The Inner Self
The writing style of The Fallen Star definitely describes external action—it'd be hard not to when Death Walkers are on Gemma's trail—but it focuses a lot on Gemma's inner thoughts as well. As soon as anything happens, we get Gemma's emotional response and her questions about it. For example, when Gemma is first transported to Laylen's house, we get a rundown of the events, but we also get Gemma's inner thoughts about whether or not she's going crazy:
What was happening to me? Was I heading towards an emotional breakdown? Was I going to end up locked away in a padded cell somewhere, screaming at the top of my lungs that everything I said was true—that I wasn't crazy? (12.2)
The writing style spends a lot of time on Gemma's inner thoughts and her emotions—which makes perfect sense, since her emotions are so central to the story. They're brand spanking new, after all, plus they might bring about the end of the world. So yeah, feelings are front and center in this narrative.