Ryland Grace is a brilliant middle school science teacher and molecular biologist who unexpectedly becomes humanity's last hope. Intelligent, curious, and endlessly resourceful, he solves impossible problems through creativity rather than brute force. Although he's sarcastic, awkward, and often terrified, his compassion and determination drive him to protect others—even when every instinct tells him to run. Beneath his humor lies an ordinary man forced into extraordinary circumstances.

Rocky is an engineer from the planet Erid who becomes Ryland Grace's closest friend during their mission through space. Highly intelligent, practical, and fearless, Rocky communicates through musical tones and approaches every problem with logic and determination. Though physically very different from humans, his unwavering loyalty, curiosity, and willingness to risk everything for his friends make him an unforgettable companion. His unique perspective often leads to ingenious solutions that neither species could have achieved alone.