, whether it's set on a spaceship or in your own backyard. A book that makes the reader gasp for breath because they've just been emotionally gut-punched is real, and it doesn't matter that we're talking about things that never happened to people that don't exist.
It's those gut punches that I go for in every book I write. Whether I'm letting the reader in on some horrific practices in early insane asylums, showing a nine-year-old child defending her water source in order to survive in a parched world, or giving vent to the very real and often ignored world of female rage, I try to bring real life into every page.
I think this is true of my fantasy, GIVEN TO THE SEA, as well. Yes, the setting is foreign, but the people are like us - people. They are in extraordinary situations - whether asked to give their own life for the continuation of others', take their assumed place in the family tree, whittle the weak from their population in order to give strength to the whole, or fated to carry the last blood of a dying race - these are people that face struggles most of us can relate to in our own way. And if none of that strikes a chord, there's always the tried-and-true unrequited love that we all know (probably a little too well).
If you know anything about my writing, you probably know that SEA will make you cry at some point, cringe at others, and hopefully laugh once or twice.
Most importantly, it's going to feel real.