A 14-year-old with a brilliant mind who lives on Oak Haven Island near Katie, using her resourcefulness and intellect to aid their survival. She quickly forms a strong bond with Katie, providing crucial information about their common adversary.

A wild red fox residing on Jacob's Ladder that shares an uncanny connection with Katie, serving as a harbinger of danger and a catalyst for her emotional healing.

The enigmatic and menacing creature from outer space that escapes confinement to wreak havoc, absorbing DNA from creatures it contacts and posing a significant threat to the protagonists.

Raleigh and Francesca are scientists detached from their daughter Libby, deeply involved in research on the Moloch creature but emotionally neglectful, contributing to Libby's loneliness.

Antagonistic young gang members responsible for a violent crime that devastated Katie's family, representing human depravity and chaos in the protagonist's past.

A corrupt government official whose machinations threaten Katie and Libby, characterized by his controlling and sinister nature, eventually becoming connected to the Moloch threat.

Robert Zenon's grandmother, marked by her intelligence and manipulation, who contrasts with Katie through her callousness and association with power and deception.