At first glance,“Obsidian,” the first book in Jennifer L. Armentrout’s New York Times bestselling “Lux” series, looks like a pretty typical romance novel. There’s a woman with her arms draped around ...

Human-alien hybrids fill science fiction stories, and the most famous of these is Mr. Spock from Star Trek — the logical science officer of the starship Enterprise. Seeing such real-life beings born ...