Extrovert Cee is literally alone on an island, where everything real is monochromatic and she wants to get back to her sister. Introvert Kasey is on a metaphorical island where she's surrounded by people but lives in fear of interacting with others. Any cli-fi part of the novel doesn't really start impacting the story in the preview, but it opens with the interesting juxtaposition of sisters in situations that make them uncomfortable when they both think anything is survivable as long as they have each other.